i am an novice at mineral and stone collecting, and i am having a hard time at identifying what these even are, i found these on a railroad covered mostly with volcanic stones which where grinded to a smaller size. they appear to be some sort of glassy material with marks from oxygen bubbles left. i tried to scratch glass with a smaller fragment and it did leave a mark, although not to deep.
1st picture of the first stone:front2nd picture of the first stone: backside1st picture of the second stone: top view
if you could help me identify what this is i would be very grateful!
thanks for reading!