Johillerite

IMA formula: NaCuMgMg₂(AsO₄)₃

Crystallography: Monoclinic. I2/a. a = 6.7520(14) Å, b = 12.739(3) Å, c = 11.068(2) Å, β = 100.37(3)°. Z = 4.

Specimen #215. Johillerite. Arsenatnaya fumarole, Second scoria cone, Northern Breakthrough (North Breach), Great Fissure eruption (Main Fracture), Tolbachik Volcanic field, Milkovsky District, Kamchatka Krai, Russia. FOV 6.2 mm.