Sodium Bentonite expands up to 15 times its volume when mixed with water. Calcium Bentonite does not. Sodium Bentonite is used by well drillers and stock pond construction folks because it will expand and create an impenetrable barrier.
You can put a tsp. of the unknown bentonite clay powder in water and add 5 tablespoons of water (that's 15 teaspoons of water giving you a 1:15 ratio) and leave it for a couple of hours and see what it does. If it only doubles its volume you have calcium bentonite and if it expands 10-15 times it is sodium bentonite.
I would not used sodium bentonite internally. I would think there would be a danger of getting an internal blockage.