Granite Block

Both the elemental and the golem in granite caves drop it, and a Granite Golem statue keeps producing them indefinitely. Wire one up and you have unlimited granite without ever walking back down to the cave. Anything built out of it inherits that, which is unusual for a decorative stone.

The raw block is close to worthless at a shop. Smoothing it at a bench costs nothing and loses nothing, and the smooth version plus a handful of Torches makes Granite Candelabras, which sell for a real amount each. Crafting the torches instead of buying them widens the margin further. With a statue feeding it, the input is free, which makes this one of the better passive money loops in the middle of a run.

What the game draws is not typical granite. The dark blue shimmer matches larvikite, sold commercially as blue pearl granite, which is a different rock entirely despite the trade name.