Strange Lightweight 1974 Quarter

Hmmm? The reverse looks similar to that of coins struck on Foreign planchets. The letters look somewhat to fade into the rims, having been struck on a smaller Foreign planchet. The copper edge is throwing me off for some reason.
I think liveandievarieties is perhaps correct. May just be thin stock, accounting for the full gram weight difference.

I too have one of those quarters! I received it just today. It does make a strange sound. I noticed it immediately when I dropped it into my coin purse after receiving it as change. It is about half the thickness or a little more then a normal quarter. It has the copper as you can see on the sides. This coin has seen better days. It was pretty tarnished when I got it. I was able to clean it some but I suspect that the damage it has is permanent. Still I would like to know what one in poor condition would be worth if anything more then a quarter. Should I hold onto it to pass on to my grandchildren? Any help appreciated.

The most prosaic and most likely explanation is that the coin was struck on a planchet punched out of rolled-thin stock.

I have one similar, but you cant see any copper on mineand better condition.