What kind of car was used? I am referring to bulk sand from a pit that ships out sand and gravel. Perhaps this sand would not be that specialized. Wouldn't it need to be protected from the weather? On a side note, In the early 1970s (long after covered hoppers became popular) I remember a tower operator referring to an ancient gondola in a consist loaded with sand. I did not see it and wondered if it was covered.

Victor A. Baird
http://www.erstwhilepublications.com