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Garnet Powder Description

  • Garnet Sand / Garnet Powder Synonyms:

iron aluminum silicate, garnet sand, garnet grain, garnet powder, garnet grit, almandite garnet, garnet grain, iron aluminum silicate, Fe3Al2(SiO4)3, iron aluminum silicate, CAS# 1302-62-1, calcium silicate, aluminum silicates, sands, inorganic abrasives, coast guard grade 36CG,

  • Garnet Sand / Garnet Powder Nominal Formula:

Fe3Al2(SiO4)3

  • Garnet Sand / Garnet Powder Description:

A group of iron aluminum silicate homogeneous minerals having similar properties. non-hygroscopic, sharp angular shape, inert, slightly magnetic, not soluble in water, translucent, friable to tough, and contains no free chemicals. All oxides and dioxides are combined chemically as follows: Fe2O3Al2(SiO4)3. The iron and aluminum are partially replaceable by calcium, magnesium and manganese.There are three types- aluminum garnet, iron garnet & chromium garnet.

  • Garnet Sand / Garnet Powder Typical Chemical Properties Available:

Typical Chemistry: SiO2= 41.34%, FeO= 9.72%, Fe2O3= 12.55%, Al2O3= 20.36%, CaO= 2.97%, MgO= 12.35% and MnO= 0.85%

  • Garnet Sand / Garnet Powder Typical Physical Properties Available:

1) Sintered pieces, targets, granules and various powder sizings

2) Grade 36CG (For Coast Guard marine deck abrasive paint applications)

  • Garnet Sand / Garnet Powder Nominal Physical Constants:
Fracture subconchoidal, usually brittle
Color red to pink
Bulk Density (lbs./ft3) 150.
Melting Point (°C) 1250 to 1315
Fusion Point (high Fe) (°C) 1200
Strength friable to tough
Mineral Conductivity (volts) 18,000
Mohs Hardness @20°C ~ 8 to 9
Category neosilicates 
Specific Gravity 3.9- 4.1
Mean Refractive Index 1.74- 1.89
Crystallography cubic
Facet Angles 37oC and 42oP

 

  • Garnet Sand / Garnet Powder Typical Applications:

1) Used in non-skid surfaces and heavily as a semi-precious stone

2) Garnet sand is a good abrasive, and 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.

3) Garnet paper is favoured by cabinetmakers for finishing bare wood.

4) Garnet sand is also used for water filtration media.

5) 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 micrometres) are normally used for sand blasting. The pieces between 60 mesh (250 micrometres) and 200 mesh (74 micrometres) are normally used for water jet cutting. The remaining garnet pieces that are finer than 200 mesh (74 micrometres) 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.

  • Garnet Sand / Garnet Powder Typical Packaging:

50 lbs. bags, poly-lined fiber drums and bulk bags

  • Garnet Sand / Garnet Powder Health Status:
“Acute Effects
 
(Effects of overexposure)
 
Inhalation:
Dust may cause irritation of nasal and respiratory tract.
Eye:
Dust may cause irritation.
Skin:
May cause abrasions.
Ingestion:
No known effects, however ingestion not recommended.
Medical Conditions Aggravated by Long-Term Exposure:  
Chronic respiratory disease may be aggravated by exposure to nuisance dust.
Emergency and First Aid Procedures:  
Inhalation:
Remove to fresh air, if breathing is difficult, administer oxygen, obtain medical assistance, if needed.
Eye Contact:
Flush with large amounts of water, obtain medical assistance, if needed.
Skin Contact:
Thoroughly wash exposed area with soap and water.
Ingestion:
Source: Barton Mines
Obtain first aid or medical assistance, if needed. “
  • Garnet Sand / Garnet Powder CAS Number:

CAS# 1302-62-1 (almandite garnet)

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Sharpjet Garnet Abrasive Media

Our Sharpjet garnet abrasive is manufactured and marketed according to ISO 9001 requirements. Sharpjet is produced in mines certified for listing on the QPL-22262 – MIL-A-22262B Abrasive Blasting Media (Cage: SGJ21). Sharpjet is an excellent source of washed, alluvial almandite garnet. Our customers are very pleased with the performance of Sharpjet for waterjet abrasive cutting applications and sandblasting abrasive applications.

