Meteorite Times Magazine

ContentsPaul Harris

Featured Articles

Accretion Desk by Martin HorejsiJim’s Fragments by Jim TobinMeteorite Market Trends by Michael BloodBob’s Findings by Robert VerishMicro Visions by John KashubaNorm’s Tektite Teasers by Norm LehrmanMr. Monning’s Collection by Anne BlackIMCA Insights by The IMCA TeamMeteorite of the Month by EditorTektite of the Month by Editor

Terms Of Use

Materials contained in and linked to f rom this website do not necessarily ref lect the views oropinions of The Meteorite Exchange, Inc., nor those of any person connected therewith. In noevent shall The Meteorite Exchange, Inc. be responsible for, nor liable for, exposure to any suchmaterial in any form by any person or persons, whether written, graphic, audio or otherwise,presented on this or by any other website, web page or other cyber location linked to f rom thiswebsite. The Meteorite Exchange, Inc. does not endorse, edit nor hold any copyright interest inany material found on any website, web page or other cyber location linked to f rom this website.

The Meteorite Exchange, Inc. shall not be held liable for any misinformation by any author, dealerand or seller. In no event will The Meteorite Exchange, Inc. be liable for any damages, includingany loss of prof its, lost savings, or any other commercial damage, including but not limited tospecial, consequential, or other damages arising out of this service.

© Copyright 2002–2015 The Meteorite Exchange, Inc. All rights reserved.

No reproduction of copyrighted material is allowed by any means without prior written permissionof the copyright owner.

Meteorite Times Magazine

The Chiang Khan Meteorite Fall: A Gift That Just Keeps GivingMart in Horejsi

At 5:30 in the morning on November 17, 1981, a f ireball exploded high above the citizens Ban Klang andChiang-Khan in the province of Loei in Thailand. Loud thunderous reports rolled across the land rightbefore a shower of stones pelted the landscape.

My pleasantly oriented individual of Chiang-Kahn sits atop a one-cmcube facing away from the center of the earth.

Scientists arrived on scene several days af ter the locals had gathered up all the easy-to-f ind pieces thatamounted to about a third of a kilo in the form of 31 separate pieces with the largest at 51 gram.

A couple weeks later another piece was found but that one weighed more than twice that of all theprevious material amounted. So with the additional 800g individual, the total known weight of Chiang-Khanunof f icially broke the one kilogram mark. Oddly, the TKW of this H6 chondrite is usually reported as 367grams, or as the initial amount found shortly af ter the fall.

But the TKW story continues. In 2000, a fellow named Oliver Alge mounted a week-long expedition to thestrewnf ield. That week turned into several months. Oliver recounts his story online and in a paper thataccompanied many of the specimens that he sold as part of fund-raising ef fort. More on that ef fort isavailable on Oliver’s website.

Fund raising with meteorites is not a new thing but is relatively rare. I wrote about my experience with whatI called “Bakesale Juanchings” or small individauls f rom that famous fall that were collected by studentsand teachers, then brought to America to be sold at the Tucson show. I was lucky to play a small part inthat event buy buying their stones, and then selling them to recover my cost since my money was alreadyheaded back to the schools in China. Here’s some info on that f rom a previous Meteorite Times article.

This is a excerpt of Oliver’s Chiang-Kahn story as described on his website.

“Due to the political circumstances prevailing in Laos at that time, there are hardly any testimonies aboutthis meteorite fall from there. My Chiang-Khan expedition 2000 was initially intended to last one weekonly, but actually I spent the whole time from November till the end of February 2001 (and again 6

month) in the strewnfield and was able to shed some light into this darkness.

I met a Laotian army officer who, right after the fall, was entrusted by the government with the task ofseizing all fallen stones from the locals (threatening people with punishment!), in order to hand thesespecimens over to the authorities in Vientiane. People were told that this was dangerous Thai material.Subsequently, the specimens are said to have been sold to the Soviets.’

A oriented meteorite shows the earth only one side during it’s fall. Thecrust of this Chiang-Khan individual is mostly intact and contractioncracks are visible.

“About half of the persons I interrogated declared a fall direction opposed to the one officially published:according to them, the fireball traveled southwards, to Thailand, coming from the North (Laos). With Thaiobservers, this variant of the reports is easy to explain: The tense political situation of those daysinduced the population to conclude that Laos had fired missiles against Thai territory during the night.Due to the time of the fall, hardly anybody will have witnessed the event visually; the enormousexplosion jerked people from their sleep and then engendered this story as their first thought.

I personally convinced myself at 5.30 AM in Ban Klang that except for a few dozen dogs sleeping in thestreets, no more than a handful of people could have experienced this natural spectacle.�Such fallreports by Laotians, on the other hand, can only be explained by yet another meteorite fall. Theaforesaid Laotian army officer saw the fireball coming from the North. He was on night watch in Bagmeewhen, at about 3 AM, he saw the fireball detonate at an angle of some 45 degrees to the observer.Almost all reports from Laos contain a different fall time and a North-South motion.”

Even as an H6, there are still small chondrules that poked their littlespherical head up during reentry. The tiny round bumps make viewingChiang-Khan under magnification much more interesting.

“A Thai fisherman gave a further fascinating account: at said time, he was on the Mekhong river, wherehe had cast his net to gather some fish for breakfast. He beheld the “devil’s ball” coming from South, andsoon it vanished with a mighty burst. He had to seek shelter against the falling stones under a woolblanket, and the pieces that, in quest of a new home, were laying siege to his boat filled both his hands.Afterwards, he said, he had thrown “the ugly black stones”, which for sure meant no good, into the river.”

For the serious meteorite enthusiast, the trailing edge of an orientedmeteorite can be as interesting as the leading edge, sometimes evenmore so. Still, the cone or bullet-shaped front end is what really makesa valuable orientated specimen. And Chiang-Kahn does not disappoint.

