Not that I know of - but there are two easy alternatives:
1. Cuttlebone - These are the bones of cuttlefish, and are normally sold in the "Bird" section of pet stores because people give them to their birds to wear down their beaks. If you wash it and then half-bury it in the gravel, the snails can come over and enjoy.
2. Those "weekend feeder" / "aqua-vitamin" pyramids. Those pyramids are made out of silicates and carbonates that slowly dissolve in the water, which can help the snails.
Either way - unless you're putting a Nerite snail in extremely soft water with a PH near 6 - they shouldn't have a problem. Just make sure that a little extra fish food gets their way (or hook them up with a bottom-feeder wafer every so often)