A gold prospector finds a solid rock that is composed solely of quartz and gold.The total mass and total volume of the rock are, respectively, 13.0 kg and 3.50 10-3 m3. The density of gold is 19 300 kg/m3, and the density of quartz is 2660 kg/m3. Use your answers to the Concept Questions and determine the mass mG of gold in the rock.