Lindgrenite from the Sansei mine, Nara Prefecture, Japan

Abstract

Lindgrenite, Cu₃(MoO₄)₂(OH)₂, was found in a dump at the Sansei mine, Nara Prefecture, Japan. It occurred as aggregates of thin platy crystals up to 3 mm wide in veinlets in quartz, and as a mono-mineral or in association with limonite, chrysocolla and malachite. It was yellowish green with a greasy luster in hand specimen. The Vickers microhardness was 351 kg mm⁻² (25 g load) and the density was 4.24 g cm⁻³. The empirical formula of the mineral was Cu_2.98Mo_2.01O_8.05(OH)_1.95 on the basis of O = 10. The unit cell parameters were a = 5.620(1), b = 14.043(2), c = 5.041(1) Å, and β = 98.49(1)°. It is likely that lindgrenite at the Sansei mine was formed as a secondary mineral in solutions dissolved from bornite and molybdenite.