History · Geology
About Sweet Home Mine
The Sweet Home mine near Alma, Colorado, is the world’s premier source of gem-grade rhodochrosite — its raspberry-red rhombohedral crystals from the “Alma King” pocket and successor pockets are essentially the species’ modern definition. Active collector mining ran from 1991 to 2004.
Geology
The Sweet Home is a small Tertiary epithermal Ag-Pb-Zn vein in the Colorado Mineral Belt, where late-stage Mn-rich hydrothermal pulses crystallized rhodochrosite into open vugs and miarolitic cavities, accompanied by quartz, fluorite, and tetrahedrite.
Notable Minerals
Rhodochrosite (gem-clear scalenohedral and rhombohedral crystals up to 15 cm — global standard), quartz, tetrahedrite, fluorite (purple cubes), pyrite, galena, sphalerite. The “Alma King” rhodochrosite (extracted 1992) is the largest known specimen and resides at the Denver Museum.
Collector Notes
Sweet Home rhodochrosite is the species type-quality and commands premium prices: top thumbnails $5,000+, museum-grade cabinet specimens six-figure prices. The mine is now closed; supply is essentially fixed.
Minerals Produced Here
- Agate (玛瑙)
- Amethyst (紫水晶)
- Chalcedony (玉髓)
- Citrine (黄水晶)
- Fluorite (萤石)
- Galena (方铅矿)
- Jasper (碧玉)
- Pyrite (黄铁矿)
- Quartz (石英 / 水晶)
- Rhodochrosite (菱锰矿)
- Rose Quartz (玫瑰石英)
- Sphalerite (闪锌矿)
- Tetrahedrite (黝铜矿)
