Formula: Ca₂Cu[B(OH)₄]₂(OH)₄

Species: Borates

Colour: Blue-violet

Lustre: Vitreous

Hardness: 4

Hardness: 1.5-2

Specific Gravity: 2.51

Crystal System: Triclinic

Transparency: transparent

Calcium Copper Hydroborate Hydroxide. It comes from only one location in the planet; the Fuka mine, near Bicchu-cho, Takahashi, Okayama Prefecture, Chugoku Region, Honshu Island, Japan. Henmilite occurs in small cavities in pentahydroborite veins at the marble quarry, where contact-metamorphosed limestone is being mined. The first example of a borate containing both Ca and Cu. Copper borates are rare in nature. Bandylite is the first naturally occurring copper borate, henmilite being the second