Well, one of the things that used to come by rail - maybe the largest amount - was ground feldspar from Amco GA. N&W or SOU covered hoppers. I'm told that mineral reserve is worked out. Also used to get Feldspar from Pacer Corp in Custer SD. Tracks were removed from Custer probably 20 years ago. I think I heard the feldspar now comes from Germany. Gonna have a tough time getting that on rail.
Another thing that used to come in was powdered alumina. IIRC, the price of the material itself was very high. Once VI started the ability to receive by truck, they were buying in small quantities and didn't have to front the $$$ for a whole carload.
Actually the beginning of the end was the Conrail split. Before that, everything came by rail. When the meltdown in service happened the plant was in danger of shut-down account running out of materials. In desperation they brought in a bulk truck, bought some extra lengths of flexible hose, cobbed a way to get from the truck to the silo, and disaster was averted. And guess what - once the hose was set up, and routed to the appropriate silo, the TRUCK DRIVER was the only guy unloading - no more paying a VI guy to poke poles into the hopper cars all day, no more clumped up clay from leaking hatch covers, no more product spilled on the ground when a pocket slide didn't fit right.
As an indication of what used to be, in 1980 VI took an even 200 cars.
In 1985 they received 103.
In 1995, the railroad handled 126 cars for the year and 112 of those were for the insulator plant.
A while back I spoke to someone, can't recall who - might have been a VI person, may have been a railroad employee - who said the plant gets about 2 cars a month now. I have no idea how accurate that is, but I have driven by the place a few times recently and in each case there were either one, or no, cars at the spot.
Time is running out.