Garnet is a gem composed of silicate minerals, silicon oxides, there are many types of garnets. Garnets can be valuable. Garnets have been used as shot in place of musket balls in Alaska. Garnet has similar characteristics to gold flakes/nuggets, when run through a sluice box, packing up the riffles. To make gold sink when garnets are plentiful, miners use hydraulic riffles in place of regular riffles.