1 Revision 2 2 3 Lead–tellurium oxysalts from Otto Mountain near Baker, California: XI. Eckhardite, 2+ 6+ 4 (Ca,Pb)Cu Te O5(H2O), a new mineral with HCP stair-step layers. 5 6 Anthony R. Kampf1,*, Stuart J. Mills2, Robert M. Housley3, George R. Rossman3, Joseph Marty4, 7 and Brent Thorne5 8 9 1Mineral Sciences Department, Natural History Museum of Los Angeles County, 10 900 Exposition Blvd., Los Angeles, CA 90007, U.S.A. 11 2Geosciences, Museum Victoria, GPO Box 666, Melbourne 3001, Victoria, Australia 12 3Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, 13 CA 91125, U.S.A. 14 45199 E. Silver Oak Road, Salt Lake City, UT 84108, U.S.A. 15 53898 S. Newport Circle, Bountiful, UT 84010, U.S.A. 16 *e-mail:
[email protected] 17 18 ABSTRACT 2+ 6+ 19 Eckhardite, (Ca,Pb)Cu Te O5(H2O), is a new tellurate mineral from Otto Mountain near Baker, 20 California, U.S.A. It occurs in vugs in quartz in association with Br-rich chlorargyrite, gold, 21 housleyite, khinite, markcooperite, and ottoite. It is interpreted as having formed from the partial 22 oxidation of primary sulfides and tellurides during or following brecciation of quartz veins. 23 Eckhardite is monoclinic, space group P21/n, with unit cell dimensions a = 8.1606(8), b = 24 5.3076(6), c = 11.4412(15) Å, β = 101.549(7)°, V = 485.52(10) Å3, and Z = 4. It forms as needles 25 or blades up to about 150 x 15 x 5 µm in size, typically in radial or sub-radial aggregates, but also 26 as isolated needles.