Turquoise
Turquoise is a phosphate mineral prized by collectors for its exceptional color range, with known Chinese sources.
About Turquoise
Turquoise is a phosphate mineral in the turquoise group and has the chemical formula CuAl6(PO4)4(OH)8 · 4H2O. It crystallizes in the triclinic system and is one of the most visually varied minerals in the collector market. Its combination of structural character and global distribution make it a recognized species in both systematic and aesthetic collections.
Identification & care
Crystals commonly develop as massive, nodular, botryoidal; veins, crusts; tiny crystals very rare. Its color range is broad, including bright blue, sky-blue, pale green, blue-green, turquoise-blue, apple-green, and green-gray. The luster is sub-vitreous, resinous, waxy, dull, earthy, the streak is pale greenish blue to white, and specimens are typically transparent, translucent, opaque. The cleavage is perfect on {001}, good on {010}. The fracture is conchoidal to uneven, which aids identification.
Collector context
How it forms
Turquoise forms in secondary mineral in oxidized zones of copper-rich arid-region deposits; forms by weathering of feldspar-bearing rocks with copper-rich fluids and phosphate ions; requires arid conditions. It is commonly found in association with chalcopyrite, malachite, azurite, limonite, kaolin, quartz.
Classic Chinese localities
Turquoise is widely represented across Chinese provinces, including Yunnan, Hubei, Henan, Shaanxi.
Why collectors care
Collectors pursue Turquoise for its patterns, color depth, and polish response rather than for pattern character. Good material has a surface that polishes cleanly, a visual character that holds up in direct light, and enough size to anchor a display on its own. Chinese sources, where present, supply much of the material currently cut and sold as decorative pieces.
What affects value
Value in Turquoise is assessed, in typical order of weight, against: (1) source locality; (2) size; (3) pattern and visual character; (4) color depth and distribution; (5) polish response and surface finish; (6) piece integrity (absence of major cracks or chips). Uniqueness of pattern and verified source region add significantly to decorative pieces.
Naming history
The name Turquoise has a specific etymological and historical context — see Mindat's reference entry for provenance details. We have retained naming data at the record level; published prose is paraphrased from factual fields rather than copied from source.