Do you know what mills were served in this area, by these trains?  That will make a difference in whether it is natural ore or taconite pellets being transported.

 

US Steel didn’t have a sizable production capability of taconite pellets in 1957.  Their first true production plant didn’t come online until after the Taconite Amendment that Cyril mentioned in his reply.   In 1957 the primary Minnesota taconite plants were Reserve Mining, owned by Republic Steel and Armco Steel and Erie Mining Company, composed of Bethlehem Steel, Youngstown Sheet and Tube, Interlake Iron Co and the Steel Company of Canada.

 

In 1957, from Minnesota almost 62,000,000 tons of natural ore were shipped and only 6,348,000 tons of taconite concentrate (usually as pellets).   I think it is much more likely that your trains are hauling natural ore in 1957 (unless you can pinpoint the mill to one of the co-owners of Reserve or Erie).

 

Iron ore is classified by its chemical composition, and less by size of particle.  The mining companies were sometimes able to negotiate a premium for lump structure in the ore.  In 1957 about 65% of the iron ore was “direct shipping”, meaning that went directly from the ground to ore car to boat as rocks or dirt.  The remainder was concentrated in some manner to improve the percentage of iron.  Concentration generally resulted in some crushing into smaller pieces.  So you’ll probably see some variation in size from quite small up to 4” for concentrated ore and larger chunks for direct shipping.

 

I’d suggest a train have a mix of the different Scenic Express iron ore sizes to reflect the varied size nature, loading cars with different sizes.  However if you’re keeping the loads loose and loading and unloading the cars, pick one size – they’ll become mixed soon enough (I know this from experience).

-- Bob Hanmer