Sodium silicates are colorless glassy or crystalline solids, or white powders. Important polymer glasses include amorphous and glassy pharmaceutical compounds. Amorphous metal is a variety of alloys (e.g. Metglas) that are non-crystalline or glassy. By applying heat, they can be switched between amorphous (glassy) and crystalline states. Some materials, when rapidly cooled to a glassy amorphous state, have semiconducting properties. This produced several kilograms of clear, colorless vitric (glassy, non-crystalline) cuttings at the surface. The latter is characterized by silver and copper nanoparticles dispersed in the glassy glaze. Similar melting and cooling of silica occurs following lightning strikes, forming glassy lechatelierite. Crazing frequently precedes fracture in some glassy thermoplastic polymers. Doped/impure glassy carbon exhibited semiconductor phenomena. The matrix has numerous cracks filled with black glassy material. A hyaline substance is one with a glassy appearance. I see a glassy look coming over his eyes. It may have any texture from glassy to aphanitic to porphyritic. His public appearances were marked by his glassy eyes and slurred speech.