Mapp has a higher combustion temperature.
It is better than just propane, and better than butane by far. But, a decent oxygen setup is best. Whether its oxy acet, oxy propane, oxy and city gas, doesnt matter for gold, all are fine. Mapp is what I use for small amounts, and it works well if you have a bunch of insulation around it to trap the radiant heat in.
I think i spent 50 or 60 on my mapp setup.
As far as that bit of gold, there is a couple things you can do, depending on how bad you want it out.
Wait, and melt it when you have a proper torch
Or, you can remove it chemically from the dish with a bath in hot dilute nitric, which will eat the borax and liberate the gold. This is kind of a pain though, as the melt dish will soak up some of the nitric and water, and will break upon next use unless properly treated.
I usually let it dry for a few days in the sun, then on a hotplate for a few hours, under my heat gun for half an hour, then hit it with the torch, lightly. I start to add pinches of borax, which turn brown/black (im assuming from the nitric trapped in the pores of the dish), after so many small additions to the dish, it starts to clear up. I dump off any excess borax by tilting the crucible vertically and hitting it with a good strong flame, as you only want a very thin layer of borax when melting gold.
That can be used to clean up old grungy melt dishes, but, i now prefer to use alternating pinches of borax and soda ash to renew old and tired crucibles. I save all of the slag from these dish cleanings as it contains small prills of metal. One day I will melt them all and reclaim the metal.
