Contents
Mineral Composition group and Chemical Formula
Sarah Sorden March 2002
Physical properties
| Streak | White |
| Luster | glassy, vitreous (cryptocrystalline forms are usually waxy to dull but can be vitreous) |
| Hardness | 7 |
| Color | , pink, brown, yellow, purple, white ( Cryptocrystallinevarieties can be multicolored. ) |
| Density | 2.65 |
| Hcl | no |
| Cleavage | none |
| Fracture | conchoidal |
| Special Properties | Piezoelectric |
| Name | Description |
|---|---|
| Crystalline Quartz | |
| Amethyst | Clear purple or bluish violet; transparent |
| Cat's eye | Gray, brown, or green streak; opalescent |
| Milky quartz | White; nearly opaque |
| Rock crystal | Colorless; transparent |
| Rose quartz | Pink; transparent to translucent |
| Sapphire quartz | Indigo blue; rare |
| Smoky quartz (Cairngorm) | Yellow, brown, or black; cloudy |
| Yellow quartz (Citrine) | Yellow or golden brown; transparent |
| Cryptocrystalline Quartz | |
| Agate | White, red, brown, or blue; banded |
| Carnelian | Red or flesh red; translucent |
| Chalcedony | Milky or grayish; transparent to translucent |
| Chert | White, yellow, gray, or brown; brittle |
| Chrysoprase | Apple-green; translucent |
| Flint | Gray, brown, or nearly black; opaque |
| Jasper | Red, yellow, brown, or green; opaque |
| Onyx | Straight and parallel bands of different colors |
| Plasma | Various shades of green; faintly translucent |
| Prase | Dull green; translucent |
| Sardonyx | Colored bands of red, brown, or white |