This is, admittedly, an unorthodox buy signal for the miners. It may turn out to be completely ridiculous for all I know.
Yet here it is. The green 13 DMA exited the bottom of the ribbon, in this case below the 400 DMA, and turned back inside the ribbon body.
On this chart it has done so previously, and when it did it was a good time to buy the miners. Play it again, Sam?

$HUI – Daily Moving Averages Ribbon