ON OSARIZAWAITE, A NEW MINERAL OF THE ALUNITE GROUP. FROM THE OSARIZAWA MINE, JAPAN

Abstract

Osarizawaite, a new mineral. from the Osarizawa mine occurs in the oxidized zone of lead-zinc-copper veins as earthy and friable masses, associated with other secondary minerals of lead or copper. The chemical formula of osarizawaite has been determined as Pb (Cu_0.98 Zn_0.02) (Al_0.81 Fe_{0.1 ??} )₂ (SO₄)₂ (OH)₆. Its physical and optical properties are: greenish-yellow in colour; specific gravity=3.89-4.02, 4.20 (calc.); mean index of refraction=1.735-1.757, birefringence strong. The unit cell dimensions for both the hexagonal cell and the corresponding rhombohedral cell are: α₀=7.05Å., c₀=17.23Å., Z=3; α_rh=7.04Å., α=60°06′, Z=1. The data obtained demonstrate that the mineral is a new species being the aluminum analogue of beaverite and belongs to the alunite group. A new mineral name, osarizawaite, is proposed for the mineral which belongs to the alunite group and whose ideal chemical formula is PbCuAl₂(SO₄)₂(OH)₆ where Cu and Al may be partially replaced by Zn and Fe respectively.