Assuming you can recover ALL of the gold in the ore- 100 grams of sylvanite would contain 28 grams of gold. 70 divided by 28= 2.5, so 2.5x100= 250 grams of sylvanite.

332.143 grams of gold

The principal ores are calaverite, a telluride (containing tellurium) containing 40 percent gold, and sylvanite, a mixture containing 28 percent gold

Gold generally exist in nature as a pure metal; several gold minerals (without industrial importance) are săcărîmbit, sylvanite, krennerite, calaverite, petzite.

Gold generally exist in nature as a pure metal; several gold minerals (without industrial importance) are săcărîmbit, sylvanite, krennerite, calaverite, petzite.