The term 'Brittle Nonmetallic Element' refers to Silicon, which is a chemical element with the symbol Si and atomic number 14. It is a hard and brittle crystalline solid with a blue-gray metallic luster; it is a tetravalent metalloid and semiconductor. Silicon is the second most abundant element in the Earth's crust, making up 25.7% of the crust by mass. It is found in many minerals, including quartz, feldspar, mica, and talc. Silicon is an important component of many materials, such as silicate minerals, clays, and glass.