No kidding a tad high!
There must be something wrong with my Colorado geography - I wouldn't consider those 2 locations a hop skip jump apart. Wouldn't Denver be a lot closer?
Gypsum is usually considered a soil amendment (calcium) but the pelletized stuff apparently is used for breaking up clay soils. But, like perlite, its processed so more expensive. Have you considered ground up pumice or lava rock? I can go down to the local rock/dirt place and buy it by the yard in CA.
