Agate
Agate is a kind of quartz and it is a mineral. Agate can come in many different kinds and colors. Agate deposits are primarily found in large rocks such as boulders. agates take 50 million years to form. It is characterized by colored band patterns inside various rocks. Often, agates are also accompanied by Amethyst deposits inside.[1]
| Agate | |
|---|---|
 Moss agate pebble, 2.5 cm (1 inch) long | |
| General | |
| Category | Quartz variety |
| Formula (repeating unit) | Silica, SiO2 |
| Identification | |
| Color | White to grey, light blue, orange to red, black. |
| Crystal habit | Cryptocrystalline silica |
| Crystal system | Rhombohedral Microcrystalline |
| Cleavage | None |
| Fracture | Conchoidal with very sharp edges. |
| Mohs scale hardness | 7 |
| Luster | Waxy |
| Streak | White |
| Specific gravity | 2.58-2.64 |
| Refractive index | 1.530-1.540 |
| Birefringence | up to +0.004 (B-G) |
| Pleochroism | Absent |
References
- Streeter, Edwin W. (2014-07-07). Semi-Precious Stones - A Historical Article on Agate, Amber, Amethyst and Many Other Varieties of Gemstones. Read Books Ltd. ISBN 978-1-4733-9436-0.
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