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[bugrock]

Is there a simple way to reliably distinguish hausmannite from braunite?
Some crystalized specimens of both present as clusters of triangular faces.
Both are black or blackish and can be lustrous and superficially similar to
my eye although perhaps hausmannite more often presents as distinct
octahedral xls? But that's not enough to go on for all material.

Thanks

[alfredo]

I can think of two simple tests:

Hardness: hausmannite is slightly softer than feldspar or a steel file; braunite is slightly harder than those, so although the hardness is not tremendously different, it is possible to easily check it when well crystallized. (Won't work well when massive or fine-granular.)

Silica: Braunite has a small silica content which will remain insoluble after dissolution in acid, whereas hausmannite should dissolve completely.