These attractive lime green fluorites occur covered in Quartz, in this remote south African mine. As part of the prepping, the fluorites are immersed in Hydrofluoric acid (think of the blood in the movie Alien that dissolves metal) that dissolves Quartz but not the Fluorite. There are current major problems with production at the mine, and future mining is uncertain. 

This gemmy richly colored well formed fluorite cluster is handsomely "frosted" with druzy quartz. The largest fluorite measures 2.2 cm long. No damage.