“Nobody was able anymore to give precise indications as to the exact date of the event. Some 20 yearsago it was, so they say, in the month of November, without doubt – that’s what I was told in the villagesof the strewnfield. Whatever it was that happened then – one is led to presume a second meteorite fallon the same day or on the day after. According to recent research (isotope analysis), the two largespecimens, which are in private Collection and in Chulalongkorn University, Bangkok, do not originatefrom the Chiang-Khan fall. They are believed to have been transported into Thailand from Laos. Twosmall pieces from Thailand were analyzed, one is H4 tending to H5; one was determined to be H5 inJapan, whereas the large pieces are H6. Most of all, the noble gas contents of the large specimens differextremely from those of the Chiang-Khan pieces!”

Thank you again Oliver for working in the f ield of Chiang Kahn in order to share the story with us, for this ishow meteorite history is made.

Until next time….

Meteorite Times Magazine

Summertime FuntimeJames Tobin

Well summer is nearly over as I write this. It has been a fun season this year. Got in a couple trip to thedesert for astrophotography. Got some ceramic pieces made and with both those interests tried newequipment and techniques. I try to never stop learning new things. This article has f rankly been a problem. Ihave been so busy building Canon camera coolers and electronic focuser attachments and other things formy star imaging that I have only been doing routine work with meteorites. Normal cleaning and cutting anddiamond lapping. I have not been cutting into anything knew to f ind exciting unseen treasures. But I amwaiting to hear back any time about three very cool stones that are out for classif ication. I admit to beinglike a little kid when it comes to waiting for laboratory work. I treat it like Christmas Day. I know there is abig reveal in the future when the results come back and it will either validate the personal guesses I havemadeabout the stones or surprise me in a wonderful way perhaps.

I found a few months ago a very f riable stone while cutting some mixed up boxes of NWA material. It had athick layer on the outside that was very crumbly bu,t it was full of wonderful chondrules some of whichwere quite large. I had to cut several slices to get into the heart of the stone and away f rom the outsidethat was falling apart. Here is one of the outer slices that was starting to get better. It is one of the stone Iam waiting to hear the results on.

I usually take a thin slice f rom the stones as I am making the samples to send of f for classif ication. Thethin slice goes to my lab in the garage and becomes a thin section which I examine while waiting on the realresults. I have never sent just anything of f for classif ication. It has always been the more special stones.But in the future I may begin sending of f some the more ordinary material if labs will accept it.

I have described the process of making the thin sections in the past. It is for me a hand made deal. I use apowered diamond lap for the f irst part but af ter the material is starting to get thin I go to all by handgrinding. It takes a while and there are a lot of stops to place the slide in my polarized light viewer. Buteventually I get to somewhere very close to 30 microns. I made a few thin sections this summer. They willf ind their way to the camera in the future to get imaged.

I just love all kinds of meteorites but have to admit I have a real sof t spot for chondrule rich type 3 and 4ordinary chondrites. I am just fascinated by the way they look as thin sections in polarized light under amicroscope. When I was young I got involved in commercial macro photography. I did work for a group oflocal commercial artists and advertising f irms shooting all their small products for print ads. I was strugglingas a young man on my own to make ends meet and the extra money was really welcome. It was greattraining and today I still love getting in super close on my meteorites and f inding out what is there tocapture photographically.

Seems like all my hobbies and interests f ind their way back to meteorites sooner or later. My ceramic art ismade with meteorite dust mixed into the clay. I am playing currently with some exciting new projects that Ihope will actually resemble meteorite slices when the mosaic tiles are done. My gold and silver jewelrywork has been including more pieces of meteorite as time goes on.

This is the third level of experimentation for my artistic vision of meteorites in clay. I have made thousandsof tiny artif icial chondrules with about ten dif ferent mixtures and colors. I am about ready to try a realmosaic.

So does all this mean that I am obsessed with meteorites and need to f ind a program. Well maybe. But asfar as I no there is no program like MA (meteorites anonymous). Maybe there should be.

If things go as currently planned I will get some meteorite hunting in later in the year. Has been a fewmonths since I did any of that. So far retirement has been anything but rest for me. I have been doing stuf feveryday that I had no time for while I was working and that for me is the best. I can spend a few days oneach thing I love, and mix meteorites into most of them and work on astro images at night.

There is a Gold Basin Anniversary celebration coming up and going is on my short list of things I want todo. I have been thinking it is pretty dark out there I could take along some stuf f and maybe catch someastrophotos at night out there. That is another mix I have not done for a while. Star images f rom astrewnf ield is sounding cooler every time I think about it. If I don’t f ind any meteorites during the day thereis always the chance I will get some good images at night.

I guess at some point I will have to reign in these hobbies and just pick a couple, but for right now I amenjoying being all over the place with them. They all stay f resh since I don’t do any of them all the time.

I know there was not a lot of substance in this article. Summer just does not seem like the time to be reallyserious and scholarly. So I apologize for the glimpse into my daily retirement life. Promise the next articlewill have depth and information.

But now it is time to go and empty the kiln. Bye

Meteorite Times Magazine

Bob’s Bulletin – Vol. 1 No. 3Robert Verish

A newsletter for “orphaned” meteorites from the USA.

In my f irst Bulletin, I introduced the phrase “orphaned-meteorites f rom the USA”. I def ined these “orphans”as being unwitnessed-fall Ordinary Chondrite (OC) meteorite “f inds” that are recovered in the U.S.

Unfortunately, the vast majority of U.S. f inds are of this type.I went on to write that these U.S. f inds were being orphaned f rom the family of “approved” meteorites forthe following reasons:

1) The lack of funding for U.S. researchers to authenticate, classify, and document/record these U.S. OCf inds has resulted in several new [negative]; trends.

2) The increasing trend of commercializing the classifying of meteorites by U.S. researchers has pricedU.S. OC f inds out of the market, and

3) The increasing trend of U.S. researchers to turn away OC f inds, even when f inders of U.S. OCmeteorites are willing to pay for their classif ication.

In my 2nd Bulletin, I went into more detail about why I use the phrase “orphaned-meteorites f rom theUSA”. I focused on the lack of U.S.-tax-dollar-funding and why no funding was going towards theclassif ication of these particular meteorites. In hindsight, I now realize that I should have pointed-out thatthere is also a lack of funding for just authenticating and recording that a U.S. meteorite has been found.This function should never be confused with “classifying” a meteorite, which is obviously way more laborintensive and costly.

