I was browsing some past pictures taken at a "trilladora de café" or coffee mill, and found this shot. I really like the contrast on this one, and also, the fact that it's the heart of the huge machine that selects the beans, it's a long process.
It all starts with the unselected beans that arrive in trucks from the farms, then the threshing machine peels the rind or shell off and selects the beans by size, color and quality (this last process sometimes is done manually by working ladies). This is where the richest coffee beans in the world come from, packed in sacs and exported all globally. My favorite coffee comes from this place too, Bohrcafé. Visit their site, they can send it to you in the US if you write to them at firstname.lastname@example.org