Thanks for all the suggestions, I tried several but this Virginia USA coal was only about another week from being compressed into diamonds when it was mined. As mentioned earlier, hitting it hard enough to break it made a mess.
So I wandered though our local chain giant 'Hobby Lobby" (mostly crafts for the ladies) and found the suggested canvas pouch for less than a quid. (Note the coal bucket in the background; I did more damage to bucket than I did to the 1000 carat coal lumps.)
Starting with a full lump, I went through several squeeze cycles:
I then sorted the chunks though a 4" diameter 'training' sieve (from Amazon, about 5 quid, they called it a 'training sieve' because of the large number of complaints bout the 'uselessly small size'). I had to put an finely crafted extension on the sides to keep the coal in the sieve during vigorous shaking:
The result was three grades -
Fines - engine house ballast
Medium - a little small but useable
Larger - a bit larger than ideal but still useable:
By the time I crushed the coal shown above plus one more round, the bag became divinely holy. Since all my tenders have a platform for the coal, I have a decent supply for the time being. Maybe I will lay on a few more canvas bags while they are available, a buck twenty-nine plus 7% tax fits the coal crushing budget - and I end up with genuine 1:24 scale Chesapeake and Ohio coal!