The thread was getting long, so I am posting the original message with a direct link to the pictures of the glass rocks, hopefully this will help :)
I really appreciate whatever insights you can offer.
Can someone help me to identify glass stones?
My daughter and I where trekking a lake bed that had been drained in order to build a new dam and road. The entire floor looked like gravely sand, when we turned over a piece of the lake bed it was solid blue glass. To be clear, the entire bed of the lake is a solid chunky blue glass.
This is in an area that has no volcanic activity (recent) and we have been searching for answers to our mystery stones. I have pieces that look like solid blue glass tubes, around 6" in diameter. These I pulled from grouping of what look like tube vents of molten glass.
We also have red glass and a perfectly round red glass sphere. There are also very dense solid black glass pieces that seem oddly void, as if exposed to intense and sudden heat. I found these 11 years ago, since then the area around the site has been developed, however the site is still relatively unknown.
I have many pictures and would really appreciate some help in understanding these glass stones. Looking online we have wondered if they are formed from ancient volcanic activity, if they could be tektites and meteor blast glass, we have even considered the possibility of it being slag glass or from underground vents, either way, it would be nice to have this mystery solved :^P
I have posted some pictures here http://eternaldawn.net/glassrocks/ the photos do not show the blue of the stone clearly, they look very dark in the pictures, but I can assure you they are a very deep blue.
Thank you again for your insights,