What is Corundum

Corundum is a mineral and oxide of aluminum, which is a very hard, tough, and durable material. The mineral was first discovered in emery mines in Turkey during ancient times. It was given the name Corundum by Pliny the Elder in 79 AD, after the Sanskrit word "kurundam," which means ruby. Over the years, corundum has become one of the most valuable and widely used minerals in the world. In this article, we will cover all the knowledge points about corundum.

1. Chemical Properties
Corundum is an oxide of aluminum, with the chemical formula Al2O3. It is colorless, but it can also appear in various shades of red, blue, green, yellow, orange, and gray, depending on the presence of trace elements such as chromium, iron, titanium, and vanadium. The mineral has a hardness of 9 on the Mohs scale, making it one of the hardest minerals on earth. It is also very tough and durable, which makes it an ideal material for industrial applications.

2. Physical Properties
Corundum has a hexagonal crystal structure, and its crystals can be prismatic, tabular, or pyramidal in shape. It has a high refractive index of 1.76, which makes it a brilliant and lustrous mineral. The specific gravity of corundum is 3.95-4.10, which means it is a heavy mineral. Corundum has a conchoidal or uneven fracture, which allows it to cleave into smooth surfaces when hit or cut.

3. Occurrence
Corundum occurs in metamorphic and igneous rocks, such as schist, gneiss, granite, and basalt. Large deposits of corundum are found in countries such as Australia, India, Madagascar, Mozambique, Myanmar, Sri Lanka, and the United States. The mineral is mined from open-pit mines, alluvial deposits, and gemstone gravels. Corundum is also found as an accessory mineral in many other mineral deposits, such as bauxite, nepheline syenite, and pegmatites.

4. Uses
Corundum is used in a wide range of industrial applications, such as abrasives, refractories, ceramics, cutting tools, electrical insulation, and wear-resistant parts. The mineral is also used as a gemstone and is known for its durability, beauty, and variety of colors. Some of the famous corundum gemstones are Ruby, Sapphire, and Padparadscha. These gemstones are highly prized and can fetch high prices in the market. Corundum is also used as a catalyst in chemical reactions, such as the synthesis of ammonia and petroleum refining.

5. Production
Corundum production is mainly from mining and processing of the mineral. The mining process involves the extraction of ore from the earth's crust and then processing it into various products. The processing of corundum includes crushing, grinding, and sorting. After processing, corundum is used for industrial and gemstone purposes. The global production of corundum is estimated to be around 20 million tons per year, with the majority of production occurring in Australia, India, and China.

6. Health Hazards
Corundum is generally considered safe and non-toxic. However, exposure to fine dust particles of corundum can cause inhalation problems, such as respiratory irritation, coughing, and breathing difficulties. Long-term exposure to corundum dust can cause lung disease, including fibrosis and lung cancer. Workers in corundum mining, processing, and production industries are required to wear protective gear to minimize exposure to dust particles.

In conclusion, corundum is a highly valued mineral with a wide range of uses in the industry and as a gemstone. Its excellent properties, such as hardness, toughness, and durability, make it an ideal material for many applications. The mineral can be found in various parts of the world, and its production and processing have contributed significantly to the global economy. However, as with any mineral, caution must be taken when handling corundum to minimize exposure to health hazards.