Benefits of Sharpjet garnet abrasive

  • Sharpjet garnet is mined in its natural, angular form, making it one of the most sought-after abrasives in the business.
  • Environmentally and health-safe (contains no heavy metals)
  • Reduce air emissions greatly with garnet abrasive
  • Low dusting – due to its highly durable crystalline structure.
  • Mohs hardness of 7.5, Specific Gravity of 4.0 -
  • Virtually silica free (less than <0.5%) -
  • Low Chlorides
  • White metal finish without embedment
  • Mil Spec and CARB Approved, Meets AB1
  • With proper metering, 70% less abrasive is used than slag & cuts 30-40% faster than slag -
  • Unique grain-hardness/toughness reduces particle breakdown
  • Bulk density of 150 lbs/ft3 vs. 110 lbs. for sand & slag abrasives
  • Recycles 2-3 times
  • Lower abrasive disposal cost/lower containment cost
  • Supplied by Universal Minerals under Stringent QC Program

Garnet abrasive waterjet cutting applications

  • tile cutting
  • countertops
  • stone cutting
  • food processing equipment
  • glass cutting
  • Kevlar cutting
  • aluminum cutting
  • stainless steel cutting

Garnet abrasive sandblasting applications

  • turbine repair
  • heavy equipment repair
  • industrial painting contracting
  • shipbuilding and ship repair
  • blast rooms
  • denim blasting
  • powder coating
  • petrochemical

Sharpjet is available in the following grit sizes:

  • 16, 20/40, 30/40, 30/60, 36, 50, 60, 80 and 120

Sharpjet is available in the following bag sizes:

  • 55 lbs. bags, super sacks and pneumatic trailer
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Garnet Abrasives Over Other Abrasives

Advantages Over Other Abrasives
Cost-effective Blast Cleaning

GMA GarnetTM  abrasives are a more cost-effective solution over other abrasives. Contact Us to find out how we can help you achieve quality results at lower costs.

Low Dusting

Blast cleaning using GMA GarnetTM abrasives provide significantly lower dust emissions due to its inherent material toughness and rapid settling as a result of high specific gravity. This ensures minimum disruption and danger to adjoining operations and improved operator visibility and safety.

High Productivity

Very fast cutting is achieved with speed, large number and shape of grains impacting on the surface. The acceleration and speed of a grain in an air stream is a function of the inertia and hence the size of the grain. Smaller grains accelerate much more readily and impart higher impact energy to surfaces resulting in a superior cleaning rate – usually twice the m2/hr of conventional abrasives.

Low Consumption

The unique grain size ensures that there are many more active grains impacting the surface and this greatly reduces abrasive consumption.

Superior Surface Quality

GMA GarnetTM grains clean deep into the cavities and pitted areas down to the bare metal, thoroughly removing all rust, soluble salts and other contaminations. The blasted surface is free of embedment and rogue peaks and troughs. SA3 White Metal is effortlessly achieved. A surface profile of 50 – 75 microns is also easily achieved along with a much greater number of peaks per unit area.

Improved Health and Safety and Environment

GMA GarnetTM abrasives are non-toxic with no silicosis hazard or risk of contamination from leachable heavy metals or radioactive substances. Lower consumption and recyclability enables greatly reduced disposal volumes.

Recyclability

GMA GarnetTM abrasives are suitable for multiple usages and can be recycled 5 times or more without losing its superior cutting ability. Special GMA Garnet recycling systems are available upon request. These add up to natural, clean and cost effective blasting.

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Garnet Abrasive Mineral Manufacturer

We are reckoned as one of the preeminent Garnet Abrasives Manufacturers and Suppliers in India. The Garnet Abrasives, offered by us, have the specific gravity of is 3.95g / cm3.Of the six major varieties of garnet, we are into the production of almandine garnet stone, which is the best abrasive garnet stone. The Industrial Garnet Abrasives are widely demanded in the market for making organic bonded abrasive tools, abrasive blast media, denim blasting media, water filtration media, water jet-cutting abrasive, for glass polishing and high temperature gravel pack for deep oil wells. These Garnet Abrasives are also used in the applications of polishing, water filtration, cleaning, water-jet cutting and blasting etc. The raw material are pre-concentrated using the high magnetic separator to make free from contamination and get the 97 to 99% pure garnet. Garnet is screened accurately according to the customers’ need to produce consistent good quality garnet with hi-tech machineries. Therefore, the physical and chemical properties have also made the Garnet Abrasives ideal for non-abrasive application. Additionally, customers are eased with the availability of the Recyclable Garnet Abrasives in varied grades.

