The Epithermal Gold-Silver Deposit has ore sizes ranging from tens of thousands to over a billion tons, gold grades from 0. 1 to over 30 grams per tonne and silver grades from less than 1 to thousands of grams per tonne. There is a grade of Historically, these deposits have been important sources of gold and silver and are estimated to contain about 8 of the world's gold. The wide range of tonnage grade properties makes epithermal gold and silver deposits attractive targets for exploration and mining companies large and small.br br br .