For the sake of the exercise I’ll assume for now that an intermediate is in for the GDX. To locate a target take the Fib swing through the 18.58 low and 25.58 high and project from the current low. The 1:1 ratio hits around 25.1 and the 1.618 extension hits at 29.7. Now use a schiff pitchfork from the major low as shown. There is a 80% chance of hitting the red median line if the current low holds. The point of intersection is 29.7 in April

Note that the current low is below 18.58 so it is better generally to locate stocks which did not make a lower low in this period since it suggests relative strength. EXK is an example of this.