6.5 - 7.0 on the Mohs scale.

Worldwide. Chalcedony, a micro-crystalline member of the quartz family consists of a number of stones, namely agate, dendritic agate, fire agate, heliotrope (bloodstone), plasma, chrysoprase, prase, fossilized (petrified) wood, jasper, cornelian (carnelian), moss agate, onyx, sardonyx, and sard.

Opaque to translucent, colors can vary quite wildly depending on the chalcedony variety.

Refer to specific chalcedony pages.

More information on gemstone enhancements.

Chalcedony is a member of the Quartz gemstone family.