Carbon has numerous physical properties, and some of these properties are quite different depending on the structural form of the molecules. Carbon's mineral hardness is measured at 0.5 for graphite and 10.0 for diamonds. Some of the properties unique to carbon elements include extremely high melting points, such as 6400 degrees Fahrenheit, and boiling points, such as 7281 degrees Fahrenheit. At room temperature, carbon is found in a solid state.
Carbon is classified as a nonmetal. Carbon is highly transparent in its diamond form, and it is opaque and black as graphite. As a diamond, carbon is one of the hardest known substances, while the graphite form of carbon is much softer. Diamonds are barely electrically conductive, while graphite is an excellent conductor. Carbon in any form is very brittle and cannot be rolled into wires or pounded into sheets. The element forms a diagonal lattice structure and hexagonal crystal structure.
The physical properties of an element are those characteristics that can be observed without changing the substance into another substance. Physical properties are usually those that can be observed using the five senses. Such observable properties include color, luster, freezing point, boiling point, melting point, density, hardness and odor.