General Chemical & Physical Specification :

SiO2 : 36. 0-40. 0%Al2o3 : 20.0-24. 0%Feo2 : 2.0-24. 0%Fe2o3 : 4.0-6.0%MnO : 0-0.5%TiOsub>2 : 0-0. 5%MgO : 8-13%CaO : 1.2%Graivty : 3. 75-4. 30g / cm3Bulk Density : 2. 15g / cm3Hardness Moh’s : 7-8Melt Point : 1320 degree

Available Grit : 10 / 20 mesh, 20 / 40 mesh, 20 / 60 mesh, 30 / 60 mesh, f24-f150, f230-f1200. Other sizes can be also available upon request.

 

Products Details :

We are reckoned as one of the preeminent Garnet Abrasives Manufacturers and Suppliers in India. The Garnet Abrasives, offered by us, have the specific gravity of is 3.95g / cm3.Of the six major varieties of garnet, we are into the production of almandine garnet stone, which is the best abrasive garnet stone. The Industrial Garnet Abrasives are widely demanded in the market for making organic bonded abrasive tools, abrasive blast media, denim blasting media, water filtration media, water jet-cutting abrasive, for glass polishing and high temperature gravel pack for deep oil wells. These Garnet Abrasives are also used in the applications of polishing, water filtration, cleaning, water-jet cutting and blasting etc. The raw material are pre-concentrated using the high magnetic separator to make free from contamination and get the 97 to 99% pure garnet. Garnet is screened accurately according to the customers’ need to produce consistent good quality garnet with hi-tech machineries. Therefore, the physical and chemical properties have also made the Garnet Abrasives ideal for non-abrasive application. Additionally, customers are eased with the availability of the Recyclable Garnet Abrasives in varied grades.

General Chemical & Physical Specification :

SiO2 : 36. 0-40. 0%Al2o3 : 20.0-24. 0%Feo2 : 2.0-24. 0%Fe2o3 : 4.0-6.0%MnO : 0-0.5%TiOsub>2 : 0-0. 5%MgO : 8-13%CaO : 1.2%Graivty : 3. 75-4. 30g / cm3Bulk Density : 2. 15g / cm3Hardness Moh’s : 7-8Melt Point : 1320 degree

Available Grit : 10 / 20 mesh, 20 / 40 mesh, 20 / 60 mesh, 30 / 60 mesh, f24-f150, f230-f1200. Other sizes can be also available upon request.

 

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Garnet Abrasive Blasting Grit

Description

Garnet is a mineral abrasive produced from naturally occurring almandite garnet. Garnet is a cost effective, environmentally and operator friendly, alternative to silica sands and minerals slags and will provide a class Sa3 White Metal finish.

Garnet particles are dense, hard and sharp and free of heavy metals or toxic components. The low friability of garnet permits recycling up to 8 times and the relatively high density ensures fast blasting speeds.

Applications

Cleaning, descaling and surface preparation of structural steel fabrications in the oil, gas, petrochemical and shipyard industries prior to coating application.

Stainless steel and duplex blasting without ferrous contamination prior to coating. Surface preparation of aluminium and fiberglass ship hulls prior to painting.

Maintenance blasting of chemical plants, pipelines, mining equipment, power stations, petrochemical plants, gas tanks, rail and road bridges, masonry etc.

Size Details
Grit No. 10/20 20/40 30/60
Size in inch 0.033 – 0.078 0.017 – 0.033 0.008 – 0.023
Size in µm 850 – 2000 400 – 850 200 – 600
Physical Properties
Hardness Specific Gravity Bulk Density Shape Colour Chlorides
> 7.5 – 8.0 Mohs > 4.0 – 4.1 g/cm³ ≈ 2300kg/m³ Angular Red / Pink < 25ppm
Typical Chemical Composition
SiO2 Fe2O3 Al2O3 MgO CaO MnO
35% 33% 23% 7% 1% 1%
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Garnet Abrasive Applications

The garnet (pronounced /ɡɑrnət/) group includes a group of minerals that have been used since the Bronze Age as gemstones and abrasives. The name “garnet” comes from 14th century Middle English word gernet meaning ‘dark red’, from the Latin granatus granatus coming from granum (grain, seed) + suffix “atus”, possibly a reference to “mela granatum” or even “pomum granatum” (“pomegranate”, scientific name: “Punica granatum”), a plant whose abundant vivid red arils contained in the fruit are similar in shape, size, and color to some garnet crystals.

