View source for File:PLM5 twinning in gypsum particle XPL 200x.jpg


Photomicrograph of a sample of gypsum mixed with wheat starch grains stained with an organic red dye. Note the twinning observed in the central gypsum particle. Gypsum was confirmed with FTIR-ATR analysis (Colonial Williamsburg Foundation). Transmitted PPL, 200X. Examined with a Nikon NiU upright polarizing light microscope, image captured with DSRi1 Pixel-shifting camera and Nikon Elements Basic Research software. Colonial Williamsburg Foundation, Materials Analysis Laboratory. 

This sample was collected from an object in the Colonial Williamsburg Collection: CWF1950-593, Oval Box with Tooth Cleaning Powder, French, 1750-1830

Photo credit: Kirsten Moffitt, Colonial Williamsburg Foundation