Hausmannite is a manganese oxide mineral. Few analytical data exist. McSween found the hausmannite associated with manganosite to have SiO2 0.3, Al2O3 0.51, FeO 5.85, MgO 0.16, MnO 11.53, Mn2O3 69.01, ZnO 12.91, total = 100.00 wt. %. This material has Zn:Mn2+ nearly 1:1 and is thus intermediate in composition between hausmannite and hetaerolite. The acicular crystals from the groutite assemblage have SiO2 0.3, Fe2O3 0.4, MgO 0.4, ZnO 0.8, MnO 29.2, Mn2O3 69.8, total = 100.9 wt. %, with Mn2+ assumed and calculated according to the known stoichiometry of hausmannite. Additional specimens from this assemblage were observed by [Dunn] which, although not chemically analyzed, yielded X-ray patterns much closer to that of hausmannite than that of hetaerolite.
Hausmannite was reported by Frondel (1972) to have been known from Franklin and Sterling Hill by Palache and Bauer, respectively, early in the century, but not described. An occurrence with manganosite was described by McSween (1976). It is a rare mineral locally.
Hausmannite occurs as massive fine-grained material, equant crystals, and subparallel fascicles of acicular 2-3 mm crystals. Its color varies from predominantly black to rarely reddish-brown. No physical or optical measurements have been made. Much of this material is microscopic.
Hausmannite is not a common mineral locally. Occurrences are few and minor, but many occurrences may exist unrecognized.
Hausmannite occurs as thin rims of fine-grained material which separates zincite from manganosite in some specimens of the Franklin zincite-manganosite exsolution assemblage. Its relative abundance in this assemblage has not been studied.
Hausmannite is also known as reddish brown, stiff, prismatic crystals, arranged in subparallel slightly divergent aggregates, within the groutite and brown andradite assemblage described herein. In this assemblage, it can be associated with groutite, cahnite, calcite, and kentrolite (Dunn, 1987). It has also been found as 0.5 mm prismatic crystals with flinkite and jarosewichite.
Hausmannite rarely occurs as superb, euhedral crystals of pseudo-octahedral habit in solution vugs in willemite and may occur unrecognized in other associations as well, especially in Zn-poor assemblages; in the presence of Zn, hetaerolite is more common. (Dunn, 1995)

 Location Found: Franklin
 Year Discovered: 1813
 Formula: Mn2+Mn23+O4
 Essential Elements: Manganese, Oxygen
 All Elements in Formula: Manganese, Oxygen
 IMA Status: Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
 To find out more about this mineral at minDat's website, follow this link   Hausmannite

Dunn, Pete J. (1995). Franklin and Sterling Hill New Jersey: the world's most magnificent mineral deposits. Franklin, NJ.: The Franklin-Ogdensburg Mineralogical Society. p.594

Frondel, Clifford (1972). The minerals of Franklin and Sterling Hill, a checklist. NY.: John Willey & Sons. p.60

The Picking Table References
 PT Issue and PageDescription / Comment
View IssueV. 34, No. 1 - Spring 1993, pg. 13The Flinktie / Cahntie / Jarosewichite Assemblage From Franklin, New Jersey, Vandall T. King - Hausmannite
View IssueV. 32, No. 1 - Spring 1991, pg. 15Mineral Notes, Research Reports, Manganese-Rich Ore Assemblages, Hausmannite (small description)
View IssueV. 28, No. 2 - Fall 1987, pg. 5Kentrolite, Groutite, Manganite, and Hausmannite From Franklin, New Jersey: Some Observations, Dr. Pete J. Dunn, Groutite, Manganite, Hausmannite
View IssueV. 19, No. 2 - September 1978, pg. 12The Post Palache Minerals by Frank Z. Edwards - Hausmannite (small article)
View IssueV. 7, No. 2 - August 1966, pg. 9The Minerals of Sterling Hill 1962-65 by Frank Z. Edwards - Hausmannite (small article)
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