Rhodochrosite with Quartz

specimen number:
2013504

location:
Sunnyside Mine, San Juan Co., Colorado, USA

description:
Pink rhombohedral crystals of rhodochrosite scattered across the top of a sparkling colorless crystallized quartz covered matrix. In good condition.

The Sunnyside Mine is located near Eureka in the Silverton District of San Juan County, Colorado, and stands as one of the most significant historical producers in the San Juan Mountains. Geologically, the deposit is an epithermal vein system associated with the collapsed Silverton Caldera, where mineralizing fluids circulated through volcanic rocks approximately 10 to 15 million years ago. Historically, the mine was discovered in 1873 and saw its greatest development under the Terry family, becoming a major source of gold, silver, and base metals. For mineral collectors, the Sunnyside is legendary for its vibrant, pink to cherry-red rhodochrosite. This manganese carbonate often occurs as sharp rhombohedral crystals or as unique, rounded "discoidal" habits that are highly sought after. These crystals are frequently found in aesthetic association with sparkling quartz, brassy pyrite, or dark sphalerite, creating a striking visual contrast. While the mine gained notoriety for the 1978 Lake Emma disaster, where water from a glacial lake breached the underground workings, it remains a premier locality for American rhodochrosite.

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