Black rock salt can have several explanations depending on the context. Here are a few possibilities:
1. **Purity and Impurities**: Some types of rock salt can contain impurities, which may give them a darker color. These impurities can be from minerals or other natural elements present in the salt deposits.
2. **Himalayan Black Salt**: If you're referring to black salt used in cooking, it might be Himalayan black salt (kala namak). This salt