Onyx
Straight-banded chalcedony in black and white, the cameo stone.
- Family
- Chalcedony
- Formula
- SiO₂
- Mohs
- 6.5 to 7
- System
- Trigonal
Drag to turn
Science
True onyx is agate whose bands are flat and parallel rather than curved. Cutters exploit the layers to carve cameos, a pale figure standing on a dark ground. Sardonyx is the same structure in red-brown and white.
- Mineral
- Chalcedony (variety)
- Formula
- SiO₂
- Crystal system
- Trigonal
- Mohs hardness
- 6.5 to 7
- Specific gravity
- 2.58 to 2.64
- Refractive index
- 1.530 to 1.540
- Lustre
- Waxy to vitreous
- Colours
- Black, White
Composition
SiO₂. Made of Silicon, Oxygen.
Origin
- Brazil
- India
- Uruguay
- Madagascar
- United States
Filled dots are primary sources
Rarity
Common. Almost all solid black onyx is grey chalcedony dyed with sugar and sulphuric acid.
- 1 Abundant
- 2 Common
- 3 Uncommon
- 4 Rare
- 5 Exceptional
Hardness
Onyx sits at 6.5 to 7 on the Mohs scale. It will scratch glass and holds a polish in daily wear.
Energy
Associations from crystal-healing tradition, recorded here as folklore. They are not medical claims.
Chakras
- Root
Element
- Earth
Zodiac
- Leo
- Capricorn
Planets
- Saturn
Properties
- Protection
- Self-control
- Strength
- Discipline
Lore
Onyx is Greek for fingernail: Cupid is said to have clipped Venus's nails while she slept and the Fates turned the parings to stone so no part of a goddess would perish.
Roman soldiers carried sardonyx engraved with Mars; in medieval Europe the black stone got a reputation for nightmares that modern practice has reversed into protection.
- DyeThe sugar-acid method dates to Roman Idar-Oberstein and is standard.
- Marble onyxBanded calcite sold as 'onyx' is a different, softer stone.