My point is this: if you already have dedicated U.S. researchers (who have been approved for classifying

meteorites) and they are already having U.S. meteorite f inds being brought to them, and they are alreadydeciding (visually) whether the f ind is an OC (and consequently, whether they will agree to classify thef ind), then why not take one more additional step and record this f ind and have that data entered intosome sort of U.S. OC database? Is it because there are no funds allocated to do this function? Or worse,it actually is funded, but for some bureaucratic reason this function has been deemed “not important”?

[Yes, I know about “provisional” meteorites, but those are a separate issue. For starters, they are:1) ONLY numbers that2) STILL have to be formally assigned to pre-classif ied (and of ten unauthenticated) rocks that are3) ONLY f rom DCAs (Dense Collection Areas). But DCAs can4) ONLY be assigned af ter two or more meteorites have already been formally approved by the MetSoc(meteoritical Society) NomCom (Nomenclature Committee).But what I am suggesting is much less involved, and although it may have to be done outside of MetSoc,it still could be done by volunteers for U.S. OC f inds.]

A simple question that is of ten asked is, “How many of these ‘orphaned’ meteorites are there?” But, nowyou see why this question is so dif f icult to answer. We simply don’t know.

So, in order for me to do my part to bring attention to this ongoing and growing problem, I will continue togather data, and along with others, make a list of what we know to be “orphaned meteorites”.To that end, in this newsletter-format, I’m introducing the next f ive “orphaned” U.S. meteorite f inds:

Newsletter for Orphaned Meteorites from USA – Volume 1 No. 3 — September 2015

Meteorite-Recovery Information Petrographic Descriptions Meteorite Specimen PetrographicDescriptions:

N140531A N140531B N140531C N150814D N150814E

Example Petrographic Description

Field ID Number N140531A

Newsletter 01-3Location Nevada, USAThin-section ID Number VTBDDimensions 3.5cm x 2.5cm x 2cmWeight 30.05 gramsType Specimen 6.4gram endcut – plus thin-sectionClass Ordinary Chondrite (quite possibly an LL6)<ahref=”??”name=”Weathering Grade”>Weathering Grade mid-range (but very likely above “W3”)<ahref=”??”name=”Shock Stage”>Shock Stage low (most likely “S2” or lower)Macroscopic Description — R. VerishThis meteorite is a well-rounded, whole individual stone. The dark, grayish-brown exterior of thischondrite is covered 90% with a thick, relict fusion crust. Very little in the way of rust-spots. The interior isa dark-brown, compact matrix with very low metal-grain content, and few troilite grains. The chondrulesand inclusions are not distinct, but don’t appear to be variable in size.Thin Section Description — R. VerishThe section exhibits a variety of chondule sizes (some up to 3 mm), but most are ill-def ined in a dark-brown, iron oxide-rich matrix of f ine-grained silicates, troilite and rare metal. Although the exterior of thismeteorite has experienced only minimal physical weathering, the interior has undergone chemicalweathering and is highly weathered. Very weak mosaic shock ef fects are present. Silicates areequilibrated. This meteorite is probably a low-shock, equilibrated LL-chondrite.USA Orphaned Meteorite Images for Specimen ID# N140531A

The above example is one way in which I can bring attention to what I predict will be an increasing numberof unclassif ied meteorites found here in the USA. Hopefully, attention will be drawn to what I see as agrowing problem, and maybe some institution will of fer to help get some of these orphans classif ied andcataloged.

A newsletter for “orphaned” meteorites from the USA.

References:

Meteoritical Bulletin: the search results for all provisional meteorites found in “USA” – Published byMeteoritical Society – Meteoritical Bulletin, Database.

Meteorites of California the list of formally-recognized California meteorite falls and f inds.

My previous articles can be found *HERE*

For for more information, please contact me by email: Bolide*chaser

Meteorite Times Magazine

Micro Visions 3.00John Kashuba

3.00 is a rarely given petrologic grade assigned to meteorites which experienced the lowest levels ofthermal alteration on the parent body. (Aqueous alteration is another matter.) NWA 8276 L3.00 wasassigned this grade based on laboratory tests and a study by Grossman and Brearley published in 2005.

Among many f indings the study’s authors showed that at the onset of thermal metamorphism the averagechromium content of iron rich olivine grains in chondrules was relatively high. As metamorphism proceededthose levels receded. And, at the same time, the variance among the values making up those averageschanged – starting with a narrow variance, widening then narrowing again with advancing metamorphism.

Combining these two characteristics, Grossman and Brearley presented a scheme for classif ication of verylow petrologic grade chondrites. See this graphically on Grossman and Brearley (2005) page 113, Fig. 15.These characteristics and hence the method has the advantage of being resistant to the ef fects of parentbody aqueous alteration and terrestrial weathering.

The paper presents numerous other thermal metamorphism correlated phenomena including changes incore to rim Cr zoning in ferroan olivine grains, the development of distinct chromite inclusions, themigration of troilite and the expulsion of sulfur f rom f ine chondrite matrix.

Most of this is invisible to our optical microscope but we are still able to enjoy this near-pristine meteorite inthin section.

One centimeter square polished surface. Packed chondrules and dark matrix. Incident light. NWA 8276L3.00

Metal in and around a chondrule. Field of view is 3 mm wide. Incident light. NWA 8276 L3.00

A small metal-layered chondrule. Field of view is 3 mm wide. Incident light. NWA 8276 L3.00

Radial pyroxene chondrule with bleached rim indicative of parent body aqueous alteration. FOV = 3 mmwide. Incident light. NWA 8276 L3.00

Same RP chondrule in partially crossed-polarized light. FOV = 3 mm wide. NWA 8276 L3.00

Edge of the same altered RP chondrule in XPL. FOV = 0.3 mm wide. NWA 8276 L3.00

Overview in XPL showing that many chondrules are porphyritic olivine pyroxene chondrules. FOV = 8.6 mmwide. NWA 8276 L3.00

POP chondrule in XPL. FOV = 3 mm wide. NWA 8276 L3.00

POP chondrule in XPL. FOV = 3 mm wide. NWA 8276 L3.00

Polysomatic barred olivine chondrule in XPL. FOV = 3 mm wide. NWA 8276 L3.00

Barred olivine chondrule in XPL. FOV = 3 mm wide. NWA 8276 L3.00

Same barred olivine chondrule in plane-polarized light. No devitrif ication of the glass between bars isapparent. If the glass had started to crystallize we might have seen f ine needles extending f rom bars intothe glass between them. FOV = 0.3 mm wide. NWA 8276 L3.00

