Manganite

Object/Artifact

-

Crater Rock Museum

Name/Title

Manganite

Entry/Object ID

2004.1.28

Description

Assemblage Zone: pegmatite dikes Chemical Composition: MnO(OH), Manganese Oxide Crystal System: Monoclinic System Description: Common Name: Manganite Group Name: Oxides and Hydroxides Chemistry: MnO(OH), Manganese Oxide Hydroxide Location: Ilfeld, Germany Description: Black cylender shaped crystals with a white background. PHYSICAL CHARACTERISTICS: Color is black to steel gray. Luster is metallic to dull in weather specimens. Transparency: Crystals are opaque, translucent in only thin splinters. Crystal System is monoclinic; 2/m Crystal Habit is typically short prismatic crystals that have a psuedo-orthorhombic shape. The terminations are generally blunted with domes and minor pyramid faces. The crystals are striated lengthwise. Crystals are usually grouped into tight bundles and columnar, massive and fiberous forms are also known. Penetration and contact twinning does occassionally occur. Cleavage is perfect in one direction lengthwise and good to fair in two other directions, one lengthwise at near right angles to the first one and one basal. Fracture is uneven. Hardness is 4 Specific Gravity is 4.3 (average for metallic minerals) Streak is reddish to brownish black. Associated Minerals are calcite, barite, garnets, limonite, siderite, pyrolusite and other manganese minerals. Other Characteristics: Alters to pyrolusite which can coat the crystals, dulling the luster and can affect a streak test. . Best Field Indicators are crystal habit, luster, striations, color and streak. Fracture: uneven Hardness: 4 Flourite Luster: Metallic Occurrence: Manganite is a mineral. Its composition is manganese oxide-hydroxide, MnO(OH), crystallizing in the orthorhombic system and isomorphous with diaspore and goethite. Other natural polymorphs of MnO(OH) are groutite (orthorhombic) and rare feitknechtite (trigonal). Crystals of manganite are prismatic and deeply striated parallel to their length; they are often grouped together in bundles. Notable Occurrences include Cornwall, England; Harz Mts., Germany; China; Sterling Hill, New Jersey and Negaunee, Michigan, USA and Ukraine Specific Gravity: 4.3 Streak: reddish to brownish Variety: Manganite was a valuable manganese ore when it was found in plentiful deposits. Now its rarity has relegated it to the standing of a minor ore dispite its high manganese content. Crystals are the chief indicator for identification. Only a few metallic minerals will have similar crystals (such as enargite) and these can be eliminated by means of comparing manganite's reddish streak and hardness. Pyrolusite is softer and has a bluish streak. If manganite is massive, it is difficult to distinguish it from other manganese minerals. Fine crystals of manganite can make a nice addition to a mineral collection.

Collection

Suomynona Mineral Collection, Suomynona Collection

Acquisition

Accession

2004.1

Source or Donor

Suomynona Mineral Collection

Acquisition Method

Donation

Dimensions

Width

3 in

Depth

3 in

Length

4-1/4 in

Weight

2 oz

Dimension Notes

Dimension taken at widest points

Location

Location

Display Case

FS-16

Room

Frieda Smith Hall

Building

Crater Rock Museum

Category

Permanent

Moved By

Curtis Gardner

Date

May 25, 2023

Notes

Added current location