Featuring: Rhodochrosite; a rose-colored ornamental gem rarely seen in
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.