Six common species of garnet are recognized by their chemical composition. They are pyrope, almandine, spessartine, grossular (varieties of which are hessonite or cinnamon-stone and tsavorite), uvarovite and andradite. The garnets make up two solid solution series: pyrope-almandine-spessarite and uvarovite-grossular-andradite.

Red garnets were the most commonly used gemstones in the Late Antique Roman world, and the Migration Period art of the “barbarian” peoples who took over the territory of the Western Empire. They were especially used inlaid in gold cells in the cloisonné technique, a style often just called garnet cloisonné, found from Anglo-Saxon England, as at Sutton Hoo, to the Black Sea.

Pure crystals of garnet are still used as gemstones. The gemstone varieties occur in shades of green, red, yellow and orange. In the USA it is known as the birthstone for January. It is the state mineral of Connecticut, New York’s gemstone, and star garnet (garnet with rutile asterisms) is the state gemstone of Idaho.

Industrial uses

Garnet sand is a good abrasive, and 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 material. The common problems with this material are the presence of ilmenite and chloride compounds. Since the material is being naturally crushed and ground on the beaches for past centuries, the material is normally available in fine sizes only. Most of the garnet at the Tuticorin beach is 80 mesh, and ranges from 56 mesh to 100 mesh size.[citation needed]

River garnet is particularly abundant in Australia. The river sand garnet occurs as a placer deposit.[citation needed]

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 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%,[citation needed] which makes the material extremely costly and non economical to extract for non-gemstone applications.

Garnet is also finding a niche in solid state circuitry. MIT recently published an article on the use of Garnet as an optical component in a new photonic chip.

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Garnet Blasting Media Sale

Specifications

1.our Garnet will offer you many benefits:

2.low consumption; superior surface quality

3.low dusting ; high productivity;

Garnet is an alternative to traditional abrasive such as silica sand and slag. The color of Donghai Garnet is light red. It turns to light grew or milky white when it becomes micro-powder.

our Garnet is non-toxic and contains less than 0.1% “free silica”. There is no silicosis hazard, leachable heavy metals or radioactive.

Chemical & Physical Specification

SiO2 36.0-40% Graivty 3.98
Al2O3 20.0–24.0% Bulk Density(#80) 2.15g/cm3
FeO            22.0-24.0% Hardness Mohs 8.2
Fe2O3 4.0-6.0% Melt point 1400 C
MnO 00.5% Free Silica 0.1% Max
TiO2 00.5%    
MgO 1.50%    
CaO 1.90%    

Typical applications:

Lapping

Making coated or bonded abrasive tools

Sand blasting media

Denim blasting

Water filtration media

Water jet-cutting abrasive

Glass polishing

High temperature gravel pack for deep oil wells.

Available Grit  &  Typical applications:

Grit No.

Mesh

Micron

Typical application

10/20

10–20

2000 ~ 850

Water filtration media

20/40

20–40

850 ~ 425

Sand blasting media

30/60

30–60

600 ~ 250

Sand blasting media

40/60

40–60

425–250

Water jet-cutting abrasive suggested materials: tile, Marble, granite, stone, stainless steel, steel plate.

60/90

60–90

250–160

Water jet-cutting abrasive (suggested materials: tile, marble, granite, stone, stainless steel, steel plate, glass, aluminum alloy. And other precious metal )

90/120

90–120

160–125

Precise water jet-cutting, hole drilling,  lapping .

120/180

120–180

12580

Precise water jet-cutting, hole drilling,  lapping

180/240

180–240

80–63

 hole drilling, lapping

24

20–25

850–710

Sand blasting media ,lapping .,making coated or bonded abrasive tools

30

25–30

710–600

Sand blasting media ,lapping .,making coated or bonded abrasive tools

36

 30–35  600–500

Sand blasting media ,lapping .,making coated or bonded abrasive tools

40

35–40

500–425

Sand blasting media ,lapping .making coated or bonded abrasive tools

46

40–45

425–355

Sand blasting media ,lapping .making coated or bonded abrasive tools

54

45–50

355–300

Sand blasting media ,lapping .making coated or bonded abrasive tools

60

50–60

300-250

Water jet-cutting abrasive, Sand blasting media ,lapping .making coated or bonded abrasive tools

70

60–70

250–212

Water jet-cutting abrasive, Sand blasting media ,lapping .making coated or bonded abrasive tools

80

70–80

212–180

Water jet-cutting abrasive ,Sand blasting media ,lapping .making coated or bonded abrasive tools

