Unframed Colombo Gold Mine, Sierra City, California map. November 1930. A write up on this mine can be found on page 301 of the 1885 book Gold Mines and Mining in California. The Colombo Mine consists of 22 claims and takes up 465 acres of government land. The mine was acquired by Sierra Minerals in 2018 and has been operated by them since. Dimensions: 24"h x 50"w. Please contact packshippros.com for shipping quote. Wear, toning, creases and discolorations. Please see photos.