Igneous Rocks Flashcards
1
Q
What should be ignored when observing igneous grain size?
A
Phenocrysts
2
Q
What texture has no grains?
A
Glassy
3
Q
What does felsic/silicic mean?
A
Quartz and feldspar (silica rich)
4
Q
What does mafic rocks mean?
A
Contain magnesium and iron (ferric- ferromagnesium)
5
Q
What is the appearance of mafic rocks?
A
Darker
6
Q
What is the appearance of silicic rocks?
A
Lighter
7
Q
Obsidian
A
- Exception to the rule
- Looks black but is felsic
- Clear in thin section
8
Q
What is magma?
A
Mixture of molten rock, solid materials (crystals) and volatiles (dissolved gases)
9
Q
What does a minor intrusion mean?
A
Hypabyssal depth including dykes and sill
10
Q
What does a major intrusion mean?
A
Plutonic depth include batholiths
11
Q
A
