Describing Igneous Rocks Flashcards
1
Q
3 ways to describe igneous rocks
A
Texture
Mineralogy
Geochemistry
2
Q
Textures
A
Degree of crystalinity
Crystal size
Crystal shape
Mineral relations
3
Q
Texture: degree of crystalinity
A
Holocrystaline: 100% crystalline
Holohyaline: 100% glass
Hypocrystaline: crystals in a glass matrix
4
Q
Texture: crystal size
A
Aphanitic: fine grained (cannot see with naked eye)
Phaneritic: coarse grained (all about the same size)
Porphoritic:2 distinct crystal sizes(usually crystals in matrix)
Seriate: contains a range of crystal sizes,
.
5
Q
Ground mass
A
Also known as matrix
6
Q
Crystal shape
A
Euhedral: well developed crystals
Anhedral‐poorly developed crystals
Subhedral: some crystal faces are observed
Hypodiomorphic:mix of all of the above
7
Q
Exolution
A
When 1 mineral decides into 2 minerals
