, the following telluride and precious metal contact assemblages were observed: calaverite-native gold, calaverite-coloradoite, calaverite-coloradoite-native gold, calaverite-coloradoite-native gold-altaite, calaverite-petzite-native gold, calaverite-petzite, petzite-native gold, petzite-sylvanite-hessite

Fig. 6. Photomicrographs of representative sulfide and telluride mineralization at Sandaowanzi. (A) Intergrowth of petzite-calaverite with galena and sphalerite in stage II gray quartz veins (backscattered electron [BSE] image). (B) Altaite coexisting with petzite in stage III clear quartz veins

Fig. 10 Backscattered electron images (A–E) and reflected-light microphotograph (F) showing telluride assemblages. A. Intergrowth of petzite, hessite, tellurobismuthite, and altite in quartz. B. Irregular grains of tellurobismuthite in quartz. C. Oval-shaped calaverite in a microscopic void

Figure 4 Backscattered electron and electron microprobe elemental images of cross section of a partially reacted grain illustrating the range of products and textures of the calaverite-I, calaverite-II, petzite, hessite, and Au-Ag alloy (different grains from run A25). ( a ) Overview of a grain

), and Tuanjiegou ( i ). Panel f is a reflected images; others are secondary electron images. ( a ) Stützite coexisting with hessite in colloform quartz vein. ( b ) Sylvanite coexisting with petzite in colloform quartz vein. ( c ) Calaverite coexisting with petzite in colloform quartz vein. ( d ) Altaite

F ig . 7. (a) Zoned pyrite crystal in a quartz-albite-carbonate-pyrite vein, with an inner zone of dusty pyrite that contains inclusions of rutile (Rt) + native gold (Au) + calaverite (Clv), and an outer zone of pyrite. (b) Mineral association of native gold, calaverite, petzite (Ptz

Fig. 1. Micrographs of Au 2 Te grains and other minerals in reflected light. (A) Au 2 Te occurs as inclusions in petzite and hessite and enclosed in calaverite along the rim (sample sdwz4710b-1a). (B) Au 2 Te occurs as inclusions in petzite and hessite and enclosed in calaverite along the rim

of altaite, volynskite, petzite, galena, and rucklidgeite in pyrite. Micro-fractures are filled by rucklidgeite (arrow). Sample 1050-1a/1050 m. (c) Aggregate of gold, calaverite, petzite, and rucklidgeite in quartz. Gold and calaverite occur as rounded grains in petzite. Sample 1050-1b/1050 m. (d) Aggregate

, and volynskite) in bornite; c ,intergrowth of petzite and sylvanite with hessite and altaite in quartz; d – h, Sentyabr’skoe deposit: d, e , petzite, hessite, and native gold; f intergrowth of altaite and galena; g, h , intergrowth of hessite and pyrite; i , hessite inclusions in fahlore (Dvoinoe deposit

low interfacial angles of petzite against quartz and curvilinear grain boundaries between gold and petzite. Abbreviations: Hem = hematite, Hs = Hessite, Pet = petzite, Qz = quartz.

junction of three grain boundaries separating Q1 crystals. Reflected light. Sample EMTA2-1-1 from the Empire mine (north-south vein). c. Native gold intergrown with hessite, coloradoite, and petzite. The aggregate occurs along the grain boundary between two adjacent Q1 crystals. Reflected light. Sample

index [log(Q/K)] for the mineral petzite. ( e ) Mineral assemblages. ( f ) Mineral assemblages obtained by increasing the stability of petzite relative to the properties provided by Echmaeva and Osadchii (2009) (see text for details).

intergrown with pyrite, BSE image. E. Monazite containing gold particles, BSE image. F. Aggregate of gold and petzite in monazite, plane-polarized reflected light. G. Rutile and monazite coexisting with pyrite and sericite, plane-polarized transmitted light. H. Coexistence of rutile and monazite in quartz

Fig. 5. Reflected-light photomicrographs (A, C-E) and backscattered electron image (B) showing the petrographic features of native gold and telluride minerals. A. Abundant mineral inclusions in pyrite mainly consisting of native gold, calaverite, petzite, and chalcopyrite. B. Pyrrhotite

quartz with granoblastic texture. ( b ) Thin colloform texture with alternating bands of fine-grained jigsaw texture quartz and crystalline quartz. ( c–e ). Chalcedony, dark quartz, and crystalline quartz with a comb texture followed by tellurides. ( f ) Coarse-grained hessite, stützite, and petzite

Figure 1 ( a ) HAADF-STEM image showing intragranular microfracturing, porosity, and pore-attached NPs in pyrite. Abbreviations: Alt, altaite; Au, native gold; Cal, calaverite; Hs, hessite; Pz, petzite. Inset is selected area of electron diffraction obtained from circled area showing zone [1̄1̄2