Exceptional historical specimen of crystals of mamelonned lepidocrocite (variety of manganesiferous goethite).
Beautiful black and shiny nipple, perfectly proportioned, at the end of which point 3 beautiful nipples. Nothing to complain about!
Historical specimen delivered with its label of the XIXth century of the naturalist dealer Deyrolle of Paris, dealer still existing today.
Here is a video of this lepidocrocite from Rossbach, near Siegen in Germany:
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