AbstractTaneyamalite, (Na,Ca)(Mn2+,Mg,Fe3+,Al)12 Si12(O,OH)44, is a Mn2+-dominant analogue of howieite, and has been found in the metamorphosed bedded manganese ore deposit of the lwaizawa mine, Saitama Prefecture, Japan. It is triclinic, P1 or P, a 10.198(1), b 9.820(1), c 9.485(1) Å, α 90° 30(1)′, β 70° 32(1)′, γ 108° 34(1)′, Z = 1. The strongest X-ray powder diffractions are: 9.29(80)010, 7.99(35)10, 4.62(50)020, 3.65(40)120, 3.273(100)30, 3.081(50)11, 2.790(35)31, 2.630(28)023, 2.216(35)014, 43. Taneyamalite occurs in association with minor bannisterite as small seams in a caryopilite mass or as a fissure mineral cutting a hematite-quartz mass. It is greenish grey-yellow, lustre vitreous. Streak light yellow. Cleavage {010}, perfect. H. (Mohs) about 5. Calculated sp. gr. 3.30 (on unit cell data and normalized empirical formula), 3.25 (after the Gladstone-Dale Law using the revised data of Mandarino, 1976). It is optically biaxial negative, 2Vα about 70°. The refractive indices: α = 1.646(2), β = 1.664(2), γ = 1.676(2). Extinction is nearly parallel, sign of elongation positive. Pleochroism distinct: α = β nearly colourless, γ pale yellow. Absorption: α ≈ β < γ.
Smectite appearance in the footwall of the Úrkút manganese ore deposit, Bakony Mts., Hungary