I went out back to make sure all of our gates were set for irrigation (they were) and Tom snagged me to 'help' him weigh all the rock he brought back.  My help <g> consisted of sitting on a chair in the shade with pad and paper (while he lugged the crates/buckets/bags/cobbles onto the scale) and recording the numbers. 

He had guesstimated that he schlepped back 1500# of rock (some inside the pick-up, some on the trailer with the quad) and turns out he was pretty close - the final total was a little over 1350!

He got some killer specimens which he will eventually transform into knife blades and arrowheads, and all it cost him was a couple hundred dollars in gas and a couple of knives in trade (while having a great time collecting it and visiting with all his rock buddies.)  He's way ahead of the game, with no shortage of materials.  Not that that was really ever a possibility...!