Niccolite, native silver, maucherite, acanthite and safflorite. Great Bear Lake, Canada
Native silver (white, centre) forms a Marienberg cross within radiating niccolite (pink-brown, centre) that shows faint reflection pleochroism (light to dark pink-brown). Other silver crystals are rhombic (centre right) and may have pseudomorphed dolomite. Niccolite has thin rims of maucherite (blue-grey), which shows very faint zoning (bottom centre). The outermost zone is safflorite but the two arsenides are difficult to distinguish at this magnification. Acanthite (dark grey, right centre) has replaced native silver. Yellow areas (top right) within silver are due to tarnishing of the silver. Black areas are calcite. Scratches within native silver do not pass into the nickel arsenides and demonstrate the low hardness of silver.
Polished block, plane polarized light, x 160, oil