Andradite

specimen number:
2282032

location:
Green Fire Mine, San Benito Co., California, USA

description:
Lustrous green crystals of andradite, this is the variety known as demantoid, across the top of matrix. In good condition. Collected by Chuck Trantham.

The Green Fire mine, located on Santa Rita Peak within the New Idria mining district of San Benito County, California, is a specialized mineral locality famous for its vibrant green demantoid garnets. Geologically, the deposit sits within the massive New Idria serpentinite body, an ancient Mesozoic ophiolite block consisting of altered mantle peridotite that was tectonically emplaced into the California Coast Ranges. Hydrothermal and metamorphic fluids circulating through this calcium-rich, highly sheared ultramafic environment induced the crystallization of lustrous, chromium-bearing andradite crystals, varying from bright yellowish-green to deep forest green, sitting directly on a serpentinite matrix. Small-scale exploration, prospecting, and specimen mining operations at the site have been conducted intermittently since the mid-to-late twentieth century, driven primarily by independent mineral collectors seeking classic regional gem-quality garnet specimens.

Charles "Chuck" Trantham was a highly respected geologist and field mineral collector based in California who left a significant mark on the West Coast mineral community. Combining his professional geological expertise with a deep passion for field collecting, Trantham operated CT Minerals for decades, supplying collectors and museums with precisely documented regional specimens. He is particularly remembered for his work in the field during the 1970s and 1980s, which included field-collecting uncommon minerals at various California localities, such as the Junnila benitoite claim in San Benito County and occurrences in Plumas County.

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