Since you haven't had an answer yet, I will pipe up. It's too hard to tell from the pictures - you could try to post some new pix taken in daylight, on a light background, with closeup of crystals. You could also take it (and a magnifying glass) to a local rock shop, gem/mineral club meeting, museum, geology dept. and let someone look at it first hand? I'm always encouraging people new to rockhounding to find a local club where the members are great at IDing local finds, and perhaps they have fieldtrips you can go on to find more!!
In any case, its a cool find - rocks with crystals are always fun. Keep lookin' down!
Tigger
