The word garnet comes from the 14th century Middle English word gernet, meaning 'dark red'. It is derived from the Latin granatus, from granum ('grain, seed'). It refers to pomegranate fruits that contain abundant and vivid red seed covers (arils), which are similar in shape, size, and color to some garnet crystals.
Garnet sand is a good abrasive, and is a common replacement for silica sand in sand blasting. Alluvial garnet grains which are rounder are more suitable for such blasting treatments. Mixed with very high pressure water, garnet is used to cut steel and other materials in water jets. For water jet cutting, garnet extracted from hard rock is suitable since it is more angular in form, therefore more efficient in cutting.
Garnet paper is favored by cabinetmakers for finishing bare wood.
Garnet sand is also used for water filtration media.
As an abrasive, garnet can be broadly divided in two categories; blasting grade and water jet grade. The garnet, as it is mined and collected, is crushed to finer grains; all pieces which are larger than 60 mesh (250 micrometers) are normally used for sand blasting. The pieces between 60 mesh (250 micrometers) and 200 mesh (74 micrometers) are normally used for water jet cutting. The remaining garnet pieces that are finer than 200 mesh (74 micrometers) are used for glass polishing and lapping. Regardless of the application, the larger grain sizes are used for faster work and the smaller ones are used for finer finishes.
There are different kinds of abrasive garnets which can be divided based on their origin. The largest source of abrasive garnet today is garnet-rich beach sand which is quite abundant on Indian and Australian coasts and the main producers today are Australia and India.
This material is particularly popular due to its consistent supplies, huge quantities and clean nature. The common problems with this material are the presence of ilmenite and chloride compounds. Since the material has been naturally crushed and ground on the beaches for past centuries, the material is normally available in fine sizes only. Most of the garnet available at the Tuticorin beach in south India is 80 mesh, and ranges from 56 mesh to 100 mesh size.
River garnet is particularly abundant in Australia. The river sand garnet occurs as a placer deposit.
Rock garnet is perhaps the garnet type used for the longest period of time. This type of garnet is produced in America, China and western India. These crystals are crushed in mills and then purified by wind blowing, magnetic separation, sieving and, if required, washing. Being freshly crushed, this garnet has the sharpest edges and therefore performs far better than other kinds of garnet. Both the river and the beach garnet suffer from the tumbling effect of hundreds of thousands of years which rounds off the edges.
Garnet has been mined in western Rajasthan in northwestern India for the past 200 years, but mainly for the gemstone grade stones. Abrasive garnet was mainly mined as a secondary product while mining for gem garnets and was used as lapping and polishing media for the glass industries. The host rock of the garnet here is garnetiferous mica schist and the total percentage of garnet is not more than 7% to 10%, which makes the material extremely costly and non-economical to extract for non-gemstone applications.
Garnets are mined throughout the African continent, Australia, Brazil, Canada, Chile, China, the Czech Republic, India, Malaysia, Pakistan, Russia, Spain, Sri Lanka, Thailand, Ukraine, Uruguay, and the U.S.