A 8.35 kg mixed-mineral sample contains chromite (FeCr2O4) as the only chromium-bearing ore. The sample is subjected to an industrial process, using a ferrosilicon alloy as a reducing agent, which quantitatively converts all of the chromium into 12.6 kg of a ferrochrome alloy (stainless steel) which is 15.8% Cr by mass. What is the percentage of chromite (FeCr2O4) in the original sample?