Rkeeb , you are right , it is tricky  to value mining company which is not producing yet, but Juniors are valued by their reserves.

“Reserves are evaluated through feasibility studies. These studies independently verify the worth of a deposit. A feasibility study takes the estimated size and grade of the deposit and balances it against the costs and difficulties of extracting it all. If the deposit will fetch more money on the market than it costs to dig up, then it is feasible.”

  So, market trade juniors according to all mentioned above data. Medium term investors unlike  Long term investors like to look at chart data. They not interested waiting few years for possibly big payoff ,  if they can make money now, and according to the chart SP is overbought – its time to sell make profit and move to next investment.

 There are plenty sites online which can help you to read basic chart. Chart is not a perfect tool but its useful one , it can tell investor when stock is overbought or undersold, different support levels ,resistance,  etc.

 Here is an example of one site: Investing 101: How To Read A Stock Chart For Beginners (moneyunder30.com)

 And of cause stock does moves on a News, positive or negative  . Right now we can use a good one.