Palygorskite is often classified as a clay mineral because it is present in some soils and behaves like many other clay minerals. Unlike most other clay minerals, palygorskite can form large crystals. Palygorskite is found in hydrothermal deposits, soils and along faults often lining the slicken sides of fault lines. Color is white, gray pale lavender. Luster is silky to dull.
Crystals are transparent to translucent.
Cleavage is perfect in one direction producing thin sheets or flakes. Fracture is not readily observed due to cleavage, but is uneven. Hardness is less than 2. Streak is white. Thin crystal sheets are flexible.