Iron ore cars and load | ModelRailroadForums.com
Yep, definately sounds like a taconite pellet. Note that while coal or other commodities generally wouldn't be ever moved in a small ore car, due to the size not allowing much of a load of light coal per car, ore pellets could sometimes be loaded in a regular hopper on some (especially eastern) roads that didn't operate the little 1-bay ore "jennies", although it would only have a small amount ...