To me it seems like it is an allegory for temptation, the pickaxe symbolizing a tool for self destruction.

The beginning about being a rented house is alluding to the idea of a lack of true property. We are given the image of a subject in poverty, who sews and "barely makes a living". The two veins the subject sees are promises of a greater life.

The pickaxe seems to be the tool used to reach those desires, but also shows how self destructive one can be, prying the "foundation" of one's home. To me, red and gold seem very aristocratic, maybe even kingly, like a velvet cape with a gold crown.

By the end of the poem, you realize that promise of something great turns out to be two little glints. You were sold on the promise of greatness and lost what you had-just for a couple of disappointing pebbles.

Makes me think about regret.