Gemstones Tools

Lapis lazuli

Lapis lazuli oval cabochon
(la-pis'-la-zu-le)

13th c.; med. lat. lapis lazuli; pers. lazaward

Semi-transparent to transclucent stone that is usually rich azure blue and is essentially a complex silicate often with spangles of iron pyrites, mounted in jewelry
Color
Blue to violetish blue with specks of calcite and pyrite
Family
Lazurite
Chemical composition
(Na, Ca)8[Al6Si6O24]SO2 + calcite + pyrite + others
Crystal system
Aggregate
Hardness (Mohs scale)
5 - 6
Specific gravity
2,75 ±0,25 depends on the amount of pyrite
Refractive index
1,50
Birefringence
None
Optical character
None (aggregate)
Chanthaburi

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Jaipur

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