Rock & Mineral Encyclopedia

Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.

Chrysocolla

A vivid blue-green hydrated copper silicate, soft on its own but prized as a gem when hardened by intergrown quartz or chalcedony.

A rare deep-blue copper silicate mineral, often fibrous or massive, named for the Shattuck Mine in Arizona and prized by collectors.

A rare, intensely blue chalcedony colored by copper-rich chrysocolla, prized as the most valuable of the blue chalcedonies.

A vivid copper-bearing Mexican stone of red cuprite and green chrysocolla that evokes a desert sunset.

Natural emerald crystals still embedded in their host rock, prized as mineral specimens that show how the gem grew in place.

Aquamarine crystals still attached to their natural host rock, prized as mineral specimens showing beryl in its original pocket setting.

A contact-metasomatic calc-silicate rock, essentially a skarn, formed where intrusions react with carbonate rocks and often host ore.

An exceptionally coarse-grained igneous rock, often granitic, famous for hosting large crystals and many gemstones.

Opal in which precious play-of-color is intimately dispersed through the pores of its host rock rather than forming a solid seam.

A rare ultrapotassic, magnesium-rich volcanic rock from deep in the mantle, famous as the diamond host at Argyle in Australia.

Agate that forms in flat cracks or veins of host rock rather than rounded nodules, producing straight, parallel banding.

Precious opal that forms in thin veins within brown ironstone boulders, cut with the host rock left as a natural dark backing.