I found a piece of (what I believe is) coal, on Cape Cod last week. Its density is 1.43 grams per milliliter. With this information is it possible to know whether it's Anthracite, Bituminous or Subbituminous?
Thanks for your help!
Generally you can't say what type of coal only by density (also, I don't know how you measured it and how accurate this measurement was). Anthracite differs from ordinary bituminous coal by its greater hardness, its higher relative density and luster which is often semi-metallic. By looking the geological map of the area, you can see some lacustrine deposits (lake). It is very likely to find coal in these deposits and judging by the age of formation, I think is more like you have found lignite. Can you describe colour of the specimen you found or any other information about the structure, texture?