Dear Frank ! I do have a piece of Zhamanshinite (they look very different from Irgisites - they look more like bubble-rich Obsidian than tektites).I thought its an Impactit material but Russian local Scientists tried to insist that it is a tektite! I hope I find it in my big stock soon, I will send it to you if you want . Weight appr. 25-30g. Price $1/gr. Wishes Erich Haiderer