Rhodonite

Object/Artifact

-

Crater Rock Museum

Name/Title

Rhodonite

Entry/Object ID

2012.1.4

Description

Assemblage Zone: pegmatite dikes Chemical Composition: Fe3O4 Crystal System: Triclinic System Description: Common Name: Rhodonite Chemistry: (Mn, Fe, Mg, Ca)5(SiO3)5 , Manganese Iron Magnesium Calcium Silicate. Class: Silicates Location: Unknown Description: Angular, thin slab with polished face. Light, medium, to dark pink in an irregular formation, with some dark spotted areas intermixed. PHYSICAL CHARACTERISTICS: Rhodonite is a manganese inosilicate, (Mn, Fe, Mg, Ca)SiO3 and member of the pyroxenoid group of minerals, crystallizing in the triclinic system. It commonly occurs as cleavable to compact masses with a rose-red color (the name comes from the Greek: rhodos, rosy), often tending to brown because of surface oxidation. Color is typically pink to red or orange and even black. Luster is vitreous to dull to pearly on polished surfaces. Transparency: Crystals are generally translucent and rarely transparent. Crystal System is triclinic; bar 1 Crystal Habits include crystals that have a blocky prismatic habit, however crystals are rare. More typically massive, coarse and fine granular aggregates. Cleavage is perfect in two directions forming prisms with a rectangular cross-section. Fracture is conchoidal. Hardness is 5.5 - 6.5. Specific Gravity is approximately 3.4 - 3.7+ (above average for translucent minerals) Streak is white. Associated Minerals are calcite, pyrite, microcline, spessartine, pyroxmangite and other manganese minerals. Other Characteristics: May tarnish to a brown or black color upon exposure. Best Field Indicators are color, black inclusions, lack of reaction to acid and hardness. Fracture: conchoidal Hardness: 6 Orthoclase Luster: Vitreous Occurrence: In the iron and manganese mines at Pajsberg near Filipstad and Långban in Värmland, Sweden, small brilliant and translucent crystals (pajsbergite) and cleavage masses occur. Fowlerite occurs as large, rough crystals, somewhat resembling pink feldspar, with franklinite and zinc ores in granular limestone at Franklin Furnace in New Jersey. Rock Type: Metamorphic Specific Gravity: 3.4 - 3.7+ Streak: white Variety: The manganese is often partly replaced by iron, magnesium, calcium, and sometimes zinc which may sometimes be present in considerable amounts; a greyish-brown variety containing as much as 20% of calcium oxide is called bustamite; fowlerite is a zinciferous variety containing 7% of zinc oxide. Pink rhodonite contrasting with black manganese oxides is sometimes used as a gem material, from Humboldt Co., Nevada, USA. The inosilicate (chain silicate) structure of rhodonite has a repeat unit of five silica tetrahedra. The rare polymorph pyroxmangite, formed at different conditions of pressure and temperature, has the same chemical composition but a repeat unit of seven tetrahedra. Other varieties: Snowflake Rhodonite Crystalline Rhodonite ( Australia) Highly Crystalline Silicified Rhodonite ( Australia )

Collection

Carol Swisher Mineral-Uses Collection

Acquisition

Accession

LN2012.1

Dimensions

Width

2-3/16 in

Depth

3/16 in

Length

4-5/8 in

Dimension Notes

Dimension taken at widest points

Location

Location

Container

back row

Drawer

left

Shelf

top shelf

Cabinet

Mineral Uses

Wall

west wall

Building

Museum Entrance Hallway

Category

Permanent