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| Mineral Name: |
lazurite |
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| Gem Names: |
lapis or lapis lazuli |
| Chemistry: |
(Na,Ca)8(Al,Si)12O24(S, SO4)- FeS - CaCO3 |
| Class: |
silicate |
| Crystal Sys: |
isometric |
| Hardness: |
5 - 6 |
Specific Gravity: |
2.39 - 2.92 |
| Fracture: |
conchoidal |
Refractive Index: |
1.5 |
| Dispersion: |
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| Misc Prop: |
Lapis in the gem trade is not a pure mineral but rather a rock with lazurite, pyrite and calcite present. The more lazurite the better the quality, the pyrite can vary according to individual preference. The less calcite the better the quality as far as price is concerned.
In history lapis has been used as blue pigment in ultramarine blue. It was later replaced in oil paints by synthetics, but none have the longevity of the pigments created with lapis.
It has been used in Russia as a building material and wall panel covering. Today the best material comes from Afghanistan. Other areas include Chile, California and Colorado.
Lapis shows some porosity and should be protected from solvents and chemicals.
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| Color: |
In gemstones, color, is often the key to naming or describing the particular variety. Hence look for this information below in the various descriptions. Color, opacity, and homogeneity often determine the placement of value on any given stone, and are all optical properties of the particular stone. |
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