What is Lazurite?
Lazurite is a deep blue feldspathoid mineral and the principal blue mineral associated with lapis lazuli, valued for intense colour, geological provenance and its complex cage-bearing aluminosilicate framework.
Mineralogy and crystal structure
Reference formula: (Na,Ca)8(AlSiO4)6(SO4,S,Cl)2. Lazurite is a cubic feldspathoid tectosilicate of the cancrinite-sodalite family. Lazurite has a variable composition in which sodium and calcium occupy framework cavities and sulfate, sulfide, chloride and related anions vary between samples. The simplified formula is therefore a compositional guide rather than a claim that every lazurite has identical occupancy. The selected COD 9011355 record is a cubic lazurite model; polytypes and modulated varieties also occur. The reference record uses cubic symmetry. Typical hardness is 5–5.5 on the Mohs scale and specific gravity is approximately 2.4–2.5.
Colour, lustre and habit
Typical colours include deep blue, azure blue, blue-violet, greenish-blue. The usual massive, granular, crystalline habit and vitreous, pearly, dull lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Lazurite forms in or is associated with contact- and regional-metamorphic calc-silicate rocks, altered limestones and lapis lazuli-bearing marble. Important documented localities include Afghanistan, Russia, Chile, Tajikistan, Myanmar and Canada.
The blue mineral inside lapis lazuli
Lazurite is where a saturated royal-blue colour meets serious mineralogy. The best specimens preserve a clear lapis-lazuli provenance, natural colour zoning and a mineral assemblage that explains the blue rather than treating the colour as a standalone sales claim.
Collecting and care
Protect the relatively soft surface from scratches, acids and harsh cleaners. Avoid prolonged soaking and retain locality information because lapis lazuli is a rock and may contain calcite, pyrite and other minerals alongside lazurite.
