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. Associated Minerals include other clays , garnets , biotite and quartz . Best Field Indicators softness, color, soapy feel, luster and expandability when added to water.