This is important to farmers with extended dry periods, engineers of earthen dams or levees or perhaps to plug up old drill holes to prevent leakage of toxic fluids from bottom levels to higher aquifers used for drinking water. As a mineral specimen, montmorillonite does not get much consideration. Usually, pure samples of montmorillonite are massive, dull and not very attractive. However, as with all minerals, there are those exceptional specimens that defy the norm. Montmorillonite has been found as attractive pink inclusions in quartz crystals, and these make for interesting specimens.
Color is usually white, gray or pink with tints of yellow or green.
Luster is dull. Transparency crystals are translucent and masses are opaque. Also seen as inclusions in quartz as fibers and powder-like masses. Fracture is uneven to lamellar. Streak is white.