2.6" Botryoidal Prehnite On Epidote - Mali

Prehnite is a calcium aluminum silicate with the chemical composition Ca2Al(AlSi3O10)(OH)2. It generally occurs as volcanic cavity infillings. It often displays colors between yellow and green, but colorless and blue specimens are not unheard of.

About Epidote

Epidote is a striking and often green mineral known for its complex crystal structure and vitreous luster. It is a calcium aluminum iron silicate that commonly forms in metamorphic rocks, particularly in regions that have undergone low to medium-grade metamorphism. The color of epidote typically ranges from pistachio green to dark green, although it can occasionally appear yellowish-green or even brown due to varying iron content.

Epidote crystals can appear in prismatic, slender forms or as aggregates, and they often exhibit striations along their length. The mineral’s translucent to transparent appearance and high refractive index give it an attractive, glassy shine.

It is commonly associated with minerals such as quartz, feldspar, and garnet, often forming in metamorphic rocks like schist and gneiss. It can also be found in skarn deposits alongside minerals like calcite, diopside, and amphiboles. These associations can provide insights into the geologic history and metamorphic conditions of the region. Epidote is found in locations worldwide, with notable sources including Austria, Norway, Pakistan, and parts of the United States. Collectors prize epidote for its unique green hues and well-formed crystal clusters.