Thin chains of epsom salt crystals photographed with a microscope in cross-polarized light.

 

When forced to grow mostly in two dimensions, epsom salt crystals form some beautiful chains and arrays of long finger like structures.  These crystals were grown by placing a drop of water saturated with dissolved epson salts onto a microscope slide and then placing a coverslip over the top.  The coverslip sits atop a single layer of tape at each end, this creates a thin layer above the microscope slide in which the crystals can form.