 

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Garnet Sand Blasting Specifications

The finish grinding pieces of the high sand marks few and shallow, thin and uniform grinding. With a shell-like fracture of the

    Natural corundum, also known as garnet sand, ancient times, China will have the use of emery grinding crystal glass, all kinds of jade examples. Product specifications are 20 kinds of divided into: coarse, medium, fine three categories, coarse mesh for the black and red, medium brown red head, broken down as a red light, all kinds of mesh size uniform. Uniform particle shape,

Cheng caltrop crystal, there are sharp edges, grinding high strength, hardness of 7-8 degrees. Coarse mesh for the sand-blasting exclusive use of mesh for the water jet private, dedicated lines for wear-resistant materials. As markets open up the development of functional fillers such as automotive brake parts, specialty tires, specialty construction products in areas such as construction of highway roads, runways, car parks, industrial floors and other sports venues. Filter Media: Pomegranate is also a new application areas of sand, using granular garnet sand as the bottom of the bed media filter, purify water or wastewater applications, is home to a new type of water filtration materials, especially for non-ferrous mineral processing, oil drilling mud increasing agent .

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Garnet Blasting Introduction

The garnet group includes a group of minerals that have been used since the Bronze Age as gemstones and abrasives. The name “garnet” comes from 14th century Middle English word gernet meaning ‘dark red’, from the Latin granatus granatus coming from granum (grain, seed) + suffix “atus”, possibly a reference to “mela granatum” or even “pomum granatum” (“pomegranate”, scientific name: “Punica granatum”), a plant whose abundant vivid red arils contained in the fruit are similar in shape, size, and color to some garnet crystals.

Six common species of garnet are recognized by their chemical composition. They are pyrope, almandine, spessartine, grossular (varieties of which are hessonite or cinnamon-stone and tsavorite), uvarovite and andradite. The garnets make up two solid solution series: pyrope-almandine-spessarite and uvarovite-grossular-andradite.

Physical properties

Properties

Garnet species are found in many colors including red, orange, yellow, green, blue, purple, brown, black, pink and colorless. The rarest of these is the blue garnet, discovered in the late 1990s in Bekily, Madagascar. It is also found in parts of the United States, Russia and Turkey. It changes color from blue-green in the daylight to purple in incandescent light, as a result of the relatively high amounts of vanadium (about 1 wt.% V2O3). Other varieties of color-changing garnets exist. In daylight, their color ranges from shades of green, beige, brown, gray, and blue, but in incandescent light, they appear a reddish or purplish/pink color. Because of their color changing quality, this kind of garnet is often mistaken for Alexandrite.

Garnet species’ light transmission properties can range from the gemstone-quality transparent specimens to the opaque varieties used for industrial purposes as abrasives. The mineral’s luster is categorized as vitreous (glass-like) or resinous (amber-like).

Crystal structure

Garnets are nesosilicates having the general formula X3Y2(Si O4)3. The X site is usually occupied by divalent cations (Ca2+, Mg2+, Fe2+) and the Y site by trivalent cations (Al3+, Fe3+, Cr3+) in an octahedral/tetrahedral framework with [SiO4]4− occupying the tetrahedra. Garnets are most often found in the dodecahedral crystal habit, but are also commonly found in the trapezohedron habit. (Note: the word “trapezohedron” as used here and in most mineral texts refers to the shape called a Deltoidal icositetrahedron in solid geometry.) They crystallize in the cubic system, having three axes that are all of equal length and perpendicular to each other. Garnets do not show cleavage, so when they fracture under stress, sharp irregular pieces are formed.

Hardness

Because the chemical composition of garnet varies, the atomic bonds in some species are stronger than in others. As a result, this mineral group shows a range of hardness on the Mohs Scale of about 6.5 to 7.5. The harder species, like almandine, are often used for abrasive purposes.

Garnet group endmember species

Pyralspite garnets – aluminium in Y site

  • Almandine: Fe3Al2(SiO4)3
  • Pyrope: Mg3Al2(SiO4)3
  • Spessartine: Mn3Al2(SiO4)3

Almandine

Almandine, sometimes incorrectly called almandite, is the modern gem known as carbuncle (though originally almost any red gemstone was known by this name). The term “carbuncle” is derived from the Latin meaning “live coal” or burning charcoal. The name Almandine is a corruption of Alabanda, a region in Asia Minor where these stones were cut in ancient times. Chemically, almandine is an iron-aluminium garnet with the formula Fe3Al2(SiO4)3; the deep red transparent stones are often called precious garnet and are used as gemstones (being the most common of the gem garnets). Almandine occurs in metamorphic rocks like mica schists, associated with minerals such as staurolite, kyanite, andalusite, and others. Almandine has nicknames of Oriental garnet, almandine ruby, and carbuncle.

