Sounds like it has the same mantle as a presureized camp lantern.. If so
you can get them from Coleman or any other camping supply place.

I also have one that use these that screws onto a small propane cylinder.

What ever the type, if they use pressure tank they always seem to use the
same mantle and put out a lot of lite. However they are noisy and generate
more heat than you want to deal with in summer.