A Permonik Fey from Slovak folklore

The Permoník is a small mining spirit from Slovak folklore, said to dwell deep in the earth near rich veins of ore. He looks like a child-sized miner, with a dusty beard, a leather apron, and a tiny pickaxe. Though rarely seen, he knocks on rock to warn of danger or guide miners to treasure. When respected, he brings luck, but if angered, he causes tools to vanish or tunnels to collapse. Quiet offerings kept him friendly, deep in the dark where few dared linger.

Brought to my attention by @Appache