Science Fair Project Encyclopedia
Onyx
- This article is about the mineral. See Onyx (disambiguation) for other meanings
Onyx is a banded variety of chalcedony, a cryptocrystalline form of quartz. The colours of its bands are white and black. It is usually cut as a cabochon, or into beads, and is also used for intaglios and cameos. Some onyx is natural but much is produced by the staining of agate.
| Chemical composition and name | SiO2 - Silicon dioxide |
| Hardness (Mohs scale) | 7 |
| Specific gravity | 2.65 - 2.66 |
| Refractive index (R.I.) | 1.543 - 1.552 to 1.545 - 1.554 |
| Birefringence | 0.009 |
| Optic sign | Positive |
| Optical character | Uniaxial |
See also
10-26-2009 08:16:03
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details