native sulfur

Iridescent Native Silver

Something about the structure in which the metal precipitated from the element charged fluid that carried and concentrated the silver from its source rock is acting like a diffraction grating, much like the regular arrangements of silica spheres in opals. The spacing in the structure is similar in size to the wavelengths of visible light, and the light diffracts into its component wavelengths. In this specimen from Norway (4.1x4.4x3.5cm) the bright shiny silver shimmers across a spectrum of red, green and blue, while dull grey silver sulphides such as acanthite and polybasite sit next to it atop the matrix.


Image credit: Exceptional Minerals