Same barred olivine chondrule in XPL. The space between the bars is dark attesting to its glassy state. Thesof tly def ined violet zones are places where the bars do not occupy the entire thickness of the thin sectionsample. The FOV = 0.3 mm wide. NWA 8276 L3.00

Norm’s Tektite Teasers: Pseudotektites , a Tektite Teaser indeed!

by Norm Lehrman (www.TektiteSource.com)

There is a family of remarkably similar (and usually controversial) natural glasses, including, Saffordites

(aka” Arizonaites”)Colombianites, Healdsburgites, and Philippine Amerikanites, which I term

“pseudotektites”. Placed side by side with the real thing, these look very much like tektites, but they

almost certainly are not. We are often approached by individuals that are convinced that they have

discovered new tektites or strewnfields. Mostly, the claims can be readily dismissed, but the best-

looking ones (pictured below), force us to critically review our tektite recognition criteria.

If those of us who know what tektites are should be asked to describe them to someone unfamiliar with

them, I suspect all would include things like dimpled skin, aerodynamic shapes, composed of glass, black

or green, not gray. There’s more, but these are prominent descriptors. However, the pseudotektites

discussed in this article pose some challenges:

Their skin ornamentation---dimpling, pitting, grooving is effectively indiscernible from that of

true tektites.

Their transmitted light color is often a smoky- lavender, not a color used in our definition.

Tektite-like morphologies are fairly common in the pseudotektites, particularly patties, biscuits,

spheroids, and occasionally, teardrops (pictured below).

Assuming that we are correct that these stones under discussion are truly not tektites (and I am quite

sure of that fact), then we must devaluate the diagnostic usefulness of the most visually obvious

features of a tektite: skin-ornamentation, aerodynamic morphology, and basic dark glass composition.

These are not peculiar to tektites.

In searching for characteristics not requiring a laboratory that truly are (or are not) fundamental to the

nature of a tektite, I have narrowed my observations to two key negative discriminants.

1) Gray transmitted light color and/or deflection of a delicately suspended magnet indicates the

presence of crystalline magnetite. Tektites are given birth in a monstrous plasma fireball. It is

true and is probably a direct consequence of formation, that tektite glass is of extremely high

purity, devoid of volatiles, and all constituent elements are fully dissolved in the glass. There are

never any primary crystallites at all.

2) Internal flow-bands or schlieren, when present, are invariably cut by the morphological surface

in pseudotektites. Tektites (when unbroken) are complete primary bodies. Any internal fabric

will conform with its bounding morphological surface. The teardrop-morphology Saffordite

pictured below is by this criterion recognized as not being a primary aerodynamic form, but is

rather an accidental erosional/corrosional similitude of a teardrop that is not complete, but is a

remnant of what was once a very much larger primary (volcanic) domain.

The “morphologically-truncated banding” is a valuable recognition tool. A splashform tektite is a

complete three-dimensional body, a flying blob of molten glass enclosed entirely within itself. Every

viscous taffy-like internal band will honor the ultimate external bounding surface of the shape.

Consider a volcanic flow-dome complex composed all or in part of obsidian. Flow-banded domains may

extend for meters or even tens of meters. Now, in your mind, let that body chaotically fracture in the

accumulated trauma of deep time and let advancing fronts of hydration, devitrification, and other forms

of erosion eat into these fracture faces until only a few “buttons” remain in the most central hearts of

the boulders. What would they look like? My answer? Saffordites, Healsdsburgites, Colombianites, and

(I think) Amerikanites.

(There is something of a scientific mystery hidden in the “Amerikanite” heading:. In my introductory

photo, you will take note of an “Amerikanite” from the Philippines. H. Otley Beyer, father of

Philippinites, routinely included in his specimen collecting inventories a heading entitled “Amerikanites”,

and it is clear from his usage that he was referring to pebbles of terrestrial obsidian that he recognized

as masquerading as Philippine tektites. Beyer, to my knowledge, never explains or defines an

“Amerikanite” in print. But I am willing to bet that it is a sibling of Safforfdites, Healdsburgites, and

Colombianites! The one example in our collection fits nicely on that shelf). These weirdities have a

story of their own!

So what are pseudotektites if they are not tektites?

I believe these to represent the final skeletal traces of either very old obsidian or glass that was

chemically unstable in its weathering environment.

All glass is geologically metastable and does hydrate, devitrify and recompose (a new word, I think, but

they do not strictly decompose, but rather transform from an amorphous state into a crystalline

substance, essentially the opposite of decompose, hence, “recompose”) into clays over a few tens of

millions of years. Logically, the last bits of remnant glass, geological moments from obliteration and

oblivion, must have a corroded and etched skeletal appearance. They truly are quite magical objects in

their own right.

These are the most ancient grandfathers of their species and when they are gone their ancestral rock

will be extinct. We humans have belatedly learned to care about the passing of biological species in our

spaceship ecosystem, but we forget that even the mountains and rocks pass through their natural life

cycles and are banished into time past.

These pseudotektites are the final survivors of their ancestral volcanic parents in the geologic Garden of

Eden. As the strongest bits in the hearts of boulders, they are something of a crowning gem (---and the

gemmy transparent lilac ones do indeed facet into spectacular jewels!). Hold one and marvel. It is not a

tektite. It doesn’t need to be. It is a stone with its own amazing story. It is one of the final generation

of its kind before ultimate extinction. A grandfather boulder-heart!

A gem Colombianite!

Meteorite Times Magazine

Understanding the Early Solar System through the Analysis of Meteorites: TheProcess of Maximizing Data while Minimizing Sample DestructionEllen J. Crapster-Pregont

Ellen J. Crapster-Pregont1,2

1.Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, 10964, USA.2.Dept. of Earth and Planetary Science, American Museum of Natural History, New York, NY, 10024,USA.

