Rock ID

[itchmesir]

Please help me out if you can... sorry i dont have a picture.. my camera can not get a clear close up shot of the specimen.. here's what i know though..

it has rather flat rectangular crystalline form..

it's foliated

brittle

harness of ~5.. my steel blade barely scratches it

translucent

shiny luster.. not dull

was found in the Root River valley(mn) if that helps at all

edit: found my camera...

[mainbutter]

...calcite? I'm very unsure, but that's my best guess.

I think calcite reacts with Hydrochloric acid for confirmation.

[itchmesir]

...calcite? I'm very unsure, but that's my best guess.

I think calcite reacts with Hydrochloric acid for confirmation.

I thought calcite as well... but i don't have any hcl...

[Rodbldr4fun]

Try scratching a surface for hardness. Can you scratch it with c finger nail? Calcite has a Mohs hardness of 3.0; a finger nail is 2.5. If your nail won't try a knife blade. If a knife scratches it is likely calcite. Also, other acids will cause it to bubble if strong enough.

[itchmesir]

It's around 5.. i was able to scratch it with a steel blade

[Rodbldr4fun]

It is probably calcite. A steel blade can scratch it.