2012-4-17 · Calcium Bentonite Processing Plant. April 17, 2012 - PRLog -- Bentonite is a smectite clay formed from the alteration of siliceous, glass-rich volcanic rocks such as tuffs and ash deposits. The major mineral in bentonite is montmorillonite, a hydrated sodium, calcium, magnesium, aluminum silicate. The sodium, calcium, and magnesium cations are ...