Every year approximately 40,000 meteorites make it to Earth’s surface. This value is based on cameranetwork meteor data (Halliday et al., 1989; Bland, 2005) and weathering studies of hot desert meteorites(Bland et al., 1996a,b; Bland, 2005) for stones ranging f rom 10 to 106 g in mass. Of these, less than 10%are greater than 1 kg and less than 1% are collected, classif ied, and named (Fig. 1; based on values inBland (2005) and the Meteoritical Society Bulletin Database). This small percentage is af fected by ourinability to retrieve many samples, such as ocean falls, and by surface survival rates. Figure 1 breaks downthis small percentage a step further to highlight how valuable chondrites, or meteorites f romundif ferentiated parent bodies, are considering the information they hold about the highest temperaturechemistry and processes in the protoplanetary disk as it started cooling and condensing, transitioning f romgas and dust to crystalline solids, particularly the ref ractory (i.e. formed at high temperature) componentsobserved in chondrites such as calcium- and aluminum-rich inclusions. These components preserve themost primitive information about our early solar system, and, as Figure 1 implies, only a small percent of asmall percent of collected and classif ied meteorites contain this valuable information.

One of the greatest goals of a planetary scientist is to piece together chemical environments and physicalprocesses that operated in our early solar system producing the planets and bodies that exist today. Thisis a Herculean task as much of the evidence lacks context or ref lects a more recent, alteration ordeformation history. Chondrites have bulk chemistries similar to that of the sun and preserve the history ofthe protoplanetary disk (i.e. gas and dust distributed in a disk-like fashion around a proto-sun prior toplanet formation) and their parent body within their components. Similar to other valuable meteorite groups,the subsets of chondrites with highest scientif ic value are only available for research in small quantities. Itis, therefore, important to maintain a delicate balance between sample preservation and contributing to thescientif ic knowledgebase f rom collection and curation through analysis. A combination of non-destructivetechniques through the entire sequence f rom sample selection, preparation, and analysis maximizesscientif ic return while minimizing material loss.

So what exactly can chondrites tell us? To answer this, we f irst have to consider the variety ofcomponents that make up chondrites (Fig. 2). These components are categorized broadly as: calcium- andaluminum-rich inclusions (CAI), amoeboid olivine aggregates (AOA), chondrules, metal and sulf ide nodules,and matrix. CAIs are highly ref ractory containing the greatest abundance of elements (i.e. Ca, Al, Ti) thatcondense f rom a vapor at high temperature, and minerals (e.g. corundum, hibonite, spinel, melilite) formedat high temperatures in the protoplanetary disk. CAIs exhibit a range of textures f rom primitive aggregatesof tiny mineral grains to completely melted and recrystallized. AOAs typically have a core of highlyrefractory, CAI-like material but are then surrounded by olivine, a Mg-Si mineral that condenses at lowertemperatures than the minerals in CAIs. As their name indicates, their texture is f ragmented and clustered,with many of the olivine-rimmed refractory clumps arranged together at dif fering scales. Chondrules arediverse in composition but contain mainly Mg-Si minerals with varying Fe included to a varying degree.Many chondrules appear to have been completely melted prior to accretion while some may ref lect a lessmelted, more agglomerated formation. Metal, generally Fe-Ni alloy, and sulf ides can be common or raredepending on the conditions of chondrite formation. Matrix is the f ine-grained material that holds all thechondrite components together. The percentage varies between types of chondrites and it is the mostsusceptible component, af ter metal and sulf ides, to the ef fects of terrestrial alteration.

Dif ferent components and aspects of each component yield diverse information pertaining tocharacteristics of the early solar system and processes on parent bodies. Primitive, unmelted, CAI materialholds the highest temperature record within its chemistry taking us back to a high-temperatureprotoplanetary disk (e.g. Ebel and Grossman, 2000; Grossman, 2010). Isotopic compositions can revealthe ages of components and def ine chemical reservoirs (e.g. Krot et al., 2005; Connelly et al., 2012; Holst

et al., 2013). Composition, crystallization characteristics, and other features def ine the melting histories ofcomponents’ precursors including the temperature, duration, and extent of heating and potential formationprocesses (e.g. Jones and Rubie, 1991; Ebel et al., 2008; Krot and Bizzarro, 2009; Desch et al., 2010;Asphaug et al., 2011; Hubbard et al., 2012; Sanders and Scott, 2012; Johnson et al., 2015). Metal andiron content of certain minerals ref lect how oxidizing or reducing conditions were and whether thiscondition varied in space or time (e.g. Connolly et al., 2001; Beck et al., 2012; Schrader et al., 2013). Sizeand abundance distributions of components among dif ferent chondrite types distinguish unique f romshared histories among chondrite types (e.g. Cuzzi et al., 2001; Hezel and Palme, 2010; Friedrich et al.,2014). These are just a few examples of critical datasets and their potential implications. All in, chondriticcomponents’, chemistry, proportions, textures, etc. provide constraints for the protoplanetary disk thatastrophysicists try to model and for the pre-dif ferentiation parent body processes in the early solarsystem.

Chondrites clearly contain a wealth of information that provides insight into the conditions of theprotoplanetary disk and parent bodies even if only small percentages are recovered. A majority ofmeteorites studied today are collected through organized ef forts, such as the Antarctic Search forMeteorites, which focus on sites in hot and cold deserts where meteorites are both preserved longer andcan be concentrated. Terrestrial weathering essentially removes value f rom a sample as it alters much ofthe chemical and mineralogical information to ref lect recent Earth surface rather than early solar system orchondrite parent body conditions. Falls are the most preferred specimens but are rare (Fig. 1), do notencompass all types of meteorites, and still suf fer f rom terrestrial weather ef fects. To the planetaryscience research group at the American Museum of Natural History (AMNH) is guided by the thought thatevery meteorite sample should be handled and curated in a way that extracts as much information aspossible about every aspect of the meteorite while preserving the sample for future use (Fig. 3), especiallythose samples that contain rare, valuable data about the early solar system.

