Calciborite, CaB<sub>2</sub>O<sub>4</sub>, is a rare calcium borate mineral.
It was first described in 1955 in the Novofrolovskoye copperâÂÂboron deposit, near Krasnoturinsk, Turinsk district, Northern Ural Mountains, Russia. It occurs in a skarn deposit formed in limestone adjacent to a quartz diorite intrusive. It occurs associated with: sibirskite (another rare calcium borate mineral), calcite, dolomite, garnet, magnetite and pyroxene. It has also been reported from the Fuka mine of Okayama Prefecture, Japan.