Sujata Nutri Pharma is one of the leading manufacturers and exporters of Calcium carbonate CAS no. 471-34-1.

CaCO3 occurs naturally as the principal constituent of limestone, marble, and chalk, which can be prepared by the precipitation from dissolved calcium hydroxide and carbon dioxide.

Calcium carbonate can be used as a precursor to prepare Pd/CaCO3, which can be used as a catalyst:
In Miyaura-Suzuki cross-coupling reactions.
In the ligand-free Stille cross-coupling reaction between aryl halides and tributylphenyltin to synthesize biphenyls.
It can also be used as a base in the Pd-catalyzed regioselective Heck reaction of fluorinated haloaryls with olefins to synthesize substituted olefins.