Rock from Southwestern Utah (Manganese)

[Drakien]

Found out this is Manganese.

I am trying to identify this rock. I was doing some exploration of an old mine, and this wall over the place. Just wondering what it is?

I have tried looking it up on "Mindat.org" but the mine wasn't listed, or anything in this particular rock formation.

It is roughly 3"x2.5"x1.5" and weighs 1/2lb.
It has a black crystalline structure that weaves around what appears to be a "non magnetic" dark brown layer.
When you scratch the black crystalline structure it turns a grayish, white. (as seen on the edges)

[arappaho]

Maybe a form of banded calcite, especially if the dark crystalline area
is easy to scratch. Sometimes called "cave onyx" but onyx is
improperly used to describe calcite based rocks.

[Drakien]

It is possible. The crystalline area is fairly easy to scratch. Not with your finger nail, but a key.

Just a few pics of under a microscope

[feidzd]

Why I never came across these strange things?

[Drakien]

So this is Manganese.