Location:

Gold-platinum placer. Kalimantan, Indonesia

The samples are a gold-rich concentrate from a river placer.

Major Minerals:

Gold-silver alloys, zircon, ilmenite, magnetite, cassiterite, pyrite

Minor and trace Minerals:

Include platinum-iron alloys, iridosmine, osmiridium, chromite, cinnabar, marcasite, rutile.

Textures:

The gold fineness is related to its colour and reflectance. Gold enrichment rims have lower reflectance and are deeper yellow than the silver-rich cores. Copper-bearing gold-silver alloys are pinker than gold-silver alloys

References:

Stumpfl and Clark, 1965; Stumpfl, 1974; Bowles et al., 1984