--- In STMFC@yahoogroups.com, water.kresse@... wrote:
denser materials such as gypsum for making cement. The gypsum
staining is why the C&O eventually changed over to gray from black
Ft Dodge Iowa is/was one of the largest producer/miner of Gypsum. The
stuff sold to cement plants was on 2" (+ -) chunks deliverd in open
hoppers throughout the Midwest.
Differences in parts of the country?