metamorphic
Lapis lazuli bead bracelet
Lazurite-bearing calcite–pyrite rock; lazurite formula (Na,Ca)₈(AlSiO₄)₆(S,SO)₂
AI-generated identification · may be incorrectTypically deep royal blue with white calcite and occasional metallic-gold pyrite; lazurite has Mohs hardness about 5–5.5, vitreous to dull luster, and an imperfect granular structure without prominent cleavage. The beads are polished and shaped, so surface appearance is enhanced by processing.
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Physical properties
Typically deep royal blue with white calcite and occasional metallic-gold pyrite; lazurite has Mohs hardness about 5–5.5, vitreous to dull luster, and an imperfect granular structure without prominent cleavage. The beads are polished and shaped, so surface appearance is enhanced by processing.
Formation & geological history
Formed by contact metamorphism of carbonate rocks, commonly marble, during intrusion of silica- and sulfur-rich magma; major deposits are geologically Precambrian, especially Afghanistan’s Hindu Kush. The pictured material is human-processed into tumbled beads.
Uses & applications
Used for beads, carvings, ornamental objects, and historically as the source of ultramarine pigment; commercial jewelry value depends strongly on saturated blue color and low white calcite content.
Geological facts
True lapis lazuli is a rock rather than a single mineral. Bright blue lazurite, white calcite veining, and tiny brassy pyrite grains are diagnostic; uniform dyed substitutes and sodalite are common imitations.
Field identification & locations
Commonly found in Afghanistan, Chile, Russia, Pakistan, and California. In the field, inspect unpolished surfaces for blue lazurite mixed with calcite and pyrite; streak testing is preferable to scratching finished beads.
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