We're after pure gold, but rock that contains gold also includes lots of other materials such as quartz, calcite, and the sulfides of other metals. Since we need to separate the gold from the rest ...

He uncovered a heavy, reddish rock weighing almost 18 kilograms (40 pounds). Believing it might contain a valuable nugget of gold, he took the rock home with high hopes. Determined to reveal its ...

We're after pure gold, but rock that contains gold also includes lots of other materials such as quartz, calcite, and the sulfides of other metals. Since we need to separate the gold from the rest ...