mattes

A decorative border around a picture used to inset and center the contents of a frame.

“The image is a perfect square of 8 cm (with white matte border the total dimensions are 14 cm tall by 11 cm wide).”

A background, often painted or created with computers

“Matte painting is a tool that filmmakers can use to create a scene that is impossible to achieve with conventional cinematographic means.”

(pyrometallurgy) The molten metal sulfide phases typically formed during smelting of copper, nickel, and other base metals.