Bedded deposits in metasedimentary rocks of almandine-amphibolite facies contain braunite, hollandite, and hausmannite of two generations, plus bixbyite, vredenburgite, jacobsite, manganite, and hematite. The paragenesis of these minerals suggests that they formed by regional metamorphism of manganiferous sediments. Post-metamorphic lower-temperature dioxide ores with colloidal textures form replacement ore bodies that indicate considerable mobility of manganese.

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