Polysilicon is distinct from monocrystalline silicon and amorphous silicon. Cellulose consists of fibrils with crystalline and amorphous regions. Textile fibers are a mixture of crystalline and amorphous substances. Boron is known in several crystalline and amorphous forms. It is usually weathered limestone mixed with diatomaceous, amorphous, or crystalline silica. Tellurium has two allotropes, crystalline and amorphous. These allotropes are known as the amorphous and the crystalline allotropes. They are hydrated and act as either amorphous or crystalline. Some thermoplastics may be fully amorphous, while others have a partially crystalline/partially amorphous structure. It is an impure form of polycrystalline diamond consisting of diamond, graphite, and amorphous carbon. Certain places became less crystalline and more amorphous. Important polymer glasses include amorphous and glassy pharmaceutical compounds. With the exception of amorphous silicon, most commercially established PV technologies use toxic heavy metals. Some polymers retain such a disordered structure upon freezing and readily convert into amorphous solids. Some materials, when rapidly cooled to a glassy amorphous state, have semiconducting properties.