Oct 22, 2019
Fusions...
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Fusions...
Hausmannite w/ Andradite
Nchwanning Mine, South Africa
An unusual pseudomorph
It is common for one mineral to fake the shape of another since geological processes (usually involving hot fluids as they cycle in giant cells through the crust heated by depth or magma) frequently rearrange the geochemistry of rocks. Here we have one oxide of manganese (Hausmannite) replacing another (Manganite) taking on its distinctive crystal shape as opposed to its usual pseudo octahedral habit (ie looking like it crystallises in the cubic system like diamonds or fluorite, but actually doing so in another system, tetragonal in this case, but mimicking the shape of another). Our culprit varies from opaque brown through grey to black, and is relatively soft (5.5 on Mohs hardness scale) and was named in 1827 after a professor of mineralogy at Gottingen University who first described it, being renamed in his honour a couple of decades later by a colleague. Its type locality (where first discovered) is in the Thuringia region of Germany, where the 4.0 x 3.2 x 2.9 cm specimen in the photos comes from. It is also found in Arkansas, Sweden, the Ural Mountains and the Kalahari Manganese Field of South Africa and Namibia. Its typical form is as black granular aggregates, occurring in hydrothermal veins and metamorphosed manganese deposits, in this case replacing the original Manganite in a classic piece mined in the 19th century.
Loz
Image credit: Rob Lavinsky/iRocks.com
https://www.mindat.org/min-1832.html http://www.galleries.com/Hausmannite http://bit.ly/2zuGd5p
I FORGOT TO POST THEM anyway my new gemsonas bc im an idiot that changes everything all the time
Hausmannite atop Andradite Garnet covered Matrix
Size: 6.4 cm by 8 cm by 5.2 cm
Locality: N'Chwaning II Mine, Kuruman, Kalahari Manganese Fields, Northern Cape Province, South Africa.
Sturmanite Celestine and Hausmannite
Locality: N'Chwaning, North Cape Province, South Africa
Hematite, Hausmannite, Barite
N'Chwaning II Mine, N'Chwaning mining area, Kuruman, Kalahari manganese field (KMF), Northern Cape Province, South Africa
Hausmannite