Igneous Rocks

Question 1

igneous rocks

Answer 1

rocks that form from the cooling and crystallization of magma or lava

Question 2

why don’t pumice and scoria look like obsidian since they are also glassy?

Answer 2

air bubbles were able to escape the rock during cooling, causing a vesicular look

Question 3

intrusive igneous rocks

Answer 3

formed deep within the earth
millions of years
big crystals
coarse grained

Question 4

extrusive igneous rocks

Answer 4

formed at or near the Earth’s surface
thousands of years
small crystals
fine grained

Question 5

texture

Answer 5

how coarse the surface of a rock is (due to how quickly/slowly it cooled)
coarse-grained, fine-grained, glassy, porphyritic

Question 6

how does porphyritic texture form

Answer 6

slow and then fast cooling

Question 7

felsic

Answer 7

composed of quartz/feldspar

Question 8

mafic

Answer 8

composed of magnesium/iron

Question 9

which is more dense, granite or basalt?

Answer 9

basalt

Question 10

you have 2 igneous rocks that have the same composition, but they are different rocks. How?

Answer 10

they cooled at different speeds

Question 11

describe rhyolite

Answer 11

intrusive
low density
felsic
cooled over millions of years
formed deep underground
small crystals
lighter color

Question 12

describe granite

Answer 12

intrusive
low density
felsic
cooled over millions of years
formed deep underground
large crystals
both light and dark colors mixed together

Question 13

describe basalt

Answer 13

extrusive
high density
mafic
cooled over thousands of years
formed at the surface
small crystals
dark grey/black

Question 14

obsidian

Answer 14

extrusive
low density
felsic
cooled over a short period of time
formed at the surface
glassy
black and shiny