What is "hydroboracite"

n. (context mineral English) A hydrated borate mineral with the chemical formula CaMgB₆O₈(OH)₆·3(H₂O).

Hydroboracite is a hydrated borate mineral (hence the name) of calcium and magnesium, whose chemical composition is CaMgBO(OH)·3HO. It was discovered in 1834 in Atyrau Province, Kazakhstan. Hydroboracite is a minor borate ore mineral.