Lazulite, also known as Azure spar, is a blue mineral that ranges from transparent to semi-opaque. It is composed of magnesium, iron, and aluminum phosphates, with the chemical formula (Mg,Fe2+)Al2(PO4)2(OH)2. Lazulite is part of a solid solution series that includes the darker, iron-rich mineral scorzalite.
This mineral crystallizes in the monoclinic system, exhibiting crystal forms that are typically steep bipyramidal or wedge-shaped. Lazulite has a Mohs hardness rating between 5.5 and 6.0, along with a specific gravity of 3.0 to 3.1. It is characterized by its infusibility and insolubility.
