Class : Carbonates, nitrates, borates
    Subclass : Borates
    Crystal system : Orthorhombic
    Chemistry : Mg₃B₇O₁₃Cl
    Rarity : Uncommon

Boracite is a mineral that crystallizes in the cubic system above 265°C ; below it becomes orthorhombic while maintaining cubic forms. Magnesium can be partially replaced by iron (ericaite variety) or manganese (chambersite variety). It owes its name to the boron it contains. Boracite is present in beds in ancient evaporite deposits, especially in the German Permian, associated with anhydrite, gypsum, halite (Lüneburg), kainite and carnallite (Stassfurt) and in saliferous diapirs. American (Louisiana and Mississippi). It comes from the light metamorphism of hydrated borates. The crystals are generally millimetric and display cubic forms or derived from the cube : dodecahedron, cubo-octahedron, tetrahedron. Boracite is sometimes massive, saccharoid, resembling a fine-grained white marble, but much harder. It is usually colorless or tending towards gray, yellow or green. Boracite is highly piezoelectric. It is an exceptionally boron ore and has sometimes been cut for jewelery. It is a mineral little known to collectors.

Boracite is not present in the French underground.

A boracite twinning on (111) exists but is very rare.

No fake inventories for this mineral species. Some crystals could be glued on matrix...