Bementite from Franklin
Bementite {Mn8Si6O15(OH)10} is found at Franklin, New Jersey and only a few other places on earth. This rare mineral is in the same series as schallerite and friedelite.

This piece came from the Buckwheat Dump during the summer of 1998. It was a rock that looked fairly uninteresting at first, except for one thing which caught my eye and made me pick it up. I wanted to see what was inside, because there were weathered, foliated masses of something on the outside of it. It was just a little bit different from the other rocks around it, but only if you looked at it closely.

It wasn't in the area of the dump where ore rocks usually occur.  It was actually up toward the steep bank, that part of the dump where there's a lot of dolomite, basalt, and "pegmatite" rocks.

The rock was very hard to break.  When it cracked open, it revealed what you see in the picture above. I didn't know what it was, so I took it to John Cianciulli and he identified it as bementite, a rare silicate mineral and a Franklin classic.

Specimen is about 2.5 inches across.

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