Sudoite


Sudoite is a mineral from the chlorite group. It was named after Toshio Sudo, professor of mineralogy at the University of Tokyo, in Japan, and a pioneer of clay science. The mineral tosudite also bears his name. It was approved as a valid species by the International Mineralogical Association in 1966.

Characteristics

Sudoite is a clay mineral with chemical formula defined as Mg2Al3O108. It has a monoclinic crystal system. Its hardness on the Mohs scale is between 2.5 and 3.5.

Classification

Following the Nickel–Strunz classification, it is contained in the "09.EC.55" group:
MineralFormulaSymmetry groupSpace group
Baileychlore1 or C1 or C
Borocookeite 2/mC2/m
Chamosite2/mC2/m
Clinochlore2/mC2/m
Cookeite, 2 or 2/mC, C2 or Cc
Donbassite2/mC2/m
Franklinfurnaceite2C2
Glagolevite1C1
Gonyeriteunknown
Nimite2/mC2/m
OdinitemCm
Orthochamositeunknown
Pennantite2/mC2/m
Sudoite2/mC2/m

Formation

It has been first discovered in the Knollenberg Keuper formation, in the village of Plochingen, Stuttgart Region. Despite being an unlikely mineral, it has been described in every continent but Antarctica and Oceania. It is found mainly in hydrothermal or high-pressure/low-temperature metamorphism contexts

Use

This mineral has been used as gemstone for the production of personal ornaments, beads and pendants, during the Early Ceramic Age, in the Lesser Antilles. The precise source of such formation of sudoite allowing to carve artifacts in rather large blocks remain unknown.