ON CLINOCLASITE FROM KITABIRA, YAMAGUCHI PREFECTURE, JAPAN

Abstract

Clinoclasite, a basic arsenate of copper, from the Kitabira mine, Yamaguchi Prefecture has been described. It is found usually as massive aggregates of small flakes with limonite or iron-rich clay. The crystal is platy parallel to (001), and has monoclinic symmetry. The cell dimensions are a0=12.48Å, b0=6.48Å, c0=7.27Å and β=99°02′ (morphologically). Forms: c(001), a(100), m(110), n(810), v( ?? 121) and s( ?? 552). Colour: greenish blue or deep blue. Streak: bluish green. Translucent. Hardness 2.5-3. Cleavage (001) perfect. Sp. gravity 4.33 (9°C). Opt. properties: α=1.739, β=1.87, γ ?? 1.9, 2V ?? (-) 50°:v〉r strong; a ?? Z (c∧X ?? 10°); Pleochroic. Chemical analysis follows, As2O5 29.66, Al2O3 0.63, Fe2O3 0.32, CaO 0.05, CuO 62.42, H2O(+) 7.55, H2O(-) 0.36, total 100.99%. The X-ray powder diagram of this specimen agrees well with the data given by Palache and Berry.