Latt,
I have not actually contacted the Cumberland City site yet, but may get to that today if I have time (after work). I just saw your post later yesterday evening and started looking into their location and tried to find out a little about them and found that information on the synthetic gypsum.
On that second link/article that I posted earlier (including again below)
ohioline.osu.edu/anr-fact/0020.html
It says this about the difference in gypsum used for drywall and agricultural uses:
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The final product is available for drywall manufacturing or for agricultural applications. To be acceptable for drywall manufacture, the material must have less than 600 parts per million (ppm) of total dissolved solids in the pore water, and a water content of less than 15% by weight. Material that does not meet these criteria is marketed as agricultural gypsum, and total dissolved solids is the major criterion for diverting material to agricultural uses. Power plant gypsum in Ohio is permitted as a fertilizer material through the Ohio Environmental Protection Agency, and is monitored by the Ohio Department of Agriculture for Ca and S contents.
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It sounds like to be used for drywall it has to be a little higher grade (more pure ?) and if it does not meet that grade then it can be sold as agricultural gypsum.
Here is map/image I found that shows location of the Cumberland City site and 11 other sites. Looks like there is one over in East TN and several up on the northern border of KY and a few in other States as well.
Steeltrap - looks like Classicfur fixed you up on Scotts Book - I have to agree with him it is a great read and covers all things ginseng and more.
Billy and Dieselrider are still around and posting just not quite as often here in the off season.
Thanks
TNhunter