Rock salt, also known as halite, has a vitreous luster, which means it has a glassy or shiny appearance.

Here's why:

* Crystalline structure: Halite is a crystalline mineral, meaning it has a regular, repeating arrangement of atoms. This structure allows for smooth, flat surfaces that reflect light.

* Transparency: While rock salt is often translucent, it can also be transparent in its purest form. This transparency contributes to its glassy appearance.

However, rock salt can sometimes appear dull or earthy due to impurities or weathering.