Several videos of epidote-group minerals in thin section, showing typical textures and optical characteristics. Supported by Boise State University and the US National Science Foundation.
Key characteristics: very high relief, either saturated ("magic marker") interference colors or anomalous blue or gray, can have either parallel (zoisite) or inclined (everything else) extinction.
00:00 Typical epidote
00:30 Pleochroic epidote
01:01 Lemon yellow and light blue interference colors
01:32 Clinozoisite (gray interference colors)
02:02 Zoisite (it might be clinozoisite...)
02:33 Igneous allanite (rare-earth element epidote)
03:03 Metamorphic allanite
03:33 Metamorphic allanite
04:04 Piemontite (Mn epidote)
04:35 Epidote with piemontite overgrowths
