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Lazurite Specimen 2

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Original price $210
Current price $200

A bunch of Lazurite crystals with pyrite; perfect termination and bright color.

Weight: 112 grams

Origin: Badakhshan, Afghanistan

Color: Blue


Looks like a triangle.

 

LAZURITE

Lazurite is a tectosilicate mineral with sulfate, sulfur and chloride with formula (Na,Ca)8[(S,Cl,SO4,OH)2|(Al6Si6O24)]. It is a feldspathoid and a member of the sodalite group. Lazurite crystallizes in the isometric system although well‐formed crystals are rare. It is usually massive and forms the bulk of the gemstone lapis lazuli. Lazurite is a deep‐blue to greenish‐blue. The colour is due to the presence of S−3 anions. It has a Mohs hardness of 5.0 to 5.5 and a specific gravity of 2.4. It is translucent with a refractive index of 1.50. It commonly contains or is associated with grains of pyrite. Lazurite is a product of contact metamorphism of limestone and is typically associated with calcite, pyrite, diopside, humite, forsterite, hauyne and muscovite.

GENERAL

Category

Tectosilicate

Formula

(Na,Ca)8[(S,Cl,SO4,OH)2|(Al6Si6O24)]

Strunz classification

9.FB.10

Crystal system

Isometric

Crystal class

Hextetrahedral (43m)
H-M symbol: (4 3m)

Space group

P43n

Unit cell

a = 9.09 Å; Z = 2

Identification

Color

Deep blue, azure, violet-blue, greenish blue

Crystal habit

Crystals occur as dodecahedra, or rarely cubes; granular, disseminated, or massive

Cleavage

Imperfect on {110}

Fracture

Uneven

Tenacity

Brittle

Mohs scale hardness

5–5.5

Luster

Vitreous

Diaphaneity

Translucent to opaque

Specific gravity

2.38–2.45

Optical properties

Isotropic; anomalously anisotropic

Refractive index

1.502–1.522

Fusibility

3.5

Solubility

Soluble in HCl