Igneous Rocks Flashcards
0
Q
Pyro clastic
A
Fragments of rocks erupted from volcanos
1
Q
Where are igneous rocks found?
A
Pluton (large intrusion below the earths surface)
Nearer the surface in cracks or fractures
Dyke or sill minor intrusion
2
Q
Define nucleation centre
A
“Any small disturbance in the melt, such as specks of impurity or slight movements, may be sufficient for the first tiny crystals to start to form.”
3
Q
Gabbro describe
A
Coarse grained >2
Plutonic rock of crystalline texture
4
Q
Define dolerite
A
Medium grained 0.25–2
Dark containing plagioclase pyroxene and olivine. Typically formed in dykes and sills
5
Q
Basalt describe
A
Fine grained <0.25
Consists of largely pyroxene olivine and plagioclase, dark