At the AMNH, the analysis protocol for recent work begins with a trip to the in-house CT scanner (GEVtomeX-S x-ray computed tomography scanner) in the Microscopy and Imaging Facility. This instrumentutilizes high-powered x-rays to produce data that is reconstructed into a 3-dimensional (3D) density mapof the sample. Obtainable resolution, measured as the edge length of each cubic volume element, or‘voxel’, depends on sample size, or distance f rom source, and size of focal spot; i.e. the best resolutionfor a sample 5x5x20 mm is ~4 micron/voxel on the scanner at AMNH (Fig. 3A and B). Resolution limits thetypes of analyses that can be conducted. Lower resolution allows virtual isolation (segmentation) andquantif ication of materials with signif icantly dif ferent densities (i.e. metals vs. silicates or chondrules vs.matrix) while higher resolution studies can dif ferentiate dif ferent silicate and oxide minerals (e.g. Ebel etal., 2008; Friedrich and Rivers, 2013; Russell and Howard, 2013; Tsuchiyama et al., 2013). The 3Dvisualization permits analyses done in 2D to be placed into context (i.e. whether the mineral is in the coreor rim of the chondrule) which could greatly af fect interpretations. Component relationships andabundances can also be directly calculated f rom the CT data (e.g. Friedrich and Rivers, 2013; Russell andHoward, 2013; Goldman et al., 2014). While this technique can guide sample preparation, 2D analyses ofsurfaces are still required to address a majority of the component-based protoplanetary disk and parentbody processes conundrums.

During sample preparation, cutting is the step that results in the most unrecoverable sample loss. Typicaldiamond embedded rock-cutting blades lose a >100 micron thick slice of material. Use of a 20, 30 or 50micron tungsten (W) wire saw (Princeton Instruments) minimizes the thickness of material lost. Thisef fectively minimizes sample loss and maximizes the number of surfaces that can be analyzed within agiven piece of meteorite, a method called ‘serial sectioning’ (Fig. 3C; ps1B and ps2A are cut surfaces).This technique permits >100 micron diameter components to be exposed on two mirrored cut surfaceswhile larger components can be sectioned in more than two adjacent sets of surfaces (e.g. Ebel et al.,2008). The wire saw also produces a smooth surface requiring minimal grinding when the sample ispolished for analysis.

Polishing is necessary to reduce surface topography which negatively af fects most analysis techniques.Some techniques, such as electron microprobe (EMP) analysis, require a polish f inished with 1 or 0.25micron diamond solutions, while others, such as electron backscatter dif f raction (EBSD), require extremelygood polishes adding a chemical etching component with the use of colloidal silica. Diamond is a preferredpolishing compound because it does not contaminate the sample with aluminum (Al) or silicon (Si) bothwhich are of interest for components in chondrites. Alcohol or mineral spirits are preferred over water forpolishing and rinsing because water may cause oxidation, reactions, or dissolution of some minerals.Successfully prepared samples can be coated with a thin layer of carbon to make them conductive, a

necessity for use in most electron beam instruments.

The Cameca SX100 EMP at AMNH uses two types of spectrometers: wavelength dispersive and energydispersive, to generate elemental concentration data for individual points or regions. Pixel-by-pixel elementintensity maps (Fig. 3D) can be combined into red-green-blue (RGB) composites allowing dif ferentiationbetween types of inclusions and minerals in meteorites over large, region maps (>1 micron/pixel) orindividual inclusions (1 micron/pixel). Figure 2 illustrates zoom in of dif ferent components and f igure 3Eshows a component of interest outlined in white. Element intensities measured by the EMP are convertedto oxide weight percent (wt%) via calibration against standards analyzed with the same instrument settingsas the samples. A variety of sof tware, either customized or packaged, can be used to evaluate eachinclusion pixel-by-pixel using element intensity maps and combinations of ratios and cation formulas. Aphase map is produced with each pixel assigned a false color indicating mineralogy as determined byelement intensities (Fig. 3F). Bulk chemistry, mineralogy, modal abundance, texture, and area arequantif iable f rom either region or individual inclusion maps (Fig. 3G). The choice of analysis sof tware willaf fect the time required for sample preparation, calibration, data acquisition, and image analysis and thischoice is made based on the scale and focus of the study.

Up to this stage of analysis the techniques (CT, wire saw, polishing, EMP) are minimally destructive to thevaluable samples. The data are used to evaluate and compare chondrite component characteristicsincluding chemical composition, mineralogy, and textures. So, with minimal sample loss many scientif icquestions (major element chemical environments, abundances of components in chondrites, the mineralogyof chondrite components etc.) regarding the protoplanetary disk and parent body processes can begin tobe addressed. Our group uses this protocol to build databases that provide contextual and quantif iableinformation about the early solar system that is accessible for reevaluation in the future. This preservesmaximum data for the limited primitive, pristine chondritic samples that have been collected andcatalogued.

This database serves as a resource for directing further analyses which can be more destructive or costprohibitive (Fig. 3H). Electron backscattered dif f raction (EBSD) provides crystal orientation informationwhich is used to understand crystallization and deformation of mineral grains. Figure 4 depicts preliminaryEBSD data that highlights twinning in metal found in a chondrule which will provide formation constraints(e.g. Crapster-Pregont et al., 2015). Secondary ion mass spectrometry (SIMS) is minimally destructive butmay require travel and analysis costs as not all institutions maintain these instruments. Inductively coupledmass spectrometry (ICP-MS) requires either dissolving the sample into solution or blasting the point ofinterest with a laser while both can be done with minimal sample loss, this method may also require extracost. Both SIMS and ICP-MS yield information about trace element abundances and even isotopicinformation yielding constraints on reservoirs and ages (e.g. Stracke et al., 2012; McCubbin et al., 2014)for SIMS and ICP-MS respectively). Focused ion beam lif tout for transmission electron microscopy (FIB-TEM) can be used for extremely high-resolution chemical and orientation analysis of relationships withinand among minerals within a chondrite component (e.g. Stroud et al., 2002; Stroud et al., 2003). EBSD,SIMS, ICP-MS, and FIB-TEM are just a few techniques implemented by planetary scientists to obtaindetailed data f rom chondrites to continue addressing questions about the early solar system. However,unlike the protocol described above, each of these techniques requires sample consumption to producedata. While valuable sample is lost, the initial context and basic information f rom the chondrite is preservedin datasets f rom the minimally destructive analysis techniques.

