Minnesotaite is an iron silicate mineral with formula: (Fe²⁺,Mg)₃Si₄O₁₀(OH)₂. It crystallizes in the triclinic crystal system and occurs as fine needles and platelets with other silicates. It is isostructural with the pyrophyllite- talc mineral group.

Occurrence

Minnesotaite was first described in 1944 for occurrences in the banded iron formations of northern

Minnesota Minnesota ( ) is a U.S. state, state in the Upper Midwestern region of the United States. It is bordered by the Canadian provinces of Manitoba and Ontario to the north and east and by the U.S. states of Wisconsin to the east, Iowa to the so ...

for which it was named. Co-type localities are in the Cuyuna North Range, Crow Wing County and the

Mesabi Range The Mesabi Iron Range is a mining district and mountain range in northeastern Minnesota following an elongate trend containing large deposits of iron ore. It is the largest of four major iron ranges in the region collectively known as the Iro ...

in St. Louis County. It occurs associated with

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

, siderite, stilpnomelane, greenalite and

magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula . It is one of the iron oxide, oxides of iron, and is ferrimagnetism, ferrimagnetic; it is attracted to a magnet and can be magnetization, magnetized to become a ...

.Gruner, John W., ''The Composition and Structure of Minnesotaite, a Common Iron Silicate in Iron Formations,'' American Mineralogist, 1944, 29, 363-372
/ref> In addition to the low grade metamorphic banded iron formations it has also been reported as an alteration mineral associated with

sulfide Sulfide (also sulphide in British English) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to large families o ...

bearing veins.

References

{{Phyllosilicates Phyllosilicates Triclinic minerals Minerals in space group 2