Quartzite (Sioux Quartzite, Paleoproterozoic, 1.65 to 1.70 Ga; Sioux Falls area, city of Sioux Falls, Transcontinental Arch, southeastern South Dakota, USA) by James St. John, on Flickr
Quartzite Information
| Data | Value |
|---|---|
| Name | Quartzite |
| Is a Variety of | Quartz |
| Varieties | Aventurine |
| Colors | Usually white or grey, sometimes pink, red, brown. |
| Fracture | Conchoidal to uneven, Granular in aggregates |
| Hardness | 7 |
| Cleavage | None or indistinct |
| Crystallography | Aggregate |
| Birefringence | None |
| Luster | Greasy to waxy. |
| Specific Gravity | 2.64-2.69 |
| Transparency | Opaque. |
| Phenomena | Aventurescence. |
Comments
A rock made up of tightly packed quartz grains, formed at high temperature and pressure, due to metamorphism. Sometimes it contains small crystals that reflect light, and this material is called aventurine. Usually the included crystals are green, chrome-rich mica called fuchsite. Other micas that may form aventurine include gray varieties or brown types (from Chile). The density is usually 2.64-2.69. Occurrence: Spain; USSR; India; Chile.
Stone Sizes
Quartzite and milky quartz are massive varieties available in large pieces.
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