Aragonite turning into Calcite

Aragonite is something that grows on different rocks such as quartz, limestone (which could be a new block), and even seashells of various creatures. If there were hermit crabs you could add the aragonite to the shells over time (like how copper oxidizes) and be able to have a renewable source of calcite. Limestone is just a sedimentary rock that's been formed under a lot of pressure so it could be another new block where deepslate is.