What material is the glass in a CRT typically made of?

The glass used in a cathode ray tube (CRT) is typically made of mineral glass. Mineral glass is a composition that includes silica and various other minerals to enhance its optical clarity and strength. This type of glass is particularly suitable for CRTs because it can withstand the high vacuum created inside the tube and provide the necessary durability and electrical insulation. Its properties allow for effective image display while being robust enough to handle the stresses of operation.

The other materials mentioned, such as plastic, tempered glass, and borosilicate glass, do not possess the same combination of properties needed for the specific applications of a CRT. Plastic would not be suitable due to its tendency to warp under heat or pressure, while tempered glass, although strong, does not provide the necessary electrical insulation. Borosilicate glass, known for its thermal resistance, is not typically utilized in CRT applications where the specific characteristics of mineral glass are required.