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Appendix 4
Rock Identification Charts
Table 4: Field classification of igneous rocks
|
Category |
Principal
minerals |
%
silica |
% dark
minerals |
phaneritic |
aphanitic |
glassy |
|
Felsic |
>10% quartz
>2/3 K-feldspar |
72 |
10 |
Granite |
Rhyolite |
Obsidian
|
|
<10% quartz
> 2/3 K-feldspar |
59 |
15 |
Syenite |
Trachyte |
|
1/3 - 2/3 feldspars, ~ 50/50 K-feldspar &
plagioclase |
55 |
20 |
Monzonite |
Latite |
|
Intermediate |
>10% quartz
>10% K-feldspar
>2/3 Na-feldspar |
66 |
20 |
Granodiorite |
Dacite |
|
<10% quartz
<10% K-feldspar
>2/3 Na-feldspar |
57 |
25 |
Diorite |
Andesite |
|
|
Mafic |
<10% quartz >2/3 Ca-feldspar |
48 |
50 |
Gabbro Anorthosite |
Basalt |
Tachylite |
|
Ultramafic |
0% quartz
mafic minerals only |
41 |
95 |
Pyroxenite Peridotite
Dunite |
|
|
|
|
Table 5: Field classification of metamorphic rocks
|
REGIONAL METAMORPHISM |
|
Original
rock |
Metamorphic rank
Low
High |
|
chlorite |
biotite |
almandite |
staurolite |
sillimanite |
|
Metamorphic rock |
|
Shale |
Slate |
Biotite phyllite |
Biotite-garnet phyllite |
Biotite-garnet-staurolite schist |
Sillimanite schist or gneiss |
|
Argillaceous sandstone |
Micaceous sandstone |
Quartz-mica schist |
Quartz-mica-garnet schist or gneiss |
|
Quartz sandstone |
Quartzite |
|
Limestone,
Dolomite |
Limestone
Dolomite |
Marble |
|
Basalt |
Greenschist:
chlorite-epidote-albite schists |
Albite-epidote amphibolite |
Amphibolite |
|
Granite |
Granite |
Granite gneiss or Migmatite |
|
Rhyolite |
Rhyolite |
Biotite schist or Gneiss |
|
CONTACT METAMORPHISM |
|
Sandstone |
Quartzite |
|
Limestone, Dolomite |
Marble |
Serpentinite, Soapstone |
|
Argillaceous sandstone |
Hornfels |
Granulite |
|
Coal |
Anthracite |
Graphite |
|
Basic igneous rocks |
Serpentinite, Soapstone |
|
|
Table 6: Field
classification of sedimentary rocks
|
|
|
CLASTIC: made of particles of older rocks
and their alteration products |
|
|
Texture |
Grain size |
Name |
|
|
Detrital
Clastic |
Granule or larger, >2mm |
Conglomerate (rounded)
Breccia (angular grains) |
|
|
Sand, 0.05 – 2mm diam |
Sandstone |
|
|
Silt, 0.05 – 0.005mm |
Siltstone, loess |
|
|
Clay, < 0.005 mm |
Mudstone, shale |
|
|
NON-CLASTIC: made of minerals deposited
from solution |
|
|
Origin |
Texture |
Composition |
Name |
|
|
Inorganic & organic |
Crystalline & clastic |
Calcite, CaCO3 |
Limestones, chalk, travertine, tufa |
|
|
Inorganic |
Crystalline |
Dolomite,
CaMg(CO3)2 |
Dolomite |
|
|
Inorganic |
Crystalline |
Halite, NaCl |
Rock salt |
|
|
Inorganic |
Crystalline |
Gypsum, CaSO4.2H2O;
anhydrite, CaSO4 |
Gypsum, anhydrite |
|
|
Inorganic & organic |
Crystalline & clastic |
Silica, SiO2 |
Chert, flint, novaculite, diatomite |
|
|
Organic |
Clastic & crystalline |
Carbonized plant remains |
Lignite, coal, anthracite |
|
|
Organic |
Crystalline |
Iron oxides & hydroxides |
Banded iron ores |
|
|