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Semiprecious stone valued for its deep-blue colour caused by the presence of the mineral lazurite, which is the source of the pigment ultramarine. Lapis lazuli is not a single mineral but an intergrowth lazurite with calcite, pyroxene, and commonly small grains of pyrite. The most important mines are in Afghanistan and Chile. Much of what is sold as lapis is an artificially dyed jasper from Germany that shows colourless specks of clear, crystallized quartz and never the goldlike flecks of pyrite that are characteristic of lapis lazuli.
This entry comes from Encyclopædia Britannica Concise. For the full entry on lapis lazuli, visit Britannica.com.