Epidote

As mineral specimens go, epidotes are not as significant as many others and certainly lacks some visual appeal. Indeed there are more colorful, more beautiful, more valuable minerals that rank higher, nonetheless, it is still a worthy specimen to admire.

Epidote crystals appear in various forms. Crystals can be pyramidal, tabular to elongate, acicular, blocky or massive. Twinning is common and relatively easy to identify by a chevron pattern seen on the crystal termination. Fine crystals are also known to appear dark green to nearly black in color. In uncommon cases, epidote can be faceted but, it tends to be quite dark once cut. The yellowish color shows best in thins livers or the edges of gemmy crystals. When massive or fibrous epidote’s color it is most often a pistachio green. Pale green crystalline epidote is found abundantly in cracks and as coatings on faces of host rocks.

Knappenwand has long been the source of the world’s finest epidote found in substantial quantities since the mid 1800’s. For centuries, the Austrian source has been the most prolific producer of epidote, until recently, with discoveries in Pakistan.

The host rock is an epidote schistose rock, the result of hydrothermal alteration during secondary metamorphic action. Epidote is a prevalent rock-forming mineral formed in various localities ranging from medium temperature metamorphic environments to skarns, pegmatites, and contact metamorphic limestone.

The Austrian epidote crystals were found in crystallized clefts in schistose rock with amphibolite rock intruded by aplite, a fine-grained type of granite. Such an environment holds various elements necessary for epidote to form. The deposit was discovered when prospectors were looking for potential ore deposits. Once found, the Austrian epidote crystals set the standard for excellence of this common mineral that was not equaled until Pakistan began producing.

Austrian crystals are elongate, range in color from pale yellow-brown to pale to dark yellow-green. They generally have slanted terminations as one prism face is slightly longer. Crystals frequently show shallow vertical striations and readily develop clusters of sub-parallel growth in lathe-like crystals up to a foot in length.

In addition to Alaska’s Green Mountain, fine epidote has surfaced in Connecticut, Lemhi County, Idaho, Riverside, California and Colorado. The Colorado locality was worked for crystals for a time, but nothing has recently come from these localities. The same is true of Baja California Norte, at Gavilanoes, Castillo Real, Mexico, which produced quantities of single, well-terminated inch long blades with other species. Arundel, Norway and Alla Valley, Italy yielded fine crystals seldom seen today except when a collection is broken up and offered for sale.

Fortunately, when Pakistan started producing fine pegmatite minerals, it also yielded specimens of epidote, which many collectors feel rival the Austrian epidote specimens. Their crystal form, color, elongate crystals and sub-parallel clusters are every bit as nice as Austria’s best.

Epidote Lens

Pakistan epidote specimens first appeared from the Zard Mountains, Kharan, but it was not until alpine fissures were discovered in the Turmiq Valley near Shigar Valley that several deposits were found. The finest examples of epidote were found at Alchuri and Dassauin the Surdu District of Pakistan’s Northern areas.

Epidote is one of those species that offers collectors a nice variety of crystal forms from elongated to blocky crystals, from a lovely yellow-brown to yellow-green to nearly black. Its crystal forms vary, so you can collect a dozen epidotes, and they are all different in color, shape and associations with the added appeal of fine twinning. A suite of epidote crystals from worldwide sources has great eye appeal and is well worth owning.

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