Sorry don't know what it is. But if I were you I would get the Audubon Society's guide to Rocks & minerals & take it with you to ID, Is this a cave you have found? If so, be aware there is a disease spreading through our bats that can be carried out of the caves on our shoes. I don't know where you live, but here in MO It is taking it's toll on our bats. (not transferrable to humans). It's called white nose or something to that affect.
The pics are quite nice. I like the last one.