Let's talk dividends

I am interested in metals, being a mechanical engineer I understand that market, so I'd like to stick to what I know. Gold and Silver ETFs have given me decent returns, especially recently. But I want to expand into base metals as well as mining stocks. Most mining stocks go nowhere, despite movements in commodity prices. But their dividends are surprisingly juicy, or so I think. What dividend is considered good, as a percentage of stock price? 5%? 10%? 15%? Any difference in taxation compared to simple stock appreciation?