D&RGW boxcar question

In working on D&RGW 3038 today, I found a lot of evidence that the car was once set up to carry bulk qauntities of a fine white powder(gypsum?); the floor had areas where it had been covered with paper to seal cracks, the walls had evidence of being sealed with paper(lots of staples, staple holes and scraps of paper), the door openings had the remians of steel strapping (which would have been used to secure heavy cardboard across the door openings) and the floor was coverd with lots of fine white powder. The car also had the remains of the wood "placards" that the Rio Grande would put next to the doors to denote special assignments.
Does anyone know what this car was carrying and to where? It looks like it carried more than once.
Jason Midyette