Geology Midterm

Question 1

magma?

Answer 1

under earths surface

Question 2

lava?

Answer 2

out of the earths surface

Question 3

extrusive?

Answer 3

Extrusive rocks are formed on the surface of the Earth from lava,

Question 4

intrusive?

Answer 4

Intrusive rocks are formed from magma that cools and solidifies within the crust of the planet.

Question 5

Felsic

Answer 5

rich in feldspar and silicon. (granite)

Question 6

Intermediate

Answer 6

andesite, dacite, and trachyandesite among volcanic rocks and diorite and granodiorite among plutonic rocks.

Question 7

Mafic

Answer 7

pyroxene, amphibole, olivine, and mica.

Question 8

ultramafic

Answer 8

An igneous rock with extremely low silica composition, being made of almost all olivine and pyroxene

Question 9

quartz

Answer 9

chemically inert in contact with most substances. It has electrical properties and heat resistance that make it valuable in electronic products. Its luster, color, and diaphaneity make it useful as a gemstone and also in the making of glass.

Question 10

orthoclase

Answer 10

Colorless, greenish, greyish yellow, white, pink
Streak white
Luster Vitreous, pearly on cleavage surfaces
Cleavage Has perfect cleavage on {001} and good cleavage on {010}. Cleavages intersect at 90°. It can be difficult to see cleavage in thin section due to orthoclase’s low relief.

Question 11

pyrite

Answer 11

brassy metallic luster, black streak, brittle fracture, hardness greater than that of glass, absence of cleavage and it is nonmagnetic.

Question 12

hematite

Answer 12

Its luster can range from earthy to submetallic to metallic. Its color ranges include red to brown and black to gray to silver. It occurs in many forms that include micaceous, massive, crystalline, botryoidal, fibrous, oolitic, and others. RED STREAK

Question 13

olivine

Answer 13

high retardation, distinctive fracturing, lack of cleavage, and alteration to serpentine. Colorless to olive green in thin section.

Question 14

garnet

Answer 14

lack cleavage but tend to be brittle.

Question 15

muscovite

Answer 15

perfect cleavage allows it to be split into thin, flexible, elastic, colorless, transparent sheets with a pearly to vitreous luster

Question 16

biotite

Answer 16

highly perfect basal cleavage, and consists of flexible sheets, or lamellae, which easily flake off.

Question 17

plagioclase

Answer 17

Vitreous. Pearly on some cleavage faces.
Cleavage Perfect in two directions that intersect at approximately 90 degrees.
Diaphaneity Translucent to transparent

Question 18

sulfur

Answer 18

rotten eggs

Question 19

halite

Answer 19

SALTY clear

Question 20

calcite

Answer 20

looks like calcium, reacts to acid

Question 21

talc

Answer 21

soft, soapy

Question 22

graphite

Answer 22

high resistance to high temperatures and chemicals, excellent thermal and electrical conductivity, and resistance to friction and wear.

Question 23

amphibole

Answer 23

iron content affects color

Question 24

galena

Answer 24

high specific gravity, HEAVY

Question 25

fluorite

Answer 25

four directions of perfect cleavage, often breaking into pieces with the shape of an octahedron.

Question 26

kaolinite

Answer 26

CHALK soft

Question 27

magnetite

Answer 27

magnetic