Ember
ember cinder ash clinker coal
Another name for anthracite coal is hard coal.
Bituminous coal, or soft coal
It is sometimes called a diamond - as in the suit in playing cards, not a jumped-up piece of coal!
Vein and/or Peat (depending on reference, peat is the beginning form of coal).
Anthracite coal.
scuttle
Another name for coal is "black gold." This nickname reflects its value as a source of energy and its dark color.
Other names for coal include anthracite, bituminous coal, lignite, and thermal coal.
A lump of coal is also known as a coal nugget or coal chunk.
Coal. Carbonado
rhombus, quadrilateral.