Mcgillite is a rare, monoclinic, pseudohexagonal mineral of the Pyrosmalite group, with the formula Mn
8Si
6O
15(OH)
8Cl
2. It was first approved in 1979, and is named for McGill University.
Mcgillite is found in the Sullivan Mine, Kimberley, Kootenay district, British Columbia, Canada; the Kyurazawa mine, Tochigi Prefecture, Japan; and at one location in Romania. At the Sullivan mine, it forms as fracture fillings in a manganese-rich portion of quartzite and argillite within a metamorphosed lead-zinc deposit. It is pink in color.
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