“Gem silica is a bluish green to greenish blue variety of chalcedony that receives its vivid color from the presence of copper. It is often known as "chrysocolla chalcedony" or "gem silica chrysocolla."
The names "chrysocolla chalcedony" and "gem silica chrysocolla" are used because the green to blue color of gem silica is related to chrysocolla. Some references state that the color is caused by minute inclusions of chrysocolla within the silica. Others attribute the color to the same copper salts that give chrysocolla its color. Gem silica is the most valuable variety of chalcedony.” (From geology.com)
Locality: Erongo Mtns, Namibia
*Video taken in bright sunlight