Lapis lazuli
Image: James Petts from London, England (CC BY-SA 2.0)
Mineral NameLapis lazuli
Chemical Formula(Na,Ca)8[(S,Cl,SO4,OH)2|(Al6Si6O24)] (primary mineral lazurite)
Mohs Hardness5
Streak Colorlight blue
Cleavagenone (as a rock)
Fractureuneven to conchoidal
Specific Gravity2.75
Colorsdeep blue, azure blue, violet-blue
Transparencyopaque
Type LocalityBadakhshan, Afghanistan
Mineral GroupMetamorphic rock (composed of silicates, carbonates, sulfides)
Usesjewelry, ornamental, pigment, carving
Associated Mineralslazurite, calcite, pyrite, sodalite, hauyne
Rarityuncommon
Description
A dark blue, irregularly shaped rock fragment with a rough, uneven surface, displaying variations in blue intensity and some darker, possibly greyish-black, areas.
Geological Context
Lapis lazuli forms in metamorphosed limestones or marbles through contact metamorphism, typically associated with igneous intrusions in high-temperature environments.
