A street plate may be used to identify the mineral property of hardness. Hardness is a key mineral property and is determined by a mineral's ability to resist scratching or being scratched by another material. The street plate, usually made of a hard and durable material such as steel, is often used as a standard for comparison when determining the hardness of other minerals. By observing whether a mineral can scratch, be scratched by, or leave a mark on the street plate, geologists or mineralogists can determine the relative hardness of the mineral and categorize it according to the Mohs scale of mineral hardness.
