Image: <a rel="nofollow" class="external text" href="https://www.flickr.com/people/47445767@N05">James St. John</a> (CC BY 2.0)
cubiccommonCarbonates
Onyx
CaCO3
The image displays whitish, banded stalactites, which are cave formations composed of travertine, a form of calcite commonly known as onyx marble or Mexican onyx.
Onyx Physical Properties
Mohs Hardness
3Crystal System
cubicLuster
vitreousStreak Color
WhiteCleavage
Perfect rhombohedral on {1011}Fracture
Conchoidal to unevenSpecific Gravity
2.71Colors
white, cream, brown, yellow, green, pinkTransparency
Translucent to opaqueType Locality
Crystal Onyx Cave, near Cave City, Kentucky, USAMineral Group
CarbonatesUses
decorative stone, carvings, jewelry, architectural materialAssociated Minerals
Rarity
commonGeological Context
These formations occur in a Tertiary-Quaternary cave within limestones and dolostones of the Ste. Genevieve Limestone in Kentucky, USA. They are formed by the slow deposition of calcite from supersaturated mineral-rich water.
