Weighted pewter should say "weighted" someplace, often in really small print. Common for candle sticks, and stuff is like a horse hoof glue, or petrified Yak excrement. Hard as a rock, often hard to peel the pewter off of and man you can almost throw out the pan if any of that stuff gets melted in it. Or maybe set it on a bon fire of pallets. Stuff is really hard to clean out once it gets melted. Plus the pewter covering it is as thin as aluminum foil. Heavy duty aluminum foil but still pretty thin.
You should be able to gouge pewter with a thumbnail (on the back where it won't show) I have every so often found a picture frame or other small item that isn't stamped pewter but is a tin/pewter alloy of some sort. If it is cheap enough I'll give it a shot, I can gamble $2 on possibly getting a pound of pewter, or just another knick knack. More and more I am seeing picture frames that look exactly like pewter on the front BUT are a rough texture on the back and too hard to even mark with a finger nail. If it doesn't say pewter it is a gamble, now if you are buying $60 worth you don't want it to be "might be" pewter. But a couple of $1 picture frames at Salvation Army? Sure, why not. Either a good find or a cheap chance to educate yourself on what not to buy.
I should mention that really large metal tray that once I was "sure" was pewter wouldn't melt when hit with a propane torch, can't bend it, and won't scratch so to this day I dry tumble lube bullets on it covered with wax paper.
Has been said before but bears repeating. Take the time to determine if any of that stuff has collector value before making it a puddle. Lot of places over price pewter but some pieces do have a high value. Black pewter (has lead content so ages to a more black color) is usually from the 70's or before. Worth a quick check of prices for sold ones like it on eBay or look up the pewter mark online.