How many oxygen atoms are in 1.40 of quartz?
I know a blacksmith that does what william described. He takes the remnants out of their dumpster with permission and uses the larger ones for table tops.
Easy, Contact a shop that makes Kitchen Counters and other Quartz Marble and Granite items. You can find Them on line or in the Yellow Pages. They toss out a few ton's of what You are looking for every few weeks.In fact They have to pay to have it hauled away.