The principal types of natural graphite, each occurring in different types of ore deposits are:
There are three distinct types of natural graphite which occur in different kinds of ore deposits:
- Flake Graphite
- Less common form of graphite
- Carbon range of 85-98%.
- Priced ~4X higher than amorphous graphite
- Used in many traditional applications
- Desirable for emerging technology graphite applications (e.g. Li-ion battery anode material)
- Crystalline small flakes of graphite (or flake graphite) occurs as isolated, flat, plate-like particles with hexagonal edges if unbroken.
- When broken the edges can be irregular or angular;
- Amorphous Graphite
- Most abundant form of graphite
- Comparatively low carbon content of 70-80%
- No visible crystallinity
- Lowest purity
- Not of suitable quality for use in most applications
- High Crystalline Graphite (vein, lump or crystalline vein)
- Only extracted from Sri Lanka
- Carbon content of 90-99%
- Scarcity and high cost restricts viability for most applications
4. Lump graphite (or vein graphite) occurs in fissure veins or fractures and appears as massive platy intergrowths of fibrous or acicular crystalline aggregates, and is probably hydrothermal in origin.
5.Highly ordered pyrolytic graphite refers to graphite with an angular spread between the graphite sheets of less than 1°.
*Synthetic graphite is a manufactured product made by high-temperature treatment of amorphous carbon materials. In the United States, the primary feedstock used for making synthetic graphite is calcined petroleum coke and coal tar pitch. This makes it very expensive to produce — up to 10 times the cost of natural graphite – and less appealing for use in most applications. The name “graphite fiber” is sometimes used to refer to carbon fibers or carbon fiber-reinforced polymer.