Someone asked if you can burn coal in a regular fireplace. Here's what I found:
Hard coal doesn't burn well in open fireplaces, though some kinds of brown coal work OK. Any coal needs a lot of air under the fire in order to burn, so you need to use a grate compact enough to hold the coals. Try a small amount first and see how it goes.
For those who didn't know there was a difference in types of coal (ahem, me), brown coal is officially called Lignite coal and it has an inherently high moisture content. The hard coal I mentioned is Anthracite coal, a brittle black coal. It is what is usually used for residential heating (not in open fireplaces, though).
All clear now? Clear as coal anyway...