EPIDOTE CRYSTAL SPECIMEN
An Epidote Crystal Specimen comprising of about half a dozen various sized crystals with partial crystals. Dark green almost black this specimen was hard to photograph.
4.7cm x 4cm x 2.2cm, 41g.
Shengus, Skardu, Pakistan.
Calcium Aluminum Iron Silicate Hydroxide
Epidote Crystal Habits include long, prismatic or tabular crystals. The terminations are wedge shaped or tapered pyramids. Many clusters show grooved slender crystals or acicular sprays. Also massive, fiberous or granular.
Epidote is a structurally complex mineral having both single silicate tetrahedrons, SiO4, and double silicate tetrahedrons, Si2O7. The two Aluminums represent the parallel chains of AlO6 and AlO4(OH)2 Octahedra that are the heart of the Epidote structure. The silicate groups and extra ions connect the chains together. Since the chains are parallel, the crystals tend to be prismatic. Epidote, while not general known for exceptional crystals can produce some magnificent specimens.
Color is “pistachio” green to yellowish or brownish green, also brown to black.
Luster is vitreous.
Transparency crystals are transparent to translucent.
Crystal System monoclinic; 2/m
Crystal Habits include long, prismatic or tabular crystals with a typically dominant pinacoid that the crystal is often flattened against. The terminations are wedge shaped or tapered pyramids. Many clusters show grooved slender crystals or acicular sprays. Also massive, fiberous or granular.
Cleavage good in one direction lengthwise.
Fracture is uneven to conchoidal.
Hardness is 6-7
Specific Gravity is 3.3-3.5
Streak white to gray
Associated Minerals calcite, biotite, hornblende, actinolite, andradite garnet and other metamorphic minerals.
Other Characteristics: striated to the depth of grooves in some crystals.
Notable Occurances Untersulzbachtal, Austria; Italy; Baja, Mexico and many localities in the USA.
Best Field Indicators only one direction of cleavage, crystal habit, color and hardness.