Epidote

specimen number:
2133417

location:
Miracle Mountain Mine, Calaveras Co., California, USA

description:
A loose lustrous deep green sharply formed terminated crystal of epidote. In great condition. Good thumbnail for the species and locality.

The Miracle Mountain mine, located on Garnet Hill near Volcano in Calaveras County, California, is a specialized specimen locality recognized for producing sharp andradite garnet and epidote crystals. Geologically, the site consists of a contact metamorphic skarn deposit formed where Mesozoic granitic intrusions of the Sierra Nevada Batholith contacted Paleozoic carbonate sedimentary rocks, such as limestone. This intense thermal and chemical interaction resulted in localized metasomatism, creating rich silicate zones containing massive andradite rock along with open vugs or cavities that allowed individual crystals to grow unhindered. The primary minerals found in these cavities include brown andradite garnets displaying dodecahedral forms, along with associated epidote, albite, axinite-(Fe), and palygorskite. While small-scale prospecting for copper and industrial garnet occurred in the region during the late nineteenth and early twentieth centuries, active specimen extraction at the Miracle Mountain claim peaked during the late twentieth century, particularly around the 1980s, when field collectors systematically worked the skarn zones for mineral specimens.

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