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[quote user="tiskilwa"]When I worked at a port on the West coast, a ship that visited frequently was a bulk gypsum carrier.  It brought the stuff up from Mexico (I believe), and discharged it to a large cement plant at this particular U.S. port. The question I have is, does much gypsum go by rail in the U.S., either imported by ship or mined in domestic quarries?  It's something I've never read or heard a thing about.  Just curious. Thank you. [/quote] Raw gypsum is too low in value  (average FOB mine price in the U.S. for crude ore, 2005, $7.31/metric ton) and too widely dispersed in its sources to tolerate rail shipment, unlike, for instance, low-sulfur coal, which is highly localized in its occurance.  Typically the wallboard and plaster plant is built as close as possible to the mouth of the mine.  The major shipment of crude gypsum by rail is to cement plants, where it is blended with portland cement typically 2% to 6% by weight to retard the cement's setting time, and as a soil conditioning agent.  There are also a few private mine railways that ship raw gypsum from a mine to a calcining and wallboard plant, notably the 20.5 mile U.S. Gypsum narrow-gauge railway serving that company's wallboard plant at Plaster City, California.  Curiously, synthetic gypsum is produced as a byproduct of a number of industrial processes including  sugar beets, electric power plant acid rain neutralization, and titanium dioxide production, and 8.7 million metric tons of this was sold to wallboard plants last year.  A substantial quantity of synthetic gypsum called phosphogypsum was produced as a byproduct of phospate fertilizer production, but this cannot be used for wallboard because it contains radionuclides and emits radon gas (phosphate ore commonly contains trace amounts of uranium, radium, etc.) Total use of uncalcined gypsum in the U.S. was 3.1 million metric tons for portland cement in 2004, and 1.03 for agriculture and miscellaneous.  I don't know how much of this moved by rail but it probably was substantial.  But it was dwarfed by the 30.4 million metric tons that was consumed by wallboard and plaster, almost none of which moved by rail in the raw form.  1/2" wallboard costs about $1100 per metric ton, and given that value and its weight it easily moves by rail if the line-haul from plant to consumption point is 300 miles or greater. S. Hadid
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