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Lazurite (Lapis Lazuli)
Current inventory:  0 gems
 

Lapis Lazuli

Chemistry:  Na6Ca2Al6Si6O24[(SO4),S,Cl,(OH)]2

Discovered in 1890;   IMA status: Valid (pre-IMA; Grandfathered).
The nam Lazurite is from the Persian word lazhward meaning blue.

 

Classification

   

   

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/J.11-40

 

8 : Silicates
J : Tectosilicates (network) without anions unfamiliar to the tetraheders
11 : Sodalite group, Tsaregorodtsevite - Wadalite series

 

 

Crystal Data

   

   

Crystallography:

Isometric - Hextetrahedral

Crystal Habit:

In dodecahedra, or more rarely cubes, up to 5 cm; granular, disseminated, or massive.

Twinning:

None

 

 

Physical Properties

   

 

Cleavage:

[110] Imperfect

Fracture:

Irregular, Uneven

Tenacity:

Brittle

Moh's Hardness:

5.5

Density:

2.38 - 2.42 (g/cm3)

Luminescence:

Fluorescent

Radioactivity:

Not Radioactive

 

 

Optical Properties

   

   

Color:

Blue, Azure blue, Violet blue, Greenish blue

Transparency:

Translucent, Opaque

Luster:

Vitreous to Dull

Refractive Index:

1.50 - 1.522  Isotropic

Birefringence:

0.00 (Isotropic)

Dispersion:

0.014 (low)

Pleochroism:

Distinct; purplish-red - orange-red

Anisotropism:

Anomalous

 

 

Occurances

   

   

Geological Setting:

A contact metamorphic mineral in limestones.

Type Locality:

Lapis-lazuli Mine, Sar-e-Sang, Badakhshan (Badakshan; Badahsan) Province, Afghanistan

Year Discovered:

1890

View mineral photos:

Lazurite/Lapis Lazuli Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 


Lazurite (Lapis Lazuli)
is one of the members of the Feldspathoid group of minerals that includes Cancrinite, HaŁyne, Lazurite, Leucite, Nepheline and Sodalite. Minerals with chemistries that are close to those of the alkalai Feldspars, but are poor in silica (SiO2) content, are called Feldspathoids. Lazurite is also a member of the Sodalite group of minerals that includes Hackmanite, HaŁyne and Tugtupite. Lazurite could be considered a Sulphur rich form of HaŁyne. Lazurite crystals are rarely found however. It is more commonly found combined with other minerals as a rock called Lapis Lazuli, or just Lapis. Lazurite and Lapis are two separate things; Lazurite is a mineral and Lapis Lazuli is a rock composed of many different minerals; but we are grouping them together on this page since they are so closely related. Lapis contains mostly massive forms of Lazurite combined with HaŁyne, Sodalite, Nosean, (all members of the Sodalite group of minerals) and white Calcite, Pyrite, and other minerals. The Calcite and Pyrite give Lapis a very attractive look and the presence of Pyrite distinguises Lapis from its blue cousin - Sodalite rock, which lacks Pyrite.

The name Lazurite is often confused with another blue mineral, the phosphate mineral Lazulite. Although the names are similar, their crystal habit is very different. Lazurite is very rarely found as distinct crystals and Luzulite has good crystal habit and vitreous luster. The carbonate mineral Azurite has a very similar color to Lazurite but is associated with the green carbonate mineral Malachite and reacts to acids.

Lapis Lazuli has been mined for centuries from a source still in use today in the remote mountain valley of Kokcha, Afghanistan. Although there are other sources of Lapis worldwide, Afghanistan still produces the finest quality material.
 

  
Lazurite/Lapis Lazuli gems for sale:

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