This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Birnessite Rancieite Aegirine Opal Microcline DemixVarennes quarry SaintAmable sill Quebec Canada. Pseudomorph of birnessite probably after serandite Thanks to Laszlo Horvath for information regarding the ranciite The microcline is white The olive green urchins are aegirine very typical for STA There are few small colorless droplets