Tumbled turquoise (likely matrix-bearing)

Typically Mohs hardness 5–6, opaque blue-green to green, waxy-to-dull luster, cryptocrystalline structure, and no visible cleavage; the specimen shows pale blue-green color with dark brown/black matrix or pits. Exact identification is uncertain from the image alone because similar materials include variscite, dyed howlite, and chrysocolla.

Forms as a secondary mineral in arid, oxidized copper deposits when phosphate-rich groundwater alters aluminum-bearing rock. Deposits are generally geologically young relative to their host rocks, commonly Cenozoic to older hydrothermal systems.

Used as a cabochon, bead, carving, and collector specimen; historically valued in jewelry and ornamentation. It is relatively soft and porous, so it is often stabilized with resin.

Turquoise’s color reflects copper, while iron tends to produce greener hues and matrix records the surrounding host rock. Many commercial pieces are stabilized, reconstituted, dyed, or imitated.

Common sources include Iran, the southwestern United States, Mexico, China, Egypt, and Chile. Field clues are blue-green color, low hardness, opaque waxy appearance, and often brown host-matrix veining; testing should be non-destructive.