Description
Prehnite is a Phyllosilicate mixture of Calcium and Aluminum. Although it is not a Zeolite, it is often associated with them and with Datolite and Calcite, in veins and cavities of Basaltic rocks, sometimes in Granites, Syenites or Gneisses. The color varies from light green to grey to white to yellow or a mix of colors. It is translucent and was named after its discoverer, Colonel Hendrik von Prehn.
Epidote is an abundant rock-forming mineral, but one of the secondary origin. Many of the characters of the mineral vary with the amount of iron present. Prismatic, columnar crystals, often shiny, finely striated faces. The color is green, gray, brown or nearly black but usually a characteristic shade of yellowish-green or pistachio green.