Honeaite, a new gold-thallium-telluride from the Eastern Goldfields, Yilgarn Craton, Western Australia

Abstract

Honeaite, ideal formula Au3TlTe2, is a new mineral from the late Archaean Karonie gold deposit, Eastern Goldfields province, Western Australia. Honeaite is found with native gold, tellurobismuthite, petzite, hessite, calaverite, melonite, mattagamite, frohbergite, altaite, pyrrhotite and molybdenite. These minerals are concentrated in microvughs and microfractures mainly within areas of prehnite alteration of amphibolite. The mineralisation appears to have been deposited under greenschist-facies conditions at lower temperatures than most gold deposits in the Eastern Goldfields. Single-crystal X-ray studies identified the structure of honeaite as orthorhombic, space group Pbcm , with a = 8.9671 (4) A, b = 8.8758(4) A, c = 7.8419(5) A, giving V = 624.14(6) A3 with Z = 4. The strongest reflections of the calculated powder X-ray diffraction pattern are [ d in A (Irel)( hkl) ]: 2.938(100)(022), 2.905 (39,8)(322, 411), 2.989 (31)(300), 2.833 (23)(310), 1.853 (17)(332). Electron-microprobe analysis (EDS mode) gave (wt%) Au 56.33, Tl 19.68, Te 24.30, total 100.31, leading to an empirical formula (based on 2 Te apfu ) of Au3.00Tl 1.01Te 2.00. Honeaite is black with a metallic lustre and no observed cleavage. The calculated density is 11.18 g/cm3. In reflected plane-polarized light it is slightly bluish grey. Between crossed polars it is weakly anisotropic with dark brown to dark blue rotation tints. Reflectance values in air and in oil are given. Honeaite is named after the late Russell M. Honea (1929–2002).