Geology 1110

Qualities that define minerals

natural
inorganic
solid
specific chemical composition
characteristic crystalline structure

Extrusive igneous rock groups

Rhyolite (quartz and feldspar phenocrysts)
Andesite (plagioclase and amphibole/pyroxene phenocrysts)
Basalt (plagioclase and pyroxene/olivine phenocrysts)

Intrusive igneous rock groups

Granite (feldspar and quartz)
Diorite
Gabbro

Rock Cycle

-igneous rock forms as magma cools
-igneous rock is weathered, becomes unconsolidated
-unconsolidated material becomes consolidated or sedimentary rock
-sedimentary rock is either uplifted and weathered or heated and pressurized to metamorpic
-metamorphic

Mineral Identification

streaking
cleavage planes
hardness
density
crystal form and growth

Mineral Groups

Silicate
Sulfides
Oxides
Halides
Carbonates
Sulfates
Phosphates
Native Elements (crystal structures of single element)

Silicate Minerals

Orthosilicates-single tetrahedra
Disilicates-2 tetrahedra
Inosilicates-chains of tetrahedra
Phyllosilicates-sheets of tetrahedra
Tectosilicates-3D tetrahedra network

Coarse grained igneous rock

Phanerite (G. "visible") >= 2mm at largest dimension

Fine grained igneous rock

Aphanite (G. "invisible") <2mm at largest dimension

Mostly course grained igneous rock

Porphyry

Isolated large grains in fine grained matrix

Phenocrysts

Pyroclastic rock groups (non-mineral)

bombs >64mm
lapilli 2mm-64mm
ash <2mm

Tephra rock groups (sedimentary pyroclasts)

Agglomerate-coarse grain
Tuff-fine grain
Welded tuff-glassy cemented ash particles

Plutons (intrusive igneous rock formations)

Minor
-Dikes (vertical)
-Sills (horizontal)
-Laccoliths (mushroom shaped because viscous)
-Volcanic pipe
Major
-Batholiths (large irregular shaped bodies intruding in other rock)
-Stoping-expanding magma fractures chamber walls and causes chunks to fall
-

Common mineral groups

Olivine (Mg,Fe)2SiO4, Garnet (orthosilicate)
Pyroxene (single chains),
Amphibole (double chains)
Micas (sheets)

Crust composition by weight

O (45.2%)
Si (27.2%)
Al (8%)
Fe (5.8%)
Ca (5.06%)
Mg (2.77%)
Na (2.32%)
K (1.68%)
Ti (0.86%)
(the rest are less than 2%)

Varves

Pair of layers in lake sediment defined by year