Mica Sheet — Cleavage Plane Interference Colours
30.16 د.ك
A freshly cleaved muscovite mica sheet photographed in polarised light — the variable thickness of the cleavage planes creating Newton’s ring-equivalent interference colours across the translucent mineral surface.
Description
Muscovite mica is one of the most photogenic minerals in polarised light microscopy — its perfect basal cleavage produces sheets of extraordinarily uniform thickness that exhibit interference colours between crossed polarisers, the colours determined by the sheet thickness in the same way that soap film colours are determined by film thickness. This image was made using a freshly cleaved mica sheet placed on a light box between two crossed linear polarisers, the varying thickness of the cleavage surfaces producing interference colours ranging from yellow through red, violet, blue, and green in a complex topographic colour map. Where the sheet thickness is uniform, the colour is constant; at cleavage steps and inclusions, the colour changes abruptly. Shot at 2:1 reproduction with a macro lens, the entire cleavage surface is visible, the colour map serving as both a scientific thickness measurement tool and a vivid abstract composition.