Even though fewer meteorite samples exist in a catalogued database than are predicted to fall in a year, itis possible to optimize the analysis process with respect to the value of the chondrite and the information itcontains. When combined these techniques (Fig. 3) reduce the amount of material lost and maximize theinformation obtained f rom a single meteorite sample. The larger set of data preserves contextual andquantif iable data for each CAI, AOA, chondrule, metal nodule, and matrix while guiding future, destructiveanalysis. By using a series of instruments, visualizations, and sof tware protocols it is possible to begin tobetter understand the complexity of the protoplanetary disk, and planet formation processes preserved inmeteorites with maximum conservation of these precious samples.

Acknowledgments: The Brian Mason Travel Award is sponsored by the International Meteorite CollectorsAssociation for the 2015 78th Annual Meteoritical Society Meeting. Research is supported by the NationalScience Foundation Graduate Research Fellowship Program grant DGE-11-44155 and NASACosmochemistry grant NNX10AI42G.

Fig. 1: Percentage bar representations demonstrate the rarity of and necessity to fully analyze chondritesand their components. Percentages for predicted annual impacts of meteorites (Bland, 2005) are fargreater than those collected, classif ied, and catalogued (top bar: 2014 data f rom the Meteoritical SocietyBulletin Database). When all meteorites in the Database are considered the remaining percentage barcomparison show: iron, achondrite, or chondrite; whether a f ind or the much less common observed fall;exhibiting parent body alteration or pristine; and whether the component is composed of minerals predictedto condense at highest temperature (ref ractory) in the protoplanetary disk. All percentages are based onnumber not mass.

Fig. 2: Backscattered electron image (BSE) of Moss (CO3.6) AMNH #5185 with examples of dif ferentcomponents boxed with corresponding outset false color, 3-element red-green-blue composite images.The 3-element combination Mg-Ca-Al clearly distinguishes calcium- and aluminum-rich inclusions (CAI;primarily blue and green), chondrules (primarily red), and amoeboid olivine aggregates (AOA; blue andgreen core with red surrounding) f rom each other. While metal appears black in the Mg-Ca-Al images thecombination of Fe-Ni-S permits chemical variation observation for the metal nodules and metal in the AOA.Matrix is a darker red color highlighted in the white box within the corresponding image of a dif ferentcomponent.

Fig. 3: Preparation and analysis protocol for minimizing sample loss and maximizing data. (A) Photo ofMoss (CO3.6) AMNH #5185; (B) single CT slice, high density is whitest; (C) post-wire saw sections; (D)EMP element intensity maps for aluminum (Al), calcium (Ca) and magnesium (Mg) with inclusion outlined;(E) RGB composite, note ease of distinguishing inclusion; (F) false color mineral map output: purple-spinel,red-olivine (olv), green-clinopyroxene (cpx); (G) quantitative data produced; (H) further destructivetechniques possible using a high level of prior contextual knowledge (A-G).

Fig. 4: Electron backscatter dif f raction (EBSD) generated false color, reverse pole f igures maps for awhole metal nodule (a; 2 μm/pixel) and higher resolution portion of a dif ferent nodule (b; 0.5 μm/pixel) inthe second metal layer in the Acfer 139 layered chondrule. Color represents the orientation of the metal ateach pixel described by the mixing chart in the center of the f igure where each apex is a dif ferent crystalaxis. Small wire-f rame cubes highlight the orientation of various regions. Lamellar-like features are twinningnot artifacts of the polishing process. Image unmodif ied f rom (Crapster-Pregont et al., 2015) withpermission.

References:

Asphaug E., Jutzi M. and Movshovitz N. (2011) Earth and Planetary Science Letters. Earth andPlanetary Science Letters 308, 369–379.

Beck P., De Andrade V., Orthous-Daunay F. R., Veronesi G., Cotte M., Quirico E. and Schmitt B. (2012)The redox state of iron in the matrix of CI, CM and metamorphosed CM chondrites by XANESspectroscopy. Geochimica et Cosmochimica Acta 99, 305–316.

Bland P. A. (2005) The impact rate on Earth. Philosophical Transactions of the Royal Society A:Mathematical, Physical and Engineering Sciences 363, 2793–2810.

Bland P. A., Berry F. J., Smith T. B., Skinner S. J. and Pillinger C. T. (1996a) The f lux of meteorites to theEarth and weathering in hot desert ordinary chondrite f inds. Geochimica et Cosmochimica Acta 60,2053–2059.

Bland P. A., Smith T. B., Jull A. J. T., Berry F. J., Bevan A., Cloudt S. and Pillinger C. T. (1996b) The f luxof meteorites to the Earth over the last 50 000 years. Monthly Notices of the Royal Astronomical Society283, 551–565.

Connelly J. N., Bizzarro M., Krot A. N. and Nordlund Å. (2012) The absolute chronology and thermalprocessing of solids in the solar protoplanetary disk. Science 338, 651–655.

Connolly H. C. Jr, Huss G. R. and Wasserburg G. J. (2001) On the formation of Fe-Ni metal in Renazzo-like carbonaceous chondrites. Geochimica et Cosmochimica Acta 65, 4567–4588.

Crapster-Pregont E. J., Towbin W. H. and Ebel D. S. (2015) Metal-Centric Perspective of a LayeredChondrule in the CR Chondrite Acfer 139: Insights f rom Electron Backscattered Dif f raction. Lunar andPlanetary Science Conference Proceedings. Abstract #1561.

Cuzzi J. N., Hogan R. C., Paque J. M. and Dobrovolskis A. R. (2001) Size-selective concentration ofchondrules and other small particles in protoplanetary nebula turbulence. ApJ 546, 496–508.

Desch S. J., Morris M. A., Connolly H. C. and Boss A. P. (2010) A Critical Examination of the X-WindModel for Chondrule and Calcium-Rich, Aluminum-Rich Inclusion Formation and Radionuclide Production.ApJ 725, 692–711.

Ebel D. S. and Grossman L. (2000) Condensation in dust-enriched systems. Geochimica etCosmochimica Acta 64, 339–366.

Ebel D. S., Weisberg M. K., Hertz J. and Campbell A. J. (2008) Shape, metal abundance, chemistry, andorigin of chondrules in the Renazzo (CR) chondrite. Meteoritics and Planetary Science 43, 1725–1740.

