GemGuide Gem Focus August 2022 Featuring: Rhodochrosite; a rose-colored ornamental gem rarely seen in transparent form…

Argentina’s “national mineral” and Colorado’s “state mineral,” rhodochrosite was first identified in Romania in the 1800s. As the name suggests in Greek, it comes in different shades of pink. Due to its South American sources, it is also known as "Rosa del Inca," "Inca Rose," or Rosinca.   Rhodochrosite is a manganese carbonate mineral (MnCO3) with low hardness of 4 and three directional perfect cleavage. The structure is very similar to calcite since it is a calcite group mineral with remarkable coloration thanks to manganese. Despite its low durability, rare transparent red, orange-pink crystals are faceted and used in jewelry. Transparent rhodochrosite is highly sought after by collectors, especially when sourced from Colorado’s Sweet Home Mine. There are other transparent rhodochrosite sources such as the Kalahari region in South Africa and the Pallasca Province in Peru. However, neither of these sources has provided regular production. On the other hand, the massive form of rhodochrosite is produced in many localities in the world, most notably Argentina. Other localities include Romania, Germany, New South Wales in Australia, Tasmania, Mexico, and China.   Rhodochrosite and lapis lazuli inlayed box measuring 6 x 4⅛ x 2 inches. Courtesy of Heritage Auctions. Rhodochrosite has been used as an ornamental material for carvings, beads, and inlays, due to its low hardness for a very long time. Beautiful pink color contrasting with white banding in massive form is the typical appearance of the massive material. The pink and white banding is also called “bacon stripe pattern” and the most valuable ones are translucent with concentric banding revealing the stalactitical formation. While smaller, individual stalactites are sliced to be used in jewelry, larger pieces and grown together columns are cut into large plates as display pieces. Aesthetic plates are collectable and demand high purchase prices per object. Such pieces are best known from Argentina and Peru, although same sources may produce facet grade single crystals too. A 21.86 ct rhodochrosite from Sweet Home Mine, CO. Courtesy of Mayer and Watt. Photo by Geoffrey Watt. The Sweet Home Mine in Colorado, however, has been known for its stunning, transparent, single crystals suitable for faceting since the 1800s. More economical mining techniques of the later part of the 20th century made the transparent red rhodochrosite a collector’s gem. Collectors are aware that Sweet Home Mine demands a premium, yet the deeper red stones from South Africa may be as expensive since the source is diminishing now. China also produces nice transparent pink material at more affordable levels.     Vividly colored, transparent faceted rhodochrosite is sold at higher per carat prices, while the massive form is generally sold by per gram in most cases, per piece when it is a polished slice or carving. Strands of polished beads are available and priced per strand. Buyers need to be aware of simulants such as glass or resin since the pretty pink color with white banding is easily imitated in carvings and beads. Also, another massive gem material rhodonite with similar color pink is confused with rhodochrosite but standard gemological testing should resolve that issue.