Cordierite tutorial Optical mineralogy
Channel: Matt Kohn
Date: 2021-05-04

Several videos of cordierite in thin section, showing typical textures and optical characteristics. Supported by Boise State University and the US National Science Foundation.
Key characteristics: low relief (like quartz), black and white interference (like quartz), yellow pleochroic haloes around accessory minerals, alteration along fractures (penninitization).
00:00 Sillimanite clot with cordierite corona
00:30 Altered/fractured
01:01 Close-up of altered/fractured. Also pleochroic haloes
01:32 Yellow pleochroic haloes. Also some fracturing and alteration
02:03 Intense yellow pleochroic haloes
02:33 Intense yellow pleochroic haloes