Physical Characteristics of Montmorillonite

Color is usually white, gray or pink with tints of yellow or green. 

It is never found in large individual crystals, usually found in compact or lamellar masses and also seen as inclusions in quartz as fibers and powder-like masses. 

Cleavage is perfect in one direction, basal and not seen in massive specimens. 

Hardness is 1-2 in Mohs scale (can sometimes leave marks on paper). 

Crystals expand to many times their original volume when added to water. 

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