Pyrite and native gold. Dolgellau Gold Belt, Wales, Britain
Pyrite (light pink-blue, top left) contains abundant inclusions of native gold (yellow, high reflectance) some in a symplectite like intergrowth (bottom left). The gold is replacing pyrite. Quartz is black or shows strong internal reflections (bottom right). The gold is 780 fine. Specimen number BM077R44. British Museum Collection. The perceived anomalous colour of the pyrite is due to the strong colour and high reflectance of native gold.
Polished block, plane polarized light, x 160, oil