Natural History
Natural History
Rhodochrosite on Manganite
No reserve
Lot Closed
December 3, 07:41 PM GMT
Estimate
3,000 - 4,000 USD
Lot Details
Description
Rhodochrosite on Manganite
N’chwaning Mines, Kuruman, Northern Cape Province, South Africa
3¾ by 2½ by 1½ inches (9.2 x 6.5 x 3.5 cm). Largest crystal 1¾ inches (4.3 cm). Custom lucite base.
This specimen features isolated groups of scalenohedral rhodochrosite crystals that have formed on a matrix of well-crystallized, jet-black manganite. The rhodochrosite shows deep cherry-red color and the largest crystal is doubly-terminated. There are some cleaved crystals near the top, common for this material.
Accented by streaks of white and ranging from alarming reds to subtle pinks, rhodochrosite is a relatively rare manganese carbonate mineral. Displaying crystal twinning and varying levels of transparency, rhodochrosite is highly celebrated, as evidenced by its status as Argentina's "national gemstone", and as the official state mineral of the U.S. state of Colorado.
Manganite is a manganese oxide that forms when rain water weathers clay and aluminum deposits. Its striated, prismatic crystals appear gunmetal to iron-black, often accompanied by rust colored streaks.