Show gypsum the rock that makes plaster of paris was mined in the united states in 1913 to the extent of short tons an increase of tons over the production of 1912 according to R W stone of the united states geological survey the total value of gypsum and gypsum products produced in 1913 was compared with in 1912 an increase of gypsum sold crude without calci ning and used principally as an ingredient in portland cement and paint and as land plaster amounted to short tons valued at which is a good increase over the business of 1912 about 85 per cent of the gypsum sold crude in 1913 was used for portland cement at an average value of a ton the quantity sold for this purpose is steadily increasing the quantity of gypsum sold crude for land plaster has remained nearly stationary for four years but the average price dropped in 1913 from to a ton |