What type of glass is known for being unable to be cut or broken using conventional tools?

Lexan is a brand name for polycarbonate, which is a type of thermoplastic. It is known for its remarkable strength, impact resistance, and flexibility. Unlike conventional glass, Lexan is not only difficult to cut but also exceptionally tough to break using standard tools. This makes it ideal for application in environments where safety and durability are paramount, such as in security glazing and protective eyewear.

Tempered glass is designed to be stronger than regular glass, and while it can resist impacts, it can still be shattered and is often cut under precise conditions. Laminated glass, which consists of layers of glass with an interlayer, holds together even when shattered but can be cut using specialized techniques. Cylindrical glass refers to the shape rather than a specific property, and does not inherently offer the qualities of impact resistance attributed to Lexan.