The chemical formula of mineral Lazurite is indicated by (Na, Ca)8Al6Si6O24(S, SO4) or Sodium Calcium Aluminum Silicate Sulfur Sulfate. Lazurite is actually a Silicate mineral. Lazurite is also a member of both Sodalite and Feldspathoid Group of minerals. Lazurite is known to crystallize in the isometric system of crystal formation. In optical mineralogy, this isometric system comprises crystals having three axes, all of which are perpendicular to one another and all are found equal in lengths. The name of the mineral species Lazurite was derived from the Persian word Lazhward, which means blue. This is actually an allusion to its typical brilliant blue color as well as its resemblance to mineral Azurite. The first specimen of this species was discovered in 1890 at Lapis Lazuli Mine in Afghanistan. The name of this wonderful species Lazurite is most often confused with the other bright blue phosphate mineral called Lazulite. However, mineral Lazurite can be easily distinguished with Lazulite. Lazulite is known to exhibit a vitreous luster in reflected light of the polarizing microscopes for geologists and a good crystal habit. The other interesting species that has very similar color to Lazurite is the carbonate mineral azurite. Only difference is that azurite is usually associated with the green carbonate mineral called malachite. It is also notably found exhibiting reactions to acids.
Lazurite is commonly used as mineral specimen and also as ornamental stone. Specimens of mineral Lazurite are commonly found exhibiting nice and interesting microscope appearance under petrographic polarizing light microscopes. Mineral Lazurite is a popular mineral but it is generally an expensive mineral species. The rare and valuable ones are the well-formed crystals with deep blue color that is usually fascinatingly wonderful when viewed under petrographic polarizing light microscopes. Lazurite is most commonly found in massive form and usually combined with other minerals into a rock called lapis lazuli.
Lapis lazuli has been mined for almost centuries now from a locality still in use today at the remote mountain valley called Kokcha, Afghanistan. Lapis lazuli was first mined almost about 6000 years ago. The rock was then transported to Egypt and present day Iraq and later to Europe where it was used in jewelry and also for non-ornamental stone. Europeans also ground down the rock into an expensive powdered pigment used for paints called ultramarine. At present times, ultramarine is manufactured artificially. Although now it is not the only source of lapis, the source in Afghanistan still produces the finest quality material.
This Lapis Lazuli or lapis for short is mostly composed of Lazurite but also commonly contains pyrite and calcite and some other minerals. The name means blue rock and it is usually found having brilliant blue color with violet or greenish tints that can be seen clearly visible under petrographic polarizing microscopes. The rich blue color of the rock is due to the sulfur that is very inherent in the structure of the mineral Lazurite. Lapis also comprises crystals of pyrite wherein their brassy yellow color is very attractive as well as diagnostic in distinguishing lapis from its also blue cousin, sodalite rock, which is known to lack pyrite in its structure. Calcite usually produces white streaks in the lapis and too much calcite will actually lower the value of the stone.
Lazurite is most commonly found having brilliant blue color with violet or greenish tints that can be majestically exhibited under polarizing light microscopes. Lazurite is commonly found exhibiting dull to greasy luster in reflected light of petrographic polarizing microscope used in optical mineralogy. Lazurite is sometimes found showing poor cleavage in six directions. Lazurite is commonly found showing uneven fracture under polarizing microscopes for mineralogists. The specific gravity measure of the mineral is usually found 2.3grams per cubic centimeters to 2.4 grams per cubic centimeters, which is considered somewhat below average. The hardness measure of Lazurite when it is evaluated using the Mohs scale method is usually ranging from 5 to 5.5. Lazurite is commonly found leaving a bright blue streak when specimen sample is rubbed on a white porcelain streak plate.
Most Lazurite crystals are found translucent to opaque in appearance. The crystal habits of Lazurite as described in optical mineralogy usually include dodecahedral crystals, which have been found. Lazurite is usually found in massive form as rock forming mineral or lapis lazuli. Lazurite also exhibits low surface relief when viewed under several adjustments on the aperture diaphragm of the geological polarizing light microscope. Lazurite is an isotropic mineral species. In optical mineralogy, this means that Lazurite has no power to produce any illumination and it consequently appear totally dark when viewed at any angle between crossed nicols of the petrographic polarizing light microscopes. It has no birefringence because of its being isotropic. However, it can be also anomalously anisotropic when viewed under polarized microscope. The index of refraction that is commonly exhibited by Lazurite is usually 1.5. There is no specific data found on the toxicity and health dangers for mineral Lazurite. However, the specimens of this mineral species should be treated with great care and use of sensible precaution is advised upon handling them. Lazurite is a non-radioactive mineral species.
Lazurite is most commonly found associated with other interesting minerals like calcite, some pyroxenes and most diagnostic pyrite. The best field indicators of mineral Lazurite usually include the violet-blue color, pyrite association, specific gravity and locality. Lazurite is most often found forming as contact metamorphic mineral in limestones. Mineral Lazurite notably occurs at several localities including Kokcha River Valley in Afghanistan, near Lake Baikal in Russia, Ovalle in Cordillera, Chile as well as Mount Vesuvius in Italy, Cascade Canyon in San Bernardino Mountains and Ontario Peak in California. It can be also found in the Sawatch Mountains in Colorado, USA.
