Eventually the concentration is so great that crystals of borax and other boron minerals form and accumulate to great thickness. Kernite is found at the bottom of these deposits in stratified units with some kernite crystal layers growing several feet thick. Individual crystals can be quite transparent and appear similar to certain gypsum crystals. However, kernite is harder and forms splintery cleavage fragments. Specimens of kernite are interesting, and can make a good addition to one's collection.
Color is white or gray to colorless.
Luster is vitreous to greasy. Transparency crystals are transparent to translucent. Cleavage is perfect in two directions forming splintery fragments. Fracture is splintery due to cleavage. Streak is white.