Meteorites

Fragments of the Solar System

• Dedicated toDr. Elbert King– First director of

the LunarReceiving Lab

– Recovered alot of Allende!!

– Meteoriticist

Meteorites

• Meteoroids– “small” rocks orbiting in space

• Meteors– “rocks” entering the atmosphere and glowing– Most are the size of a grain of sand– Some are a lot bigger!!!

• Meteorites– Rocks from space that have hit the Earth

Thunderstone of Ensisheim

• 1492

Thunderstone of EnsisheimWhat’s left of it

• What Holbrook supposedly looked like

1946

• Famous painting of the Shikote-Alin meteorite on a USSR postage stamp.

Meteorites• Irons iron + nickel

• Stoney Irons– Mesosiderites MES silicate + iron– Pallasites PAL iron + silicate (olivine)

• Stoney– Chondrites silicate + some iron (sometimes)

• Ordinary Chondrites H, L, LL• Carbonaceous Chondrites C, CO, CV, CM, CK• Others – Enstatite Chondrites E – Rumruti R

– Achondrites• HED – from Vesta• SNC – from Mars• ALUN – from the Moon

Irons

• Cape York – “discovered” by Peary

fromGreenland

actuallydiscovered bylocal Inuit

Irons

Irons

Irons

• Witmanstatten Patterns

• Gibeon

Irons

• Willamette

Irons

• Hoba – 60 tons

• Campo del Cielo

Stony Irons

• Mesosiderites - MES

• Silicate based – with a lot of metal running through it.

• NWA1879

Stoney Irons

• Another mesosiderite-MES

Stoney Irons

• Mesosiderite Morristown

Stoney Iron• Pallasites

• Iron based – with olivine crystals sprinkled through

• Thought tobe from the core-mantleboundary ofthe parentasteroid

Stoney IronPallasite – lit from behind

Stoney - Chondrites• Ordinary Chondrites

– H (High Metal) – L (Low Metal) – LL (Very Low Metal)

• Inside (Brecciated) Outside (Crusted)

Probably a L4-5 – this comes from NWA – Morocco

Chondrules / Chondrites

Stoney - Chondrites

• Carbonaceous chondrites– Residue from the formation of the Solar

System – 4.5+ Billion Years old

Allende – CV3.2Murcheson – CM2

Stoney - Achondrites

• HED Howardite

• DAG 844

Meteorites from Asteroid 4 Vesta

Stoney - Achondrites

• HED Eucrite

• Millbillillie

Stoney - Achondrites

• HED Diogenite

• Johnstown

Stoney - Achondrites

• SNC Shergottite

• Zagami

Meteorites from Mars

Stoney - Achondrites

• SNC

Dhofar 019

DAG 476

Stoney - Achondrites

• ALUN

• DAG 400

Meteorites from the Moon

How do we know they are from Mars / the Moon / 4 Vesta??

• Mars: Viking 1 and 2 had soil and atmosphere analyzers. The percentages of the elements and isotopes are the same as the SNC meteorites – and different from others!

• The Moon: Same story – except we have real moon rocks to compare them to

• Vesta: Spectroscopy of Vesta indicates it is made of HED materials, and no other asteroid is. Recent studies show a great crater on Vesta where some of these materials must have been ejected from.

How to Study Meteorites

• What does it look like (big picture)

• What does it look like (microscope)

• What elements are in it (chemistry and microprobe)

• What isotopic ratios are there (microprobe)

• Where did it come from (compare to asteroids and planets)

• How did it fall (distribution)

Meteorites / Meteorwrongs

• Meteorites are not hot when they hit the earth!• Almost all meteorites are magnetic!• Almost all meteorites have some visible metal

(though sometimes only a little).• Most meteorites are denser than local rocks.• Meteorites don’t have holes/bubbles in them.• For real analysis you have to take it to an expert

How to Study Meteorites

• Thin Sections – The coolest way to look at meteorites is in “thin section”. Take a thin slice of the rock, glue it to a microscope slide and grind/polish it until it is 30 micrometers thick. You can then look at it under a “petrographic microscope” with crossed polarizing filters. The colors tell you the minerals!

Eucrite Enstatite

Richfield LL3.7

Pultusk

• SNC

Some chondrules in thin section

Eucrite thin section

• Looks a lot like Kilauea basalts!

Apollo 17 Basalt

Apollo 12 Basalt

Impact!!!• When a Big rock hits – 50

meters or more – it can make a rather big hole in the ground!!!!

Meteor Crater

Wolf Creek

Lake Manicoagan

Chixilub

Brent Crater

Pretoria “Saltpan”

Sudbury + Lake Wanapitei

DisclaimerAloha

I put together these power points for use in my science classes.You may use them in your classes.

Some images are public domain, some are used under the fair-use provisions of the copyright law, some are mine. Copyright is retained by the owners!

Ted Brattstrom