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a mineral, a phosphate of magnesium, iron, and aluminum; its chemical composition is (Mg, Fe2+) A12 [P04]2(OH)2. Lazulite crystallizes in the monoclinic system, forming dark blue acicular crystals of dipyramidal form. It sometimes occurs in granular aggregates in association with quartz and other minerals. Its hardness is 5–6 on Mohs’ scale, and its density is 3,100 kg/M3. Lazulite is encountered in the contact zones of pegmatites, in quartz veins, in quartzite and metamorphic rocks, and in association with corundum, rutile, kyanite, and other minerals.