Advance Mine (Zaca Mine; Zaca group; North Advance Mine; Collosus Mine; Colorado No. 2 Mine; Tarshish Mine)
Colorado Hill, Loope (Monitor; Loopeville), Monitor - Mogul Mining District, Alpine County, California, USA
Key Information
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The Advance Mine, also known as Zaca Mine, is located in Alpine County, California, in the Sierra Nevada mountains, near the small community of Loope.
It produced a variety of minerals, including gold, silver, and less common ones like hübnerite and oxyplumboroméite, appealing to crystal enthusiasts.
The mine’s geology features hydrothermal veins in volcanic and sedimentary rocks, formed through ancient volcanic activity.
Mining began in 1864, with significant operations until 1968, and it was owned by various companies over the years.
The area has a rich mining history tied to the California Gold Rush, with a culture influenced by Basque sheep raisers and early settlers.
The climate is temperate, with warm summers, cold winters, and significant snowfall, impacting mineral exploration.
Geographic Location
The Advance Mine sits in the rugged Sierra Nevada, part of Alpine County, California, known for its isolation and natural beauty. It’s in the Monitor - Mogul Mining District, near Colorado Hill and Loope (also called Monitor or Loopeville), with coordinates at 38° 39' 57'' North, 119° 42' 11'' West. Nearby settlements include Markleeville (7.5 km away) and Topaz Lake (14.2 km), reflecting the area’s sparse, rural character.
Minerals Produced
This mine is a gem for enthusiasts, yielding gold, silver, copper, lead, zinc, antimony, and tungsten. Notable finds include acanthite, arsenopyrite, and rarer minerals like hübnerite and oxyplumboroméite, adding to its allure for collectors seeking unique crystals.
Geological Structure
The mine’s geology is a story of Earth’s fiery past, with hydrothermal veins hosted in andesite, rhyolite, tuff, basalt, and sedimentary breccia. Ore bodies are tabular (120m thick, 15m wide, 125m long) and stockwork, surrounded by Tertiary volcanic deposits, with alterations like jasperoid pinnacles (65-95% quartz).
Mining History
Discovered in 1862 and operational by 1864, the mine was active until 1968, with key periods in 1867, 1912, and 1931-1941. It featured extensive workings, including tunnels over 304.8m long, and was owned by companies like Siskon Corp. and Western States Minerals Corp. Production included significant gold and silver, with reserves estimated at 8.5 million metric tons in 1996.
Local Culture and Characteristics
Alpine County’s culture is rooted in mining and agriculture, with Loope reflecting a small, unincorporated community. Historically, Basque sheep raisers and early settlers shaped the area, with social life centered around lyceum associations. The region’s isolation preserves a pioneer spirit, celebrated by local historical societies.
Climate and Ecology
The climate is temperate, with warm summers (July highs around 82°F) and cold winters (January lows 20°F), receiving 192 inches of snow annually. Spring is wettest (45% precipitation), and the area has 250 sunny days yearly. The ecology features pine forests and wildlife, adding to the adventure of exploring this mineral-rich terrain.