Axinite-Fe

specimen number:
1115243

location:
New Melones Reservoir, Calaveras Co., California, USA

description:

Sharp lustrous bladed partly gemmy crystals of axinite across the front of matrix. Very slight damage along one edge of the matrix, considering the overall size of this piece a number of crystals present this is in super condition. A very fine palm-sized specimen for this famous locality. About as good as they can get in this size range.

The New Melones Reservoir area, situated along the hyper-historic Mother Lode gold belt in the rugged foothills of Calaveras and Tuolumne counties, California, United States, is an iconic geologic locality famous for producing exceptional specimens of ferro-axinite. Geologically, this complex region is characterized by late Paleozoic to Mesozoic metavolcanic and metasedimentary rocks of the Western Sierra Nevada Metamorphic Belt, which were intensely sheared and altered by the Melones Fault Zone. High-temperature hydrothermal fluids associated with Late Jurassic magmatic intrusions filled structural fractures and contact-metamorphic skarn zones, precipitating primary native gold and quartz alongside a highly localized, pristine concentration of large, lustrous, clove-brown to violet tabular crystals of ferro-axinite, often associated with epidote, albite, chlorite, and calcite. Historically, large-scale gold mining and copper quarrying dominated the river canyon from the 1850s gold rush through World War II, but the specific axinite-bearing outcroppings and localized prospects gained intense international attention during the mid-twentieth century as mineralogists rushed to salvage specimens ahead of infrastructural development. The entire historic canyon area was profoundly altered when the United States Army Corps of Engineers constructed the massive New Melones Dam across the Stanislaus River between 1966 and 1979, officially filling the reservoir and permanently submerging the primary axinite collecting ledges and older mine workings beneath hundreds of feet of water by 1980. Through 2026, while the reservoir functions strictly as a heavily restricted federal water management and recreation facility, the remarkable axinite specimens preserved in museum collections prior to the inundation remain a legendary historical and mineralogical benchmark for studying Sierran tectonic fluid flow and silicate crystallization.

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