Onyx
Layer stone with the combination of a black base and a white upper layer, also called true onyx or Arabic onyx. Onyx is also a name sometimes used for unicolored Chalcedony (e.g., black onyx).
The name onyx has its origin in the Greek language and means "fingernail", probably because of its weak transparency.
The name onyx has its origin in the Greek language and means "fingernail", probably because of its weak transparency.
| General Information | |
|---|---|
| A variety or type of: | Agate, which is a variety of Chalcedony, which is a variety of Quartz |
| Onyx Treatments | |
| Black chalcedony ("onyx") is assumed to be dyed - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 7 | |
| Physical Properties of Onyx | |
| Mohs Hardness | 6 to 6.5, Gemmological Tables (2004) More from other references |
| Specific Gravity | 2.55 to 2.70, Blue Chart Gem Identification (2010) |
| Optical Properties of Onyx | |
| Refractive Index | 1.530 to 1.543, Blue Chart Gem Identification (2010) |
| Optical Character | Uniaxial/+, Gemmological Tables (2004) |
| Colour | |
| Colour (General) | Black, Gemmological Tables (2004) More from other references |
| Transparency | Translucent,Opaque, Gemmological Tables (2004) More from other references |
| Crystallography of Onyx | |
| Crystal System | Trigonal, Gemmological Tables (2004) |
| Further Information | |
| Mineral information: | Onyx information at mindat.org |