Halite

Halite (rock salt) mineral Click on image for full size (138K JPG) Windows to the Universe/L.Gardiner

What’s that on your chips? It’s a mineral called halite! If you look closely at ordinary table salt, you will see that, just like other minerals, it looks like crystals. Halite is salt. In its natural form, it’s called rock salt.

Halite is found in sedimentary rocks. It is called an evaporite mineral because it formed in ancient seas and salt lakes as they slowly evaporated millions of years ago. As the water evaporated, thick deposits of salt were left behind. This process still goes on today. In fact, one way to get the halite used for table salt and road salt is to extract it from seawater by evaporating the water.

The sure way to determine if a mineral is halite is to taste it. However, don’t stick an unknown mineral sample in your mouth just in case it is poisonous. Instead, lick a finger and rub it against the mineral specimen that you think is halite. Then taste your finger so you don’t get too much of the mineral into your mouth.

• Shape: Isometric (crystals usually look like cubes)
• Luster: Glassy
• Color: Clear, white, pinkish, or gray
• Streak: White
• Hardness: 2.5 on Mohs Hardness Scale
• Cleavage: 3 planes of perfect cleavage
• Fracture: Conchoidal