Colours in Citric Acid
Lately I experiment a lot with crystal growing and I knew that Citric Acid can refract the light, but when I saw this I was more than surprised. These flat crystals of about 1-2 cm in diameter (the larger ones) were grown between two glass plates, then put in front of a polarized light source and photographed with a polarization filter. It took a few tries to find a proper way to grow them flat enough for this purpose though. More Photos see here and here.
Author: Rolf Kohl, Germany
Posted on February 12, 2012, in miscellaneous phenomena, observations, polarization and tagged colours, glass plates, refraction. Bookmark the permalink. 1 Comment.
Atmospheric Phenomena 
Beautiful birefringence colours ( http://www.atoptics.co.uk/fz240.htm ).