They are not glassy at all. Ok, maybe they devitrified, unlikely, but possible. Well, then how are they all so perfectly round? Why is the size distribution so limited? If they formed in space, as some unknown type of chondrule, then at least a good fraction would have become unrounded on re-entry, and show signs of ablation. If they formed as tektites, molten material thrown out by impacts which rapidly cools to glass, then how is it that none of them have the teardrop, disk, or dumbell shape typical of tektites? Being composed principally of hematite, where is the source rock that could have produced them? While there are several other theories which are still plausable, your tektite theory lacks credibility.