Alma King

January 20, 2006

Picture_044 copy

Provided and copyright by: Claudia Perko, Clara Barton H.S., Brooklyn, NY
Summary authors & editors: Claudia Perko

This spectacular crystal of Rhodochorsite (MnCO3), known as the “Alma King” measures 14 cm x 16.5 cm. The perfect rhombohedron was recovered in the wall of a narrow pocket on a matrix of white, needle clear Quartz, blue Fluorite, black Sphalerite and Tetrahedrite, brasse Chalcopyrite and pale yellow Calcite. The “Alma King” was collected in 1992 from the Sweet Home Mine, which is located about 144 km southwest of Denver, Colorado, near the small old mining town of Alma. Sweet Home Mine was originally opened as a Silver mine in the 1870’s and was mined until the 1960’s. Throughout the mine’s lifetime, nice Rhodochrosite specimens were found along with the silver ore, but not used commercially. In 1991 the mine reopened as a Rhodochrosite specimen mine.

Rhodochrosites from the Sweet Home Mine are gem-quality crystals because of their translucent cherry-red color, which is due to the relatively low amount of iron, magnesium and calcium impurities. Note that when calcium, magnesium, and especially iron ions substitute for manganese, a pink color will result. Many experts acclaim the “Alma King” as the finest and most valuable mineral specimen ever mined in North America. Rhodochrosite became the Colorado State Mineral in 2002.

The “Alma King” can be seen in the permanent display in the Coors Mineral Hall at the Denver Museum of Nature and Science, Denver, Colorado. (Photo taken in July 2005, Canon Power Shot A80).

Related Links: