Adanite, a new lead-tellurite-sulfate mineral from the North Star mine, Tintic, Utah, and Tombstone, Arizona, USA

Adanite, Pb₂(Te^4þO₃)(SO₄), is a new oxidation-zone mineral from the North Star mine, Tintic district, Juab County, Utah, and from Tombstone, Cochise County, Arizona, USA. The characterization of the species is based principally on North-Star holotype material. Crystals are beige wedge-shaped blades, up to about 1 mm in length, in cockscomb intergrowths. The mineral is transparent with adamantine luster, white streak, Mohs hardness 2½, brittle tenacity, conchoidal fracture, and no cleavage. The calculated density is 6.385 g/cm³. Adanite is biaxial (–), with a = 1.90(1), b = 2.04(calc), c = 2.08(calc), 2V(meas) = 54(1)8. The Raman spectrum is consistent with the presence of tellurite and sulfate groups and the absence of OH and H₂O. Electron-microprobe analyses gave the empirical formula Pb_1.89Sb³⁺_0.02Te⁴⁺_0.98S⁶⁺_1.04Cl_0.02O_6.98. The mineral is monoclinic, space group P2₁/n, with a = 7.3830(3), b = 10.7545(5), c = 9.3517(7) Å, b = 111.500(8)8, V = 690.86(7) ų, and Z = 4. The four strongest X-ray powder diffraction lines are [d_obs Å(I)(hkl)]: 6.744(47)101, 3.454(80)211; 122; 200, 3.301(100)202; 031; 210, and 3.048(73)ð112; 221; 113. The structure (R₁ = 0.022 for 1906 I . 2rI reflections) contains Te⁴⁺O₃ pyramids that are joined by short (strong) Pb–O bonds to form sheets. Interlayer SO₄ groups link the sheets via long Pb–O and Te–O bonds.