Tondiite, Cu3Mg(OH)(6)Cl-2, the Mg-analogue of herbertsmithite

作者：Malcherek T^*; Bindi L; Dini M; Ghiara M R; Molina Donoso A; Nestola F; Rossi M; Schlueter J

来源：Mineralogical Magazine, 2014, 78(3): 583-590.

DOI：10.1180/minmag.2014.078.3.08

• herbertsmithite
• new mineral
• basic copper chloride
• Vesuvius
• Caleta Vitor
• haydeeite

Tondiite, with the simplified formula Cu3Mg(OH)(6)Cl-2, occurs as a rare supergene mineral in a phonolitic tephrite from the type locality, Vesuvius volcano, Italy, as well as associated with haydeeite in the Santo Domingo Mine, Arica Province, Chile. It is emerald green to bright green in colour and occurs in irregularly shaped crystals, often with stepped faces. Its calculated density is 3.503 g cm(-3). Tondiite crystallizes with the herbertsmithite structure type, space group R (3) over barm. Lattice parameters are a = 6.8377(7) angstrom and c = 14.088(2) angstrom for the holotype material. The c parameter may vary with Mg/Cu ratio and the presence of impurity atoms. The five strongest lines in the calculated powder diffraction pattern are [d in angstrom (I)(hkil)]: 5.459(88)(10 (1) over bar1), 3.419(22)(11 (2) over bar0), 2.764(100)(11 (2) over bar3), 2.266(54)(02 (2) over bar4), 1.706(26)(22 (4) over bar0). Several tondiite crystals have been examined by single-crystal X-ray diffraction and by electron microprobe analysis. The observed Mg content ranges between 0.6 and 0.7 atoms per formula unit. The structural role of Mg is discussed.

• 出版日期2014-6