mineral
Turquoise
Hydrated phosphate of copper and aluminum, CuAl6(PO4)4(OH)8·4H2O
Hardness: 5-6 Mohs; Color: sky-blue to apple-green; Luster: waxy to sub-vitreous; Crystal system: Triclinic (usually massive); Specific gravity: 2.6-2.9
- Hardness
- 5-6 Mohs
- Color
- sky-blue to apple-green
- Luster
- waxy to sub-vitreous
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Physical properties
Hardness: 5-6 Mohs; Color: sky-blue to apple-green; Luster: waxy to sub-vitreous; Crystal system: Triclinic (usually massive); Specific gravity: 2.6-2.9
Formation & geological history
A secondary mineral formed by the percolation of acidic aqueous solutions during the weathering and oxidation of pre-existing minerals such as copper sulfides and feldspars in arid regions.
Uses & applications
Primary use is in jewelry as gemstones (cabochons or beads) and as decorative inlay material in traditional crafts.
Geological facts
Turquoise has been mined since at least 6000 BC in Ancient Egypt. It is one of the few minerals that has a color named after it. It is often stabilized with resin to improve durability.
Field identification & locations
Identified by its unique blue-green color and waxy appearance. Commonly found in Arizona, Nevada, Iran, and China. Collectors look for 'spiderweb' matrix patterns or solid 'Sleeping Beauty' blue colors.
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