Bull Domingo Mine - Custer County, Colorado

Mineral Collecting and Site Information

Site Description & Mineral Collecting

The Bull Domingo Mine is located a few miles north of the town of Silver Cliff in the Bull Domingo hills.The mine was mainly a silver and manganese producing mine. It was not your typical kind of mine in that it was a replacement deposit mine meaning that the main paying minerals were deposited there as a coating or an agate/banded type of occurrence on the existing rocks. Because of this rather unique mineral occurrence, it is one of my favorite locations. Hunt anywhere on the mine dump but below the remaining structure is where most of the collected specimens were found. On our first trip here, I came across a very nice piece of red chalcedony within 5 minutes. After a few minutes more we started finding very nice pieces of yellow, white and brown chalcedony as well as a beautiful transparent specimens of smithsonite. We also found many specimens of ankerite, siderite, sphalerite, galena, and chalcopyrite & chalcocite crystals. I also found many large rocks the size of large grapefruits to the size of bowling balls. These large rocks have a distinct coating of galena crystals, but upon breaking them open, found that they were a completely different type of rock on the inside which describes the replacement deposit structure of this mine. Most of the nice specimens we found were on little plates already broken apart from the host rock. These plates have 2 or 3 and sometimes 4 to 5 different minerals, which make for very nice display pieces. My wife came across a very nice piece with siderite crystals and 2 nice chalcopyrite crystals and some quartz. It is a very attractive cabinet piece that I am hoping she will part with one day!