This is a small jar of anthracite coal, No. 4 sort, from Pennsylvania.
There is approximately 0.62 to 0.66 pound (280 to 300 grams) of coal inside the jar. There will be some slight variation from jar to jar.
Anthracite coal, or hard coal, has the highest carbon content, the greatest hardness, and the fewest impurities.
This is "No. 4 coal". No. 4 is a measurement of size, not content. The standard sizing of No. 4 coal is 3/64 to 3/32 inches (1.19 to 2.38 millimeters). Some random pieces measured 0.31 inches (8 millimeters).
The No. 4 is fine coal that can be used for water filtration and waste water treatment.