Epidote, Green Garnet and Tourmaline from Kunar, Afghanistan (RARE!)

The mineral group epidote consists of a number of sorosilicates, the most important of which is the mineral epidote. The mineral epidote is a calcium iron aluminum silicate with the chemical formula Ca2 (Fe3 +, Al) Al2 (SiO4) (Si2O7) O (OH). The yellow to brown-green, gray or black epidote has a glass luster, a gray-white stripe color and the cleavage is perfect according to crystal clear [001]. The crystal system is monoclinic. The average density is 3.45 and the hardness is 7. Epidote is not radioactive. The name epidote is derived from the Greek epidosis, which means "addition". Epidote is a very common mineral worldwide, especially in contact with metamorphic rocks. It is formed in crystalline limestone and in schist. Especially in the Knappenwand, near the Großvenediger in the Untersulzbachthal, Salzburg (Austria), beautiful epidote crystals are found. Epidote is common in the sand fraction of Dutch Quaternary river sediments. In the heavy mineral analysis as it took place in the Netherlands at the National Geological Survey during the second half of the twentieth century, the mineral is classified in the so-called unstable group.