Phyllosilicate (sheet silicate), chlorite group
Specific gravity: 2.63 to 2.68
Hardness: 2½ to 3½
Colour: White to light green
Solubility: Sometimes slowly decomposed by acids
Common impurities: Ti,Mn,Ca,K,H2O
Sudoite is found mainly as earthy masses of microscopic crystals. It is fairly widespread in a number of geologic settings, often coexisting
with other fine-grained minerals (R&M 85.4.324). It is found disseminated in hematite ore, probably
of hydrothermal origin, as as an authigenic mineral in aeolian sandstones, and in low-grade
At Ottré, Vielsalm, Luxembourg, Wallonia, Belgium, sudoite occurs in a low-grade metamorphic assemblage (HOM, R&M 85.4.324).
At the Kesselberg area, Triberg im Schwarzwald, Schwarzwald-Baar-Kreis, Freiburg, Baden-Württemberg, Germany, sudoite is formed by hydrothermal alteration of a quartz porphyry tuff (AM 48.214).
The type locality is the Knollenberg Keuper formation, Lützelbach, Plochingen, Esslingen, Stuttgart Region, Baden-Württemberg, Germany.
At Biesenrode, Mansfeld, Wippra Metamorphic Zone, Saxony-Anhalt, Germany, sudoite is associated with quartz, carpholite, manganoan garnet and hematite (HOM).
At Itaya, Gyogo Prefecture, Japan, sudoite is associated with pyrophyllite, diaspore, mica and böhmite (HOM).
At the Tracy Mine, Negaunee, Marquette county, Michigan, USA, sudoite is a constituent of hematite iron ore presumed to be of hydrothermal origin (HOM, R&M 85.4.324).
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