Last modified 01 / 11
| 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 |
| Particle Size | Composition | Comments | Rock Name | |||
| Clastic |
Coarse Grains > 2 mm |
Any rock type (quartz, chert, or quartzite most common) | Rounded clasts | Conglomerate | ||
| Angular clasts | Breccia | |||||
|
Fine Grains 1/16 to 2 mm Can be seen w/ naked eye |
Quartz with minor accessory minerals | White, tan, brown; sandpapery feel | Quartz Sandstone | S A N D S T O N E |
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| Quartz, with at least 25% potassium feldspar (orthoclase) | Often reddish because of potassium feldspar; sandpapery feel | Arkosic Sandstone | ||||
| Rock fragments, mica, clay, quartz | "Dirty" looking, dark colored; sandpapery feel | Graywacke | ||||
|
Very Fine Grains <1/16 mm Cannot be seen w/ naked eye |
Quartz and clay minerals | Gritty, 1/16-1/256 mm; some grains may be seen with hand lens | Siltstone | M U D S T O N E |
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| Clay
sized particles; < 1/256 mm |
Non-foliated; "clay the size" |
Claystone | ||||
| Foliated; "clay the mineral" |
Shale | |||||
| Biological | Varies, generally very fine grained | Calcite (CaCO3) fizzes with dilute HCI |
Abundant fossils | Fossiliferous Limestone | ||
| Powdery; shells of microscopic plants and/or animals | Chalk | |||||
| Coarse to very fine grained | Calcite (CaCO3) fizzes rapidly with dilute HCI |
Fossils & fossil fragments; loosely cemented | Coquina | |||
| Varies, generally fine grained | Carbonaceous Material | Plant remains |
Brown, soft, porous | Peat | ||
| Brown | Lignite | |||||
| Black, sooty, blocky | Bituminous Coal | |||||
| Bio-Chemical |
Generally very fine grained | Calcite (CaCO3) | Non-friable; fizzes with dilute HCI | Limestone | ||
| Dolomite (Ca,Mg) (CO3)2 |
Non-friable; fizzes with dilute HCI only when powdered | Dolostone | ||||
| Chalcedony (Si02) | Light colored, h = 7 | Chert | ||||
| Dark colored, h = 7 | Flint | |||||
| Chemical | Generally very fine grained | Calcite (CaCO3) | Fizzes with dilute HCl |
Medium to coarse grained | Crystalline Limestone | |
| Ooids (tiny spheres) | Oolitic Limestone | |||||
| Banded | Travertine | |||||
| Halite (NaCI) | Evaporite, tastes salty | Rock Salt | ||||
| Gypsum (CaSO4 2H20) | Evaporite, hardness of 2 | Gypsum | ||||
| 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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