Auction Win: ‘Chocolate’ Calcite

Locality: Santa Eulalia Mining District, Aquiles Serdán Municipality, Chihuahua, Mexico

Size: Cabinet - 9.7 × 9.7 × 5 cm

Chocolate Calcite is a tan to chocolate-brown variety of calcite, a calcium carbonate mineral with formula CaCO3. This striking mineral, named for its rich color resembling chocolate, is commonly found in Chocolate Mountains, California, and is used in construction as a component of limestone and marble. Its vivid hue and lustrous appearance make it a favorite among collectors for display specimens.

Santa Eulalia Mining District in Chihuahua, Mexico, is one of the world’s most historically significant and prolific silver-producing regions, having operated continuously since 1703 and yielding over half a billion troy ounces of silver alongside massive quantities of lead and zinc. Geologically, it is the largest example of Carbonate Replacement Deposits in a 2200 km belt stretching from Hidalgo to the U.S. border, renowned for its rugged limestone and volcanic terrain divided into distinct West, East, and Middle mineralization camps. The district has produced world-class specimens of hemimorphite, willemite, calcite, pyrite, bromargyrite, and selenite, with the San Antonio Mine in the East Camp notably recognized as North America’s first economic tin mine and a source of significant vanadium. For collectors today, Santa Eulalia remains a top-tier locality for rare zinc minerals and high-quality base metal specimens, offering exceptional geological diversity and a legacy of over three centuries of mining excellence.