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Turquoise

Phosphate Minerals

Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula CuAl6(PO4)4(OH)8.4H2O. It is rare and valuable in finer grades and has been prized as a gemstone for millennia because of its hue. The word dates to the 16th century and derives from the Old French turquois, meaning Turkish, because the mineral was first brought to Europe through the Ottoman Empire from mines in the historical Khorasan province of Iran. In this atlas it is the mineral species that the gemstone turquoise records.

Facts
Kind
Mineral 1
Chemical Formula
CuAl6(PO4)4(OH)8.4H2O 1
Hardness (Mohs)
5.5 1
Commonly cited range is 5 to 6 on the Mohs scale; 5.5, the midpoint, is used here.
Classification
Crystal System
Triclinic 1
Classification
Phosphate Mineral 1
Use
Gemstone 1
Connections

Classified As

Entity-backed identity for the material classification this material already carries as an enum fact, pointing at the class subcategory of the same name. The enum fact itself stays on the entity unchanged.

Crystallizes In System

Entity-backed identity for the crystal system this mineral already carries as an enum fact, phase 3 bucket conversion (docs\design_entity_backed_browse_buckets_20260928.md, w-bucketconv-divmore2-0929). The original fact stays on the entry unchanged.

In Discipline

In the Other Atlases
Sources
1. Turquoise (Wikipedia)
Wikimedia Foundation
  • Turquoise, lead paragraph
    is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium
  • Turquoise, article text
    It is rare and valuable in finer grades and has been prized as a gemstone for millennia due to its hue.
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