Thanks. I did have that record saved in my Ancestry.com shoebox, just in case. It's so hard--there's no way to prove it's him. But it is close, and I've found spelling and transcription errors on a lot of censuses. I'd really like to find a death or burial record, but after that 1840 census, there's nothing. There's a Joseph Peatfield who was naturalized in the Essex County Court of Common Pleas 1840, but I suspect that is his son, who was living there at the time. No newspaper articles about the coal mines. I don't know which ones he was involved with, or how. All I know is that he "invested in coal lands" and "died at a ripe old age". He would have been 68 years old in 1840.
Thanks for the information. I'm going to find him some day!