Graphite is a naturally-occurring form of crystalline carbon. It is a native element mineral found in metamorphic and igneous rocks. It is a mineral of extremes. It is extremely soft, cleaves with very light pressure and has a very low specific gravity. In contrast, it is extremely resistant to heat and nearly inert in contact with almost any other material. These extreme properties give it a wide range of uses in metallurgy and manufacturing.
Graphite is a soft grayish-black greasy substance. The word graphite comes from a Greek word meaning to write. The lead in our writing pencils is graphite mixed with clay. It is also known as black lead or plumbago.
Graphite is also crystallized carbon. The carbon atoms of it form a crystal pattern that differs from that of the carbon atoms in diamond.
Occurrence:
Natural graphite is mined in Bihar, Andhra Pradesh, Jammu and Kashmir, Odisha, Rajasthan, Tamil Nadu and Uttar Pradesh. Other than in Indian, it is found in Sri Lanka and Russia. In the United States it is mined in New York and Pennsylvania.
Properties of graphite:
1. It is a soft, slippery, grayish-black substance. It has a metallic luster and is opaque to light.
2. Specific gravity is 2.3.
3. It is a good conductor of heat and electricity
4. Although it is a very stable allotrope of carbon but at a very high temperature it can be transformed into artificial diamond.
5. Chemically, it is slightly more reactive than diamond.
1. The major use of graphite is in making lead pencils of different hardness, by mixing it with different proportions of clay. The weakly held layers of carbon atoms in it easily slide over each other and are left behind on paper as black marks.
2. Due to its slippery nature, graphite is used as a dry lubricant in machine parts.
3. Being resistant to chemicals and having a high melting point and also because it is a good conductor of heat, it is used to make crucibles.
4. The presence of free electrons makes it a good conductor of electricity and it is used to make electrodes.
5. It has the ability to absorb fast-moving neutrons, thus, it is used in nuclear reactors to control the speed of the nuclear fission reaction.
<h2>Crystalline flake graphite</h2>
Crystalline flake graphite or flake graphite for short occurs as isolated, flat, plate-like particles with hexagonal edges if unbroken and when broken the edges can be irregular or angular.
<h2>Amorphous graphite</h2>
Amorphous graphite is a very fine flake is sometimes called amorphous in the trade.
<h2>Lump graphite</h2>
It is also called vein graphite occurs in fissure veins or fractures and appears as massive platy inter growths of fibrous or acicular crystalline aggregates, and is probably hydrothermal in origin.
<h2>Pyrolytic graphite</h2>
Highly ordered pyrolytic graphite or highly oriented pyrolytic graphite (HOPG) refers to graphite with an angular spread between the graphite sheets of less than 1 degree.
