Calcite
Description
Calcite is a carbonate mineral that crystallizes in more forms than any other mineral. This image was scanned using transmitted light through a single calcite crystal. These have a rhomboidal form (which has here been digitally skewed to orthogonal) and display an optical property called birefringence or double refraction that was first described by the Danish scientist Rasmus Bartholin in 1669. ‘Pure’ calcite crystals may appear optically clear but most are filled with cracks and other features that render them amenable to scanning. The results, however, cannot be guessed at by eye, and I have to scan dozens to get a single captivating image like this.