Table salt or sodium chloride is one of the most commonly used minerals in our lives. We like to add it to our food to add flavor and iodized salt is key to the healthy development of our nervous system.
Since salt has a crystal structure it has regular shapes in the microscopic scale. This explains the cubical shape of some of the salt particles. While store-bought salt has a cubical shape in the microscopic scale if the salt is kept in a salt shaker for an extended amount of time salt particles become rounded. This is because of the mechanical wearing of the particles inside the shaker.