Sphalerite, pyrite and jamesonite. Ireland
500µm
Concentrically banded pyrite (yellow, centre) is intergrown with sphalerite (light grey, bottom left). Acicular crystals of jamesonite (blue-grey, centre top) are found within calcite (dark grey) which shows bireflectance (top right).
Polished block, plane polarized light, x 40, air
