Clay minerals typically form over long periods of time from the gradual chemical weathering of rocks, usually silicate-bearing, by low concentrations of carbonic acid and other diluted solvents. 
Bentonite clay also called Montmorillonite, is a very popular healing clay that also cleanses the body. This clay is made from minerals such as iron, sodium, calcium, potassium and magnesium, formed from volcanic ash. The name of the clay (bentonite) comes from the biggest deposit of Bentonite clay that is located in Fort Benton, Wyoming.
Adding water to the clay gives it a negative electric charge, which in turn, removes toxins from the body. It works both externally and internally. 
Clay works both internally and topically to help detox and clarify. If you desire clear, fresh and vital skin, here are a few reasons why you should try a bentonite clay face mask!
Some Benefits of Bentonite Clay:
Clay unclogs the skin pores and shrinks them
Clay helps control the overproduction of sebum
Clay draws out the toxins from the skin
Clay makes skin softer
Clay gives a definite glow to your face
Clay exfoliates
Clay helps reduce the appearance of scars
Clay is safe for all skin types
Clay can be used to regenerate skin tissue
Clay gives you an even skin tone
Clay can be used in place of toxic face powder
 
Other Uses of Bentonite Clay
Detoxifying bath – Add ¼ cup of clay to your bath water along with some lavender essential oil for a relaxing and detoxifying bath that will leave your skin smooth and refreshed
Toothpaste – Mix a little clay with your regular toothpaste. The clay will help draw toxins out of your oral cavity. You can even mix ½ teaspoon of clay in with a 1/4 cup of water and use as a rinse to draw impurities from your mouth.
Baby powder – To ease the soreness and inflammation of a rash, sprinkle a little clay on your baby. You can also mix some clay with a little water to form a healing mask for the sore area.
Fight off morning sickness – Pregnant women who find themselves a bit queasy may get relief when they take ½ teaspoon of clay in water a couple times a day.
 
Caution: If you react to some metals or have an allergy to some substances in the clay, you may experience itchiness on the skin. It is rarely seen with topical use of bentonite clay on the skin unless you have super sensitive skin. Test the clay on less sensitive areas of your body before using on the face.