mineral
Chrysoprase (green chalcedony), likely rough fragment
Chalcedony, microcrystalline quartz (SiO₂), colored green primarily by nickel-bearing inclusions
AI-generated identification · may be incorrectTypically translucent pale apple-green with a waxy to vitreous luster; hardness about 6.5–7 Mohs, cryptocrystalline structure, no cleavage, and conchoidal fracture. The pictured piece may also contain tan host rock or weathering material.
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Physical properties
Typically translucent pale apple-green with a waxy to vitreous luster; hardness about 6.5–7 Mohs, cryptocrystalline structure, no cleavage, and conchoidal fracture. The pictured piece may also contain tan host rock or weathering material.
Formation & geological history
Forms when nickel-rich groundwater alters silica in serpentinized ultramafic rocks, commonly as veins or cavities. It is generally Cenozoic or younger, though host-rock ages vary widely.
Uses & applications
Used as a semiprecious gemstone for cabochons, beads, carvings, and ornamental objects; rough fragments have modest collecting value.
Geological facts
Chrysoprase is the rarest commercially important green chalcedony and was historically used in jewelry associated with ancient Greece and Rome.
Field identification & locations
Identify by its even translucent green color, quartz hardness, waxy surface, and absence of cleavage; common sources include Australia, Brazil, Poland, Tanzania, and the United States. A scratch test should be performed only on an inconspicuous surface.
