Name/Title
RhodochrositeEntry/Object ID
2004.1.32Description
Assemblage Zone: pegmatite dikes
Chemical Composition: MnCO3, Manganese Carbonat
Crystal System: Tetragonal System
Description: Common Name: Rhodochrosite
Group Name: Calcite
Chemistry: MnCO3, Manganese Carbonate
Location: Hotazel Mine, South Africa
Description:
PHYSICAL CHARACTERISTICS:
Color is red to pink, sometimes almost white, yellow and brown.
Luster is vitreous to resinous.
Transparency: Crystals are transparent to translucent.
Crystal System is trigonal; bar 3 2/m.
Crystal Habits include the rhombohedrons and scalahedrons with rounded or curved faces that can obscure the crystal shape. Some crystals can be flattened to a bladed habit and these are sometimes aggregated into rosettes or minute crystals into spherules. Also botryoidal, globular, stalactitic, layered, nodular, vein-filling and granular. Twinning is somewhat common forming penetration twins and contact twins similar to calcite's twins.
Cleavage is perfect in three directions forming rhombohedrons.
Fracture is uneven.
Hardness is 3.5 - 4.
Specific Gravity is approximately 3.5 (above average)
Streak is white.
Other Characteristics: Pink and white banding in massive forms, non-fluorescence and specimens effervesce easily with dilute acids.
Associated Minerals include calcite, ankerite, alabandite, rhodonite, bementite, spessartine, fluorite, manganite, quartz and many metal sulfides.
Best Field Indicators are color, crystal habit, reaction to acid, non-fluorescence and perfect cleavage.
Fracture: uneven
Hardness: 4 Flourite
Luster: Vitreous
Occurrence: Rhodochrosite is a manganese carbonate mineral with chemical composition MnCO3. In its (rare) pure form, it is typically a rose-red color, but impure specimens can be shades of pink to pale brown. The streak is white. Its Mohs hardness varies between 3.5 and 4. Its specific gravity is 3.5 to 3.7. It crystallizes in the trigonal system. The cleavage is typical rhombohedral carbonate cleavage in three directions. Crystal twinning often is present. It is transparent to translucent with refractive indices of n?=1.814 to 1.816, ne=1.596 to 1.598. It is often confused with the manganese silicate, rhodonite, but is distinctly softer.
Rhodochrosite forms a complete solid solution series with iron carbonate (siderite). Calcium, (as well as magnesium and zinc, to a limited extent) frequently substitutes for manganese in the structure, leading to lighter shades of red and pink, depending on the degree of substitution. It is for this reason that the most common color encountered is pink.
Rhodochrosite occurs as a hydrothermal vein mineral along with other manganese minerals in low temperature ore deposits as in the silver mines of Romania where it was first found. Banded rhodochrosite is mined in Capillitas, Argentina. Catamarca, Argentina has an old Incan silver mine that has produced fine stalactitic examples of rhodochrosite that are unique and very attractive. Cut cross-sections reveal concentric bands of light and dark rose colored layers. These specimens are carved and used for many ornamental purposes.
Notable Occurrences are numerous and include the famous Sweet Home Mine, Alma, Park County and American Tunnel, Silverton, Colorado; Butte, Montana; the mines of Franklin, New Jersey; Humboldt Mine, Cochise County, Arizona and many sites in California, USA. Also found in Catamarca, Argentine; Huaron Mine and several mines in Ancash Department, Peru; Kara oba, Kazakhatan; Sacrimb, Transylvania, Romania; Cornwall, England; Harz Mountains, Germany; Tsumeb, Otavi, Namibia; Santa Eulalia and Magdalena, Mexico; N'Chwanging Mine, Hotazel, South Africa; Mont Saint-Hilaire, Quebec, Canada and many other localities from around the world.
Specific Gravity: 3.4-3.6
Streak: white
Variety: Rhodochrosite (whose name means rose-colored) is a very attractive mineral with an absolutely one-of-a-kind, beautiful color. Although it can be an ore of manganese, it is its ornamental and display specimen qualities that make it a very popular mineral. The color of a single crystal can just astound the observer with its vivid pink-rose color that seems to be transmitted out of the crystal as if lit from within.
Individual crystals are found in well shaped rhombohedrons and more rarely scalahedrons. In a massive form its pink and white bands are extremely attractive and are often used in semi-precious jewelry. Rhodochrosite is often carved into figurines and tubular stalactitic forms are sliced into circles with concentric bands that are truly unique in the mineral kingdom. Fine crystals are sometimes cut into gemstones, but rhodochrosite's softness and brittleness limit it as a gemstone for everyday use.Collection
Suomynona Mineral CollectionAcquisition
Accession
2004.1Source or Donor
Suomynona Mineral CollectionAcquisition Method
DonationDimensions
Width
1 inDepth
2-1/2 inLength
4 inWeight
1.46 ozDimension Notes
Dimension taken at widest pointsLocation
Category
PermanentMoved By
Curtis GardnerDate
May 25, 2023Notes
Added current locationLocation
Container
centerDrawer
middle tierShelf
east sideCabinet
case #62Wall
south of centerRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
Permanent
