Juniors and majors are usually the two sizes mining companies come in.
Small exploration firms that search for new deposits are usually Junior miners who don’t normally fully develop the mine alone. The primary business of the major miners is bulk mining that sell on the mineral deposits they develop on the open market; they also do some exploration.
Major and junior miners will partner together when majors are looking for more deposits and/or the juniors who have proven reserves are looking for capital for further development.

The most volatile mining stocks, that can be extremely profitable under the right conditions, are the Junior mining companies. There is the downside of volatility and investing in the mining sector has more risk of course than investing in physical precious metals. With that said senior mining stocks are usually more liquid and their prices seem to be less volatile and are usually perceived to be less risky than junior mining companies.

Mining stocks ETF’s allow investors to gain exposure instantly to a mini-portfolio of precious metals mining companies. Some benefits may be savings on fees and commissions, having tax advantages and making it easier to invest in the precious metals mining sector.