Lower selling costs decrease Mosaic's revenue flow and negatively impact business financials. Mosaic's gross margin for the third quarter of FY 2010 was 28% of net sales, a figure offset by selling prices that were approximately $200 per tonne less than sales prices a year ago across all segments. In the third quarter of this year, Mosaic sold 2.5 million tonnes of phosphate as well 1.9 million tonnes of potash for approximately $800 million lost this past quarter as a result of lower sales costs.