trigonalcommonSilicates
Chalcedony
SiO2
This image shows a polished specimen of banded chalcedony, commonly known as agate, displaying concentric layers of white, grey, reddish-brown, and brown with a waxy luster and botryoidal habit.
Chalcedony Physical Properties
Mohs Hardness
6.5Crystal System
trigonalLuster
waxyStreak Color
whiteCleavage
noneFracture
conchoidalSpecific Gravity
2.6Colors
white, grey, brown, reddish-brown, blue, orangeTransparency
translucentType Locality
Widespread globally, notable occurrences in Brazil, Uruguay, India, USAMineral Group
SilicatesUses
jewelry, ornamental objects, carving materialAssociated Minerals
quartz, calcite, zeolitesRarity
commonGeological Context
Chalcedony forms from low-temperature aqueous solutions, often filling cavities in volcanic rocks (like basalt) or as a precipitate in sedimentary environments, crystallizing as microscopic fibers of quartz.
