The miner is a background character in the Gravity Falls series.
The miner makes his first appearance at the grand unveiling of Wax Stan in "Headhunters" and is, like the other attendees, disappointed and angered with Stan for lying about the free pizza. Later, he attempts to enter Skull Fracture, but the bouncer denies him entry, stating that the facility does not serve miners. The miner leaves angerily.
From what little we've seen of him, we can assume he's a fairly sociable fellow, coming to events like the Mystery Fair, and Pioneer Day. It can be inferred that he does enjoy a stiff drink from time to time, however, as he did wish to enter the Skull Fracture bar.
His appearance is very much that of a typical miner, wearing a lamp-light helmet and carrying a pick-axe. He has a scruffy, black beard, and a dirty orange jumpsuit. As one might expect, because of his profession, he has dirt and dust all over his body and clothing, some of it even having made a visible swathe of grey in his beard.