Originally posted by Byrd
They have solid geodes, actually (where the crystals fill up the hollow space.)

They sure do!, I have some of those..Some of them fall into the
agate category. This may be similar..

I'm still looking for that picture..I have a lot of pictures..LOL

Lightning strikes have been known, from what I understand, to melt beach sand into glass, quartz isn't a glass, but if you found something bizzare, like sio2 in wood, a tree getting blasted by a lightning bolt might explain it.