Igneous rocks Flashcards
1
Q
Igneous rocks mineral composition
A
mafic- dark minerals like olivine and Pyroxene
Felsic- light minerals like Quartz and Feldspar
Intermediate- some Mafic, Felsic
2
Q
Igneous Rocks crystalline
A
Aphanitic (can’t see), Phaneritic ( can) Pegmatitic ( very large grains; slow cooling)
3
Q
Igneous rocks glass
A
obsidian-black glass, Magma into water so very rapid cooling.
b) Pumice- white, many holes so floats.
4
Q
Porphyritic- 2 grain sizes, slow cooling
A
a) ash 1/7 diameter
b) cinder 1/7-1
c) Lapilli 1-3
4) Bolcanic Bomb - >3
