Image: <a rel="nofollow" class="external text" href="https://www.flickr.com/people/47445767@N05">James St. John</a> (CC BY 2.0)
cubiccommonSilicates
Chalcedony
SiO2
This specimen displays a botryoidal (grape-like) formation of light bluish-gray chalcedony with a characteristic waxy luster.
Chalcedony Physical Properties
Mohs Hardness
6.5Crystal System
cubicLuster
waxyStreak Color
whiteCleavage
NoneFracture
conchoidalSpecific Gravity
2.6Colors
white, gray, blue, brown, red, orange, greenTransparency
translucentType Locality
Round Mountain, Arizona, USAMineral Group
SilicatesUses
jewelry, ornamental objects, industrial abrasivesAssociated Minerals
quartz, opal, zeolites, calciteRarity
commonGeological Context
Chalcedony forms at low temperatures and pressures, often as a secondary mineral filling cavities in volcanic rocks (like basalt) or sedimentary rocks, or as a replacement mineral. It is commonly found in geodes, veins, and as concretions.
