Onyx
2 in the gallery
Onyx is a form of chalcedony consisting of alternating light and dark parallel bands. The material typically shows a waxy to dull luster and a solid to slightly translucent appearance, with colors ranging from cream to black or deep brown in the darker bands. It often occurs as banded stalactitic or massive forms that can be polished to reveal crisp belt-like stripes. Brazilian material is among the most widely collected and admired, with classic banding patterns that form eye-catching scenes when cut as slabs or carved into cabochons.
- Formula
- SiO2
- Rarity
- Common
- Stability
- Stable
- Collector interest
- High Interest
- Classification notes
- Silicate mineral; Quartz group (SiO2)
Key characteristics
- Crystal system
- trigonal
- Mohs hardness
- 6.5–7
- Specific gravity
- 2.55–2.7
- Luster
- vitreous, waxy, dull
- Transparency
- translucent, opaque
- Color
- black, white, gray, brown, red, orange
- Streak
- white
- Cleavage
- none
- Fracture
- conchoidal, subconchoidal, uneven
- Crystal habit
- massive, granular
- Gem mineral
- Classic / historic
Where Onyx is found
Top localities
- Minas Gerais1 specimen
About Onyx
Collectors value onyx for its historical use in decorative carvings and its versatile aesthetic in display pieces. The striking contrast of bands makes each specimen unique, and care for onyx involves standard mineral handling plus gentle polishing to preserve the delicate banding. While onyx can occur in a range of environments, it is the banded chalcedony varieties that attract attention in cabinet displays and with craftspeople who favor bold, graphic patterns.