Lead-tellurium oxysalts from Otto Mountain near Baker, California: III. Thorneite, Pb_6(Te_2^(6+)O_(10))(CO_3)Cl_2(H_2O), the first mineral with edge-sharing octahedral tellurate dimers
Abstract
Thorneite, Pb_6(Te_2^(6+)O_(10))(CO_3)Cl_2(H_2O), is a new tellurate from Otto Mountain near Baker, California, named in honor of Brent Thorne. The new mineral occurs on fracture surfaces and in small vugs in brecciated quartz veins. Thorneite is directly associated with acanthite, cerussite, gold, hessite, iodargyrite, khinite, wulfenite, and three other new tellurates: housleyite, markcooperite, and ottoite. Various other secondary minerals occur in the veins, including three other new secondary tellurium minerals: paratimroseite, telluroperite, and timroseite. Thorneite is monoclinic, space group C2/c, a = 21.305(1), b = 11.059(1), c = 7.564(1) Å, β = 101.112(4)°, V = 1748.8(4) Å^3, and Z = 4. Crystals are prismatic to bladed with elongation and striations parallel to c and typically occur in parallel and random aggregates. It is yellow and transparent, with pale yellow streak and adamantine luster. Mohs hardness is estimated at 2. The mineral is brittle, with an irregular to splintery fracture and good {100} cleavage. The calculated density is 6.828 g/cm^3. Thorneite is biaxial (+), with large 2V, but indices of refraction are too high to be measured. The optic orientation is Y = b, Z ^ a = 29° in obtuse β. No pleochroism was observed. Electron microprobe analysis provided PbO 73.90, ZnO 0.03, TeO_3 20.35, Cl 2.29, H_2O 1.28 (structure), CO_2 2.29 (structure), O≡Cl –0.52, total 99.62 wt%; the empirical formula (based on O+Cl = 16) is (Pb_(5.94)Zn_(0.01))(Te_(2.08)^(6+)O_(10))(C_(1.00)O_3)[Cl_(1.16)O_(0.34)(OH)_(0.50)](H_2O). The strongest powder X-ray diffraction lines are [d_(obs) in Å (hkl) I]: 10.43 (200) 35, 3.733 (5[overbar]11, 2[overbar]02, 002) 27, 3.595 (4[overbar]21) 33, 3.351 (112) 66, 3.224 (511, 131) 100, 3.093 (2[overbar]22, 3[overbar]31) 30, 2.900 (6[overbar]21) 44, 2.133 (821, 622, 223, 731, 242) 38. The crystal structure (R_1 = 0.028) contains edge-sharing octahedral tellurate dimers, [Te_2^(6+)O_(10)]^(8–) that bond to Pb atoms, which in turn are linked via bonds to Cl atoms, CO_3 triangles, and H_2O molecules.
Additional Information
© 2010 Mineralogical Society of America. Manuscript received January 28, 2010. Manuscript accepted May 5, 2010. Manuscript handled by G. Diego Gatta. We thank Associate Editor G. Diego Gatta, Technical Editor Ronald C. Petersen, referees Elena Sokolova and Filippo Vurro, and Stuart J. Mills for helpful comments on the manuscript. The Raman studies were conducted in the laboratory of George R. Rossman at the California Institute of Technology and with his assistance. The EMP analyses were supported by a grant to the California Institute of Technology from the Northern California Mineralogical Association. The remainder of this study was funded by the John Jago Trelawney Endowment to the Mineral Sciences Department of the Natural History Museum of Los Angeles County.Attached Files
Published - Kampf2010p11608Am_Mineral.pdf
Supplemental Material - Kampf_p1548_10_cif.txt
Supplemental Material - Kampf_p1548_10_structurefactor.doc
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Additional details
- Eprint ID
- 20577
- Resolver ID
- CaltechAUTHORS:20101028-090032988
- Northern California Mineralogical Association
- John Jago Trelawney Endowment
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2010-11-17Created from EPrint's datestamp field
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2021-11-09Created from EPrint's last_modified field