This is cultured marble unit, very common since the 70's. Some bathtub refinishers will still refinish those bowls, but many will not. My daughter bought a kit from Home Depot and touched up hers just so she could sell her condo. It didn't look great, but it passed inspection. These sinks tend to continue cracking. There is a new product called KwikBowl, where a sink is dropped inside the old sink. Kind of like a bathtub liner, but for a sink. Finished product looks like a new drop in sink.