http://lists.railfan.net/erielackphoto.cgi?erielack-08-07-16/B0798.jpg et seq.

This image plus the few after this one show a LARGE number of steam era freight cars in 1911, way before the transition era, but still very interesting.  Since these are glass plate negatives, the resolution is quite sharp even when zoomed way in.

Check out the loads in both the open topped cars and the hoppers.  Not all coal is the same, even in two cars coupled together.  All the coal you see, though, is most likely Anthracite, just in different sizes.

Enjoy!

Schuyler