Friedrich J. M. and Rivers M. L. (2013) Three-dimensional imaging of ordinary chondrite microporosity at2.6 micron resolution. Geochimica et Cosmochimica Acta 116, 63–70.

Friedrich J. M., Weisberg M. K., Ebel D. S., Biltz A. E., Corbett B. M., Iotzov I. V., Khan W. S. and WolmanM. D. (2014) Chondrule size and related physical properties: A compilation and evaluation of current dataacross all meteorite groups. Chemie der Erde – Geochemistry, 1–25.

Goldman R. T., Crapster-Pregont E. J., and Ebel D. S. (2014) Comparison of Chondrule and CAI SizeMeasured by Electron Microprobe (2D) and Computed Tomography (3D). Lunar and Planetary ScienceConference Proceedings. Abstract #2263.

Grossman L. (2010) Vapor-condensed phase processes in the early solar system. Meteoritics andPlanetary Science 45, 7–20.

Halliday I., Blackwell A. T. and Grif f in A. A. (1989) The f lux of meteorites on the Earth’s surface.Meteoritics 24, 173–178.

Hezel D. C. and Palme H. (2010) The chemical relationship between chondrules and matrix and thechondrule matrix complementarity. Earth and Planetary Science Letters 294, 85–93.

Holst J. C., Olsen M. B., Paton C., Nagashima K., Schiller M., Wielandt D., Larsen K. K., Connelly J. N.,Jorgensen J. K., Krot A. N., Nordlund Å. and Bizzarro M. (2013) 182Hf–182W age dating of a 26Al-poorinclusion and implications for the origin of short-lived radioisotopes in the early Solar System. InProceedings of the National Academy of Sciences of the United States of America. pp. 8819–8823.

Hubbard A., McNally C. P. and Mac Low M.-M. (2012) Short Circuits in Thermally Ionized Plasmas: AMechanism for Intermittent Heating of Protoplanetary Disks. ApJ 761, 58.

Johnson B. C., Minton D. A., Melosh H. J. and Zuber M. T. (2015) Impact jetting as the origin ofchondrules. Nature 517, 339–341.

Jones R. H. and Rubie D. C. (1991) Thermal histories of CO3 chondrites: application of olivine dif fusionmodelling to parent body metamorphism. Earth and Planetary Science Letters 106, 73–86.

Krot A. N. and Bizzarro M. (2009) Chronology of meteorites and the early solar system. Geochimica etCosmochimica Acta 73, 4919–4921.

Krot A. N., Yurimoto H., Hutcheon I. D. and MacPherson G. J. (2005) Chronology of the early SolarSystem f rom chondrule-bearing calcium-aluminium-rich inclusions. Nature 434, 998–1001.

McCubbin F. M., Shearer C. K., Burger P. V., Hauri E. H., Wang J., Elardo S. M. and Papike J. J. (2014)Volatile abundances of coexisting merrillite and apatite in the martian meteorite Shergotty: Implications formerrillite in hydrous magmas. American Mineralogist 99, 1347–1354.

Russell S. S. and Howard L. (2013) The texture of a f ine-grained calcium-aluminium-rich inclusion (CAI) inthree dimensions and implications for early solar system condensation. Geochimica et CosmochimicaActa 116, 52–62.

Sanders I. S. and Scott E. R. D. (2012) The origin of chondrules and chondrites: Debris f rom low-velocityimpacts between molten planetesimals? Meteoritics and Planetary Science 47, 2170–2192.

Schrader D. L., Connolly H. C. Jr, Lauretta D. S., Nagashima K., Huss G. R., Davidson J. and Domanik K.J. (2013) The formation and alteration of the Renazzo-like carbonaceous chondrites II: Linking O-isotopecomposition and oxidation stateof chondrule olivine. Geochimica et Cosmochimica Acta 101, 302–327.

Stracke A., Palme H., Gellissen M., Münker C., Kleine T., Birbaum K., Günther D., Bourdon B. and Zipfel J.(2012) Refractory element f ractionation in the Allende meteorite: Implications for solar nebulacondensation and thechondritic composition of planetary bodies. Geochimica et Cosmochimica Acta 85,114–141.

Stroud R. M., Long J. W., Swider-Lyons K. E. and Rolison D. R. (2002) Transmission electron microscopystudies of the nanoscale structure and chemistry of Pt50Ru50 electrocatalysts. Microscopy andMicroanalysis 8, 50–57.

Stroud R. M., Nittler L. R., Alexander C. M., Bernatowicz T. J. and Messenger S. R. (2003) Transmissionelectron microscopy of non-etched presolar silicon carbide. Lunar and Planetary Science ConferenceXXXIV. Abstract #1755.

Tsuchiyama A., Nakano T., Uesugi K., Uesugi M., Takeuchi A., Suzuki Y., Noguchi R., Matsumoto T.,Matsuno J., Nagano T., Imai Y., Nakamura T., Ogami T., Noguchi T., Abe M., Yada T. and Fujimura A.(2013) Analytical dual-energy microtomography: A new method for obtaining three-dimensional mineralphase images and its application to Hayabusa samples. Geochimica et Cosmochimica Acta 116, 5–16.

Meteorite Times Magazine

Bilanga MeteoritePaul Harris

Our Meteorite of the Month is kindly provided by Tucson Meteorites who hostsThe Meteorite Picture of the Day.

Bilanga 127 grams. Contributed by Anne Black, IMCA 2356

Submit Pictures to Meteorite Pictures of the Day

catchafallingstar.com Nakhla Dog Meteorites

Michael Blood Meteorites The Meteorite Exchange

Impactika Rocks From Heaven

Aerolite Meteorites Big Kahuna Meteorites

Sikhote-Alin Meteorites Michael Farmer

Meteorite Times MagazineMeteorite-Times Sponsorsby Editor

Please support Meteorite-Times by visiting our sponsors websites. Clickthe bottom of the banners to open their website in a new tab / window.

Schoolers Nevada Meteorites

Advertise Here

Once a few decades ago this opening

was a framed window in the wall

of H. H. Nininger's Home and

Museum building. From this

window he must have many times

pondered the mysteries of

Meteor Crater seen in the distance.

Photo by © 2010 James Tobin