In India during 1960-61, while inspecting the dolomite and
white clay mines at some part of South India, Rajasthan and Gujarat
for the first time doubted some white clay or dolomitic chalk
material as Barite and got the sample tested, on testing, properties
of this doubted material turned out to be Bentonite clay.
Considering the importance of this clay, the Directorate of Geology
and Mining during field season in 1963-64, 1964-65 and 1969-70, took
up a detailed survey work. After knowing constituents and structure
of this clay, a detail study has been carried out by Directorate of
the Petrography and Mineral Chemistry Laboratory on few samples from
the area surveyed.
Bentonite is absorbent clay consisting mostly of the mineral
montmorillonite. It is formed by the weathering of volcanic ash,
most often in the presence of water. Chemically, it is an impure
form of hydrated aluminum silicate. The formula of montmorillonite
may be written as (Na,Ca)0.33(Al,Mg)2Si4O10(OH)2•(H2O)n. There are
two types of Bentonite: sodium Bentonite, also called swelling
Bentonite and calcium Bentonite, also called non-swelling Bentonite.
Bentonite is useful for a wide range of applications such as sodium
Bentonite is used in drilling mud for oil and gas wells, foundry,
palletizing, piling, cosmetics, fertilizers, pesticides, sealing
subsurface disposal systems and in preventing metal pollutants from
entering groundwater. Wide use of Calcium Bentonite is in the field
of Bleaching clay, pet litter, as an agent that cleanses the
intestinal tract, therapeutic face packs. In addition, Bentonite is
used in ceramic structures, pyrotechnics etc.