Question What is this? Found at construction site in sand

May 5, 2020
I think it's glass of some kind, based on the smooth surfaces and lack of crystalization. Quartz, by comparison, has lots of crystalline structures and cleavage planes. My best guess is that something really hot landed in that spot, which caused the melting, but the surrounding material only held the heat in long enough for the initial melting, but not long enough for large crystals to form. What fractures we do see are probably due to uneven cooling.