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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?

Specimen 1

Specimen 2

Thanks for your help!

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    $\begingroup$ See this guide for ideas for more detail that you can add. $\endgroup$ – naught101 Sep 8 '14 at 6:40
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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?

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  • $\begingroup$ i.imgur.com/d5Q30Lj.jpg $\endgroup$ – user748 Aug 6 '14 at 23:25
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    $\begingroup$ I also found this specimen around the same area. It seems more like lignite to me. The former specimen is much smoother to the touch and lighter in weight. i.imgur.com/5FHU1wa.jpg $\endgroup$ – user748 Aug 6 '14 at 23:33
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    $\begingroup$ Have in mind that anthracite takes more time ( is the most metamorphosed type of coal, but still represents low-grade metamorphism), in which the carbon to for from lignite. So, unless you have a transfer part from somewhere else, the formation are too young for anthracite $\endgroup$ – Vasileios Antoniou Aug 8 '14 at 21:45

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