updated 02 / 17
| Metallic | H<2.5 | H 2.5 to 3.5 | H 3.5 to 5.5 | H >5.5 | Glossary | Tests | Index |
| Rock Summary | Igneous | Sedimentary | Metamorphic |
| TEXTURE | PARTICLE SIZE | COMPOSITION | COMMENTS | ROCK NAME | |
Foliated |
Foliated | Fine grained, minerals not visible | Minerals with basal cleavage: commonly mica, graphite, etc. | Dense; thin pieces will pass the "tink" test | Slate |
| Minerals with basal cleavage: commonly mica, graphite, etc. | Satiny luster; very shiny and reflective in sunlight | Phyllite | |||
| Foliated
or Lineated |
Medium to coarse grained; grain size will generally increase with metamorphic grade | Muscovite, biotite, chlorite, talc, garnet, kyanite, staurolite, feldspar, quartz, tourmaline, and many others | Name is preceded by diagnostic minerals: such as quartz schist, mica schist, quartz mica schist, kyanite biotite hornblende schist, etc. | Schist | |
| Color Banded | Feldspar, quartz, mica, ferromagnesian minerals | Color banding due to alternation of light (felsic) and dark (mafic) minerals | Gneiss | ||
| Mixed metamorphic and igneous rock | Feldspar, quartz, mica, ferromagnesian minerals | Alternating layers of felsic igneous rock and mafic gneiss; the last metamorphic grade prior to complete melting | Migmatite | ||
| Non-foliated | Non-oriented grains | Fine to coarse grained, minerals visible | Calcite (CaCO3) | Hardness of 3; fizzes with dilute HCI | Marble |
| Dolomite (Ca,Mg) (CO3)2 |
Fizzes with dilute HCI only when powdered | Dolomitic Marble | |||
| Quartz (SiO2) | H = 7; breaks through grains (as opposed to sandstone that breaks around grains) | Quartzite | |||
| Amphibole; commonly hornblende | Generally black; prismatic crystals with 2 directions of cleavage at 60° / 120° | Amphibolite | |||
| Anything that could be a conglomerate (or breccia) | Breaks through clasts as well as around them; clasts may be flattened or stretched | Meta- conglomerate (or -breccia) |
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| Fine grained, minerals not visible | Microcrystalline texture; may exhibit fibrous asbestos forms | Dense; dull to glossy; various shades of green to black; often with slickensides | Serpentinite | ||
| Carbonaceous material | Black; shiny; conchoidal fracture | Anthracite Coal |
| Metallic | H<2.5 | H 2.5 to 3.5 | H 3.5 to 5.5 | H >5.5 | Glossary | Tests | Index |
| Rock Summary | Igneous | Sedimentary | Metamorphic |
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