Diamond and Graphite

Diamonds and graphite are two minerals that are chemically identical, but physically they are very different. Both are composed of the same element, carbon. Diamond is a solid form of carbon with a crystal structure, whereas graphite is a crystal form of carbon with a hexagonal pattern. Polymorphs include diamond and graphite. Minerals that are chemically the same but physically different are called polymorphs.

Diamonds

• Diamonds are naturally occurring solid forms of carbon with atoms arranged in a crystal structure known as diamond cubic

• Each atom of carbon is surrounded by four other carbon atoms, and they are connected by covalent bonds, which are the strongest of all bonds

• It is the hardest known mineral

• It is the most popular and expensive gemstone, in many cultures, there is a custom to propose to the girl to marry with diamonds, which makes its demand

Structure of Diamonds

• Diamonds have a crystallographic structure 

• It has a cubic structure

• The crystal structure of diamond is an FCC or face-centred lattice 

• A lattice is an organised set of points that define the structure of crystal-forming particles

• There are three types of lattice structures that are face-centred or FCC, body-centred or BCC, and hexagonal closest packed HCP

• All of the carbon atoms in diamond are connected to four other carbon atoms by strong chemical bonds, forming a tetrahedron structure throughout the crystal

• Sp³ hybridisation is a type of carbon atom hybridisation

• Diamond makes a three-dimensional network with a strong covalent bond

Diamond

Occurrence

Diamonds do not present in that shining form that we see, they are like normal stones. 

Diamonds occur in two types of deposits: 

• Volcanic pipes are also called kimberlite pipes

• In Alluvial deposits, which are formed by the erosion of diamond pipes

Uses of diamond

• Diamonds are used in making tools that are used for cutting, drilling, grinding etc

• They are used in making jewellery

• Diamonds are also used in medical instruments, such as high precision instruments which surgeons used for the removal of eye cataracts

Graphite

• Graphite is a mineral composed of carbon, also known as plumbago or black lead

• It is a naturally occurring, crystalline form of carbon with a hexagonal structure system

• Graphite is reported in metamorphic and igneous rocks

• It is used in manufacturing of pencils, metallurgy

• When carbon is exposed to heat and pressure in the Earth’s crust, graphite is formed.

Structure of graphite

• Graphites are formed by the metamorphosis of sedimentary rocks containing carbon material

• The layered structure of graphite is made up of rings of six carbon atoms organised in horizontal sheets that are widely spaced

• As a result, the graphite crystallises in the hexagonal system, as opposed to diamond, which crystallises in the octahedral or tetrahedral systems

• They are of dark black to grey colour, opaque, and soft

Types of Graphite

There are varieties of Graphite present on the basis of occurrence and ore.

• Crystalline form: These are small crystalline flakes, present as separated, fate plate-like structures with hexagonal edges, but edges can be irregular.

• Amorphous graphite: It is a very fine flake structure.

• Lump graphite: Also called the vein Graphite, they are present in fractures and veins in fissures.

• Pyrolytic graphite: They are referred to as graphite with a smaller than 1° angular spread between the graphite sheets.

Occurrence of Graphite

• Graphite is found naturally in the earth’s crust, most found on the surface of the earth are made at the convergent plate boundaries

• Graphite is present in marbles, limestone, and schist

• The graphite is removed from them by mining and crushing of these minerals and then separating by flotation or specific gravity separation

Uses of Graphite

• Graphite powder is used as a lubricant in the form of dispersion material or powder

• Graphite is often used in lead pencils

• Because it is a good conductor of electricity, it is used to make carbon electrodes for electrolytic cells

• It is utilised in the fabrication of graphite crucibles due to its high melting point

• Many moderators and nuclear reactors include it

Conclusion

Diamonds and graphite are two types of carbon that are slightly different. Diamonds are a hard mineral, while graphite is a soft one. Diamonds are found in the mantle of the earth, where graphite can be found near the earth’s surface. They share the same compositions but are different in structures.

The use of graphite is highest in the production of electrodes and other items. Synthetic graphite can also be created by heating carbon-rich materials like petroleum coke and coal tar.

The diamonds are used largely in the jewellery industry, automotive industries, and in medicines, and beauty products. Synthetic Diamonds are made in labs, they are man-made diamonds, manufactured by artificial processes such as CVD (chemical vapour deposition).