Euhedral crystals of borcarite were found in vugs or fissures of crystal aggregates of nifontovite or pentahydroborite, which occur as irregularly shaped bodies in the crystalline limestone near the gehlenite-spurrite skarns at the Fuka mine, Okayama Prefecture, Japan. Interfacial angles of the reference faces of borcarite crystals were measured for each zone using a one-circle goniometer. The crystal basically comprises the {110}, {230}, {201}, {124} and {201} faces, but some crystals also have the {100}, {102}, {101}, {130}, {140}, {180}, {311} and {511} faces. Almost all the mineral is thin plate crystals along the zone [010]. The cleavage is perfect on {100}. Striation can be observed in the direction of [001]. This is the first description of a crystalline form of borcarite.