Metamorphosed sulphides

Pyrrhotite, sphalerite, chalcopyrite and galena. Unknown Provenance

Pyrrhotite crystals (brown) show bireflectance and reflection pleochroism (light brown to darker brown, centre). They are equidimensional and have triple junctions which suggest they have recrystallized. Inclusion-free sphalerite (light grey, bottom) is intergrown and encloses a grain of galena (white, bottom right) and chalcopyrite (top centre).

Polished block, plane polarized light, x80, air

Sphalerite, galena and chalcopyrite. Unknown Provenance

Sphalerite (light grey), galena (white, top left) and chalcopyrite (yellow, centre top) are complexly intergrown. Galena has penetrated along cleavages in the silicates (centre, right centre). Dark grey areas are amphibole (top right), quartz and other silicates.

Polished block, plane polarized light, x80, air

Sphalerite, pyrrhotite and galena. Unknown Provenance

Pyrrhotite (brown, bottom) is intergrown with sphalerite (light grey, left) and galena (white, centre). A central silicate crystal has curved cleavage planes along which galena, pyrrhotite and sphalerite have penetrated. Dark grey areas are silicates.

Polished block, plane polarized light. x80, air

Pyrrhotite, sphalerite, chalcopyrite and galena. Unknown Provenance

Pyrrhotite shows bireflectance and reflection pleochroism from brown to light brown-yellow (bottom left). The differences in polishing between pitted and well polished pyrrhotite grains reflect different crystal orientations of the pyrrhotite. Sphalerite (light grey, centre right), chalcopyrite (yellow, centre) and galena (white, top centre) form incomplete margins about pyrrhotite. Dark grey phases are tabular metamorphic silicates. The uniform grain size of the pyrrhotite shows it to have recrystallized.

Polished block, plane polarized light, x80, air

Sphalerite, pyrrhotite, chalcopyrite and galena. Unknown Provenance

Sphalerite (light grey) is intergrown with pyrrhotite (brown) which shows reflection pleochroism and bireflectance (bottom left) and the effects of orientation on polishing characteristics (centre and bottom left). Anhedral chalcopyrite (yellow, top centre) and galena (white, top centre) commonly surround pyrrhotite. Dark grey areas are quartz and metamorphic silicates.

Polished block, plane polarized light, x80, air

Chalcopyrite, pyrrhotite, magnetite, sphalerite and pyrite. Sweden

Chalcopyrite (yellow) is intergrown with pyrrhotite (light brown, left) and minor sphalerite (grey, bottom left). Within the silicate-rich central areas, euhedral magnetite (light grey, higher reflectance than sphalerite, centre) carries pyrrhotite inclusions. A single euhedral crystal of pyrite (white, centre left) is present.

Polished block. plane polarized light, x80, air