Calcariferous is an uncommon word, but there are several synonyms that can be used to convey a similar meaning. One option is calcareous, which refers to something that contains or is made up of calcium carbonate. Another possible synonym is chalky, which describes something that is white and powdery like chalk. Limestone is also a synonym for calcariferous, which refers to a type of rock formed from calcium carbonate deposits. Lastly, you could use the term carbonate to describe something that contains this compound, which is often found in rocks, shells, and other natural substances.