WUPATKIITE FROM THE CAMERON URANIUM DISTRICT, ARIZONA, A NEW MEMBER OF THE HALOTRICHITE GROUP

Wupatkiite (Co,Mg,Ni)Al-2(SO4)(4) . 22H(2)O is a new member of the hal otrichite group. It occurs 8 miles ESE of Gray Mountain, Arizona, near the prehistoric pueblo dwelling Wupatki. It occurs as cross-fibre vei nlets with fibres up to 8mm long. Colour: empire rose (RHS48C), streak white, H. = 1 1/2. G = 1.92, D(calc) = 1.87g/cm(3). Nonpleochroic wit h alpha = 1.477, gamma = 1.484, Z fibre axis = 12 degrees. Wet chemist ry gave MgO 1.63, CaO 0.10, MnO 0.17, FeO 0.15, NiO 0.52, CuO 0.12, Co O 3.41, Al2O3 11.30, S03 35.97, H,O 42.26 (total 95.63%); rem. = montm orillonite and quartz. Parameters refined from the powder pattern are close to those of halotrichite. Wupatkiite is monoclinic P2(1)/c with a = 6.189 Angstrom, b = 24.23 Angstrom, c = 21.20 Angstrom, beta = 100 .33 degrees. Strongest lines are 4.790, 100 (024); 4.295, 27 (140); 3. 945, 26 (025); 3.768, 33 (062); 3.494, 92 (124, 063).