2.2" Green Prehnite Crystal Cluster - Morocco
This is a specimen of green prehnite found in Morocco. The prehnite crystals formed in seemingly striated patterns in an almost botryoidal aggregation.
Prehnite is a calcium aluminum silicate with the chemical composition Ca2Al(AlSi3O10)(OH)2. It generally occurs as volcanic cavity infillings, and typically is a shade between yellow and green, however colorless and blue specimens are not unheard of.