crystals of lazurite : Sar-e-Sang, Koksha Valley, Badakshan, Afghanistan — Photo: Parent Géry · CC BY-SA 3.0
Lazurite
Also known as: Lapis lazuli component.
The sulfur-bearing feldspathoid of the sodalite group that gives lapis lazuli its deep blue.
Intro adapted from Wikipedia (CC BY-SA).
Lazurite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na₇Ca(Al₆Si₆O₂₄)(SO₄)(S₃)¹⁻·H₂O.
It crystallizes in the cubic crystal system (space group P-43n). It is a member of the Cancrinite-sodalite, Sodalite structural group.
Key properties: Mohs hardness 5–5.5; specific gravity 2.38–2.45; typically blue; Bright blue streak; Vitreous luster; refractive index 1.512.
IMA symbol Lzr, IMA status: approved, named in 1891.
A contact metamorphic mineral in limestones.
It is found associated with Calcite, pyrite, diopside, humite, forsterite, haÄuyne, muscovite.
The name refers to its color resemblance to azurite, named from the Persian lazhward, for blue.
Collections: Gemstones, Collector Favorites.