Took a flyer & sold some Feb GDX 42 puts. I got 1.48 for a promise to buy GDX at 42 by Feb 19. In order to lose on this, GDX must be lower than 40.52 before then.
The basic strategy is to sell near-the-money short term puts on oversold stocks (GDX is near RSI 30 right now). This system works if there is any small bounce or even a stop in the decline. This has worked well for me over the years, but was a disaster in 08 when the market crashed. So it's best not to try this before a market crash, lol.