https://www.wacoca.com/media/648047/ Book Review: Gem Testing Techniques #book #books #gem #gemology #Gems&Gemology #GG #Hobby #Hodgkinson #lighting #optics #pleochroism #practical #RefractiveIndex #refractometer #Renfro #review #testing #ultraviolet #書籍

#ThinSectionThursday Plechroism in action: a wee gif showing pleochroic colour change in orthopyroxene (pale green-pink) + biotite (deep brown-pale brown) in this noritic rock from Govals, Aberdeenshire. Field of view about 2mm wide. #Microscopy #PolarizedLight #Pleochroism #Mineralogy #Geology