No, rock salt is not purified.
Rock salt, as it's mined, retains natural impurities because it does not undergo any kind of chemical purification. These impurities generally constitute a small percentage (a few %) of insoluble matter, primarily calcium sulfate, also known as gypsum. This means that rock salt you find will contain other minerals and elements present in the environment where it formed.
Here's a table summarizing the key characteristics of rock salt:
| Feature | Description |
|---|---|
| Purification | None |
| Impurities | Contains natural impurities present in the mineral itself. |
| Common Impurity | Calcium sulfate (Gypsum) |
| Impurity Amount | Typically a few % of insoluble matter. |
Therefore, when using rock salt, especially in applications where purity is important, it's important to consider the presence of these natural impurities.
