TODOROKITE

(Na,Ca,K)_1-xMn⁴⁺₆O₁₂.3-4H₂O
Monoclinic

Todorokite, a manganese oxide hydrate mineral, was first reported from Sterling Hill by Frondel et al. (1960b), and it occurs at Franklin as well. Sterling Hill todorokite was crystallographically examined by Chukrov et al. (1978) and found to have a unit-cell translation of a = approximately 25 Å. There are no other physical or chemical data on local material. Local todorokite is distinctly dark brown or nearly black. Some todorokite specimens are replacements of ore in situ; others have a remarkable plumose texture that is both distinctly fibrous and leafy but highly irregular; such aggregates can be several cm in size. Sterling Hill todorokite occurs in the same assemblages as aragonite, hemimorphite, chalcophanite, birnessite, woodruffite, and Mn-oxides in the surface pits at Sterling Hill and is commonly associated with calcite, in some cases in vein assemblages. Franklin material is rare; it occurs with willemite and hemimorphite.

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This page created: January 11, 2001