Graphite, an allotrope of carbon, is not often described as a type of rock, and it does not always occur in rocks. However, as a member of the carbon family, it’s often found in certain types of sedimentary and metamorphic rocks. The two main types of graphite are flake graphite and hard (massive) graphite.
Flake graphite is the most commercially important form and is mined all around the world. It is found in the form of tiny flattened crystalline flakes or scales. It’s characterized by its grayish-black color and soft, greasy feel. It’s also relatively lightweight. Flake graphite can typically be found in sedimentary rocks that formed in an environment with a high organic content, such as shale and coal.
Hard (massive) graphite is much less common, but can sometimes be found in high-grade metamorphic rocks. It has a much higher density than flake graphite, and has a hard, black luster. It often forms in the form of veins running through the rock, and typically contains much more carbon than flake graphite.
Graphite is valued for many uses, including acting as a lubricant for machinery, for electrodes in batteries and for pencil leads. It’s also used in certain types of steel alloys and to coat the interior of certain types of industrial furnaces. Flake graphite is used in more industrial and consumer applications than hard (massive) graphite.
While graphite is usually associated with sedimentary and metamorphic rocks, it can also be produced artificially in a laboratory. This artificial graphite is produced by pyrolyzing (heating) hydrocarbons in a controlled manner. This process can provide a more consistent level of purity and strength than mines can achieve.
Graphite is an extremely abundant mineral, but it can be difficult to find in a usable form. Flake graphite is much more common than hard (massive) graphite, and is more economically feasible to extract due to its lower density. While graphite is often used to make pencils, it has many other uses as well, and is an incredibly versatile and valuable commodity.
Graphite is an important resource for many industries, and its abundance and affordability has made it accessible for a variety of uses. It is a versatile, abundant and accessible mineral, and can be found in sedimentary and metamorphic rocks around the world. Whether it’s hard (massive) graphite or flake graphite, it’s an extremely valuable and necessary ingredient for many applications.
