A opossum is out in broad daylight, working at a patch of glare ice, and the poem simply watches it. The animal is digging for the scraps "we've pitched," meaning the food people have thrown away: old barbecue sauce, rotten cabbage. Nothing dramatic happens, but the scene is oddly tender and strange.
The speaker doesn't scold or pity the animal. Instead, the poem seems fascinated. The title, "Miner," turns the opossum into a worker tunnelling after something valuable, and our garbage becomes its ore. Then the last image shifts the mood: the opossum pushes its head into the ice as if breaking into "a great white egg." That suggests something fragile and new, as though the frozen ground might hold life inside it.
The mood is quiet, cold and attentive, with a hint of wonder. The poem also nudges us to notice what we throw away and who ends up depending on it.