I’d like to draw the list’s attention to “Birefringence”, an App for iOS devices. The app offers configurable and fully interactive Michel-Lévy color charts, interactive Reith-Sorenson charts, and a database of 562 minerals with optical and physical properties of each mineral. The app is collaboration between me and Frank Mazdab (of RockPTX.com<http://RockPTX.com>). I feel that the app offers the best color charts available anywhere, with a true representation of the colors you observe in your polarised light microscope, and their configurability and interactivity is unique. I’d love to hear your feedback. You can download the app here: https://itunes.apple.com/us/app/birefringence/id1354688131?mt=8 Please do leave a review! Regards, Andrew