Gold and Electrum (Reflected Light)

Gold (Au) and electrum (Au-Ag alloy) optical properties using a reflected-light polarizing microscope (adapted from Spry & Gedlinske, 1987):

System: Cubic

Reflectance: Strong

Colour: Bright or golden yellow; electrum is slightly lighter and less yellow

VHN and polishing hardness: 53 - 58 / soft

Pleochroism: Nonpleochroic

Anisotropism: Isotropic but incomplete extinction; a greenish shade is often observed

Internal reflections: Not present

Twinning: (111) common

Commonly associated minerals: Arsenopyrite, berthierite, calaverite, chalcopyrite, cinnabar, cobaltite, niccolite, pitchblende, pyrite, sperrylite, stibnite, tellurides, ullmanite, uraninite

Sample from the EOSC424 reflected light sample collection at UBC