Crystal system:             Tetragonal                               Hardness:          5.5

Density:                        4.7 - 4.84                                  Cleavage:         Perfect

Streak:                          Brown                                       Colour:             Black metallic

Occurrence: Occurs mainly in high temperature hydrothermal veins and in contact metamorphic deposits.

Habitat: Crystals are pseudo octahedral up to 7,5 cm.    Composition:    Mn2+ Mn3+2 O4


Following on last month’s “Mineral of the Month” we are looking at another black mineral from the Kalahari Manganese Fields near Kuruman, namely hausmannite.  

The mineral is named after Johann Friederich Ludwig Hausmann (1782 -1859), Professor of Mineralogy at the University of Gottingen in Germany, who discovered the mineral.  The type locality is Thuringia, Germany.  It has been described as a valid mineral specie since 1827.

Hausmannite has been found in the USA, Brazil, England, Scotland, Sweden, Italy, Switzerland, Belgium, Germany, Bulgaria, Morocco, India, Namibia and South Africa.

Hausmannite is one of the rare minerals exploited for manganese and is not commonly found as well formed crystals.  Crystals are formed in a variety of different habitats, with the “pagoda” form of many specimens from the Kalahari Manganese Fields, being the most attractive and the most sought after.


Hausmannite on andradite garnets from the N’Chwaning II mine, KMF.

Specimen and photo by – J de Jongh

References

Cairncross, Bruce, (1997) – The Manganese Adventure.

Cairncross, Bruce; Dixon, Roger, (1995) – Minerals of South-Africa.

Cairncross, Bruce, (2004) – Field Guide to Rocks & Minerals of Southern Africa.

Roberts, Campbell, Rupp, (1990) – Encyclopedia of Minerals Second edition.

www.webmineral.com,       www.galleries.com/Minerals        www.en.wikipedia.org