I can understand if there would even be a deposit charge provided to the stone carver/miner. As such, I suppose it's fine in theory to have something like marble or obsidian statue checking/savings accounts. However, I'm not sure that stone brokers would buy it. What do you think?
Cuniform is a very outdated method of handling things, and verification systems would be troublesome. Electronical databases work well enough, and so does physical bartering.