rvcc geol 157 introduction to geology - impacttectonics.org gch geol157 lab2.pdf11 th laboratory...

RVCC GEOL 157 Introduction to Geology

Professor Gregory C. Herman [email protected] Manual

GCH 2018-01

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Sources noted within

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RVCC GEOL 157 Introduction to Geology Lab Manual GCH 2018-01


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• LAB ROOM SC-219 is set up with five (5) student tables with four seat each.

•One Fischer-Scientific stereo microscope will be furnished per table during mineral

and rock labs.

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PROJECTOR

LECTURN

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LAB ROOM SC-219 is set up with five tables, four seats per table.

• Laptop PCs are available to students if they do not have one or cannot use their own.

Use of one’s own lap top is encouraged, as is the use of a optical mouse with a wheel

(USB or Bluetooth) for Google Earth labs.

Paired

wide-field

eyepieces

Adjustable

magnification

by rotating

the

adjustable

turret

Adjustable

left eyepiece

for focus

Adjustable

knob used

to lower and

raise the

microscope

head

stage

Fischer-Scientific T1A

STEREO MICROSCOPE


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Can transmit

plain white

light from

above or

below the

object placed

on stage (light switches

not shown)

• This lab is an introduction to minerals and spectroscopy, the latter being the

scientific study of how light interacts with solid matter.

Minerals comprise Earth materials and are formed by :

1) the cooling of melted Earth material (molten magma) in Earth’s crust (solid) and

2) the precipitation of minerals from either

a) saturated, briny fluids (including microcrystalline forms of quartz and calcite) or

b) biological accretion (seashells)

By the end of this lab you should have a working familiarity with the most-common rock

forming minerals, including the 5 most abundant silicate rock-forming minerals (quartz,

feldspar, mica, amphibole, and pyroxene) that comprise Earth’s crust. We will identify them

separately from other common minerals that appear similar but are usually softer and formed

from precipitation .

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Laboratory 2. Minerals and Spectroscopy

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Laboratory 2. Minerals

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Exercise 1. Handle and identify the 10

most common rock-forming minerals


• Carbonates (CO3)-2

•Sulfates (SO4)-2

•Phosphates (PO4)-3

Calcite (CaCO3) is the

main constituent in the

sedimentary rock

limestone

Gypsum (CaSO4 . H4O) is a main

constituent in drywall

Turquoise CuAl6(PO4)4(OH)8·5H2O

derived from the shells and hard parts of marine organisms or are precipitated

as seawater evaporates

derived from hydrothermal activity or

are precipitated as saline-water

evaporates

derived from hydrothermal

activity and igneous processes

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Laboratory 2. Mineral Cleavage

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http://slideplayer.com/slide/8711262/26/images/9/Types+of+Cleavage.jpg

Laboratory 2. Mineral Cleavage Types

Mohs Hardness Scale

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Laboratory 2.

Minerals

Adapted from Cronin,

V. S., and Tasa, D.,

11th Laboratory

Manual in Physical

Geology: Pearson,

New York, NY, 426 p.


Silicate Minerals

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Quartz – No. 2 of the 5 most common rock-forming (silicate) minerals

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• Identify quartz, calcite, and gypsum by checking the type of habit, cleavage,

and visual aspects that you observe

Quartz (silica SiO4)

Calcite (carbonate CaCO3)

Gypsum (sulfate SiO4)

NOTES:

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• Group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust.

•Two cleavage directions at 900.

•Hardness of 6 – 6.5.

•Will not scratch glass or quartz.

•Microcline and orthoclase

•Not usually clear.

•Often salmon pink or white and milky.

•Can also be aqua blue.

•Can have wavy stripes of similar color that go through the mineral.

Alkali feldspars (K,Na)AlSi3O8

Plagioclase feldspars (Na,Ca)AlSi3O8

•Albite to Anorthite solid-solution series

•Individual crystals a range of colors between white and dark gray.

•Exhibits striations

•Can have wavy stripes of similar color that go through the

mineral.

www.earthguide.ucsd.edu/mystery_detectives/media/flash/minerals_igneous/minerals_igneous.swf

FELDSPAR – No. 1 of the 5 most common rock-forming (silicate) minerals

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• Identify plagioclase and alkali feldspar by color, microscopic twinning, and

mineral habit, hardness with respect to quartz and metal. Note any visual

and physical aspects that you observe.

Plagioclase feldspar (silicate (Na,Ca)AlSi3O8)

Twinning seen on face of large plagioclase sample

Alkali feldspar (K,Na)AlSi3O8)

NOTES:

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Cleavage habitLaboratory 2. Minerals

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Cleavage habitLaboratory 2. Minerals

• Identify the following minerals by color, and mineral habit, hardness with

respect to quartz and metal and one another. Note any distinctive visual and

physical aspects that you observe.

Mica (biotite and muscovite)

Pyroxene

Amphibole

Olivine/peridotite

NOTES:

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Laboratory 2 – Part B Spectroscopywww.impacttectonics.org/Gcherman/downloads/PHY120C/

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For this exercise, pick 3 minerals out of the box and use your manual and the Internet

to make your best guess as to what it is. Write the name and a chemical formulae down.

Color

Habit

Cleavage

Hardness

Weight

Streak

Magnetic

Notes:

Name

Chemical

Formuale

Sample 1 Sample 2 Sample 3

Laboratory 2. Minerals Pick 3 Exercise

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Exercise 1. Identify the 10 most

common rock-forming minerals

Gypsum

(Alabaster) Muscovite

(mica)

Gypsum

(crystalline)

Calcite

(spar)Halite

Plagioclase

feldspar

Milky

quartz

Quartz crystals

Alkali

feldspar

(Orthoclase)

Pyroxene

(Augite)

Amphibole

(Hornblende)


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1) Igneous are derived from the hardening of

molten magma (intrusive or volcanic, with felsic,

intermediate, and mafic varieties)

2) Sedimentary are derived from detrital or

chemical sediment, the products of mechanical

and chemical weathering and chemical

precipitation.

3) Metamorphic are the result of burial,

increasing temperature and pressure, and fluid

transfer processes during recrystallization

(low, medium, and high grade)


• Igneous rock forms when hot magma cools and solidifies. Sedimentary rocks form when

sediment is compacted and cemented together (lithified), or when minerals precipitate from

solutions. Mechanical weathering and physical breakdown of a parent material (usually rock)

produces clastic or detrital sediment, whereas chemical sediment is accreted through

biological processes or precipitates directly from hydrothermal or briny waters. Metamorphic

rocks are compacted, heated, pressurized, and altered from burial, thermal contact, and fluid

transfer during recrystallization and alteration.

rvcc geol 157 introduction to geology - impacttectonics.org gch geol157 lab2.pdf11 th laboratory...

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