Pyrope

Pyrope (from the Greek pyrōpós meaning “fire-eyed”) is red in color and chemically a magnesium aluminium silicate with the formula Mg3Al2(SiO4)3, though the magnesium can be replaced in part by calcium and ferrous iron. The color of pyrope varies from deep red to almost black. Transparent pyropes are used as gemstones.

A variety of pyrope from Macon County, North Carolina is a violet-red shade and has been called rhodolite, from the Greek meaning “a rose.” In chemical composition it may be considered as essentially an isomorphous mixture of pyrope and almandine, in the proportion of two parts pyrope to one part almandine. Pyrope has tradenames some of which are misnomers; Cape ruby, Arizona ruby, California ruby, Rocky Mountain ruby, and Bohemian garnet from the Czech Republic. Another intriguing find is the blue color-changing garnets from Madagascar, a pyrope spessartine mix. The color of these blue garnets is not like sapphire blue in subdued daylight but more reminiscent of the grayish blues and greenish blues sometimes seen in spinel. However, in white LED light the color is equal to the best cornflower blue sapphire, or D block tanzanite; this is due to the blue garnet’s ability to absorb the yellow component of the emitted light.

Pyrope is an indicator mineral for high-pressure rocks. The garnets from mantle derived rocks, peridotites and eclogites, commonly contain a pyrope variety.

Spessartine

Spessartine or spessartite is manganese aluminium garnet, Mn3Al2(SiO4)3. Its name is derived from Spessart in Bavaria. It occurs most often in granite pegmatite and allied rock types and in certain low grade metamorphic phyllites. Spessartine of an orange-yellow is found in Madagascar. Violet-red spessartines are found in rhyolites in Colorado and Maine.

Ugrandite group – calcium in X site

  • Andradite: Ca3Fe2(SiO4)3
  • Grossular: Ca3Al2(SiO4)3
  • Uvarovite: Ca3Cr2(SiO4)3

Andradite

Andradite is a calcium-iron garnet, Ca3Fe2(SiO4)3, is of variable composition and may be red, yellow, brown, green or black. The recognized varieties are topazolite (yellow or green), demantoid (green) and melanite (black). Andradite is found both in deep-seated igneous rocks like syenite as well as serpentines, schists, and crystalline limestone. Demantoid has been called the “emerald of the Urals” from its occurrence there, and is one of the most prized of garnet varieties. Topazolite is a golden yellow variety and melanite is a black variety.

Grossular

Grossular is a calcium-aluminium garnet with the formula Ca3Al2(SiO4)3, though the calcium may in part be replaced by ferrous iron and the aluminium by ferric iron. The name grossular is derived from the botanical name for the gooseberry, grossularia, in reference to the green garnet of this composition that is found in Siberia. Other shades include cinnamon brown (cinnamon stone variety), red, and yellow. Because of its inferior hardness to zircon, which the yellow crystals resemble, they have also been called hessonite from the Greek meaning inferior. Grossular is found in contact metamorphosed limestones with vesuvianite, diopside, wollastonite and wernerite.

Grossular garnet from Kenya and Tanzania has been called tsavorite. Tsavorite was first described in the 1960s in the Tsavo area of Kenya, from which the gem takes its name.[citation needed]

Uvarovite

Uvarovite is a calcium chromium garnet with the formula Ca3Cr2(SiO4)3. This is a rather rare garnet, bright green in color, usually found as small crystals associated with chromite in peridotite, serpentinite, and kimberlites. It is found in crystalline marbles and schists in the Ural mountains of Russia and Outokumpu, Finland.

Less common species

  • Calcium in X site
    • Goldmanite: Ca3V2(SiO4)3
    • Kimzeyite: Ca3(Zr,Ti)2[(Si,Al,Fe3+)O4]3
    • Morimotoite: Ca3Ti4+Fe2+(SiO4)3
    • Schorlomite: Ca3(Ti4+,Fe3+)2[(Si,Ti)O4]3
  • Hydroxide bearing – calcium in X site
    • Hydrogrossular: Ca3Al2(SiO4)3-x(OH)4x
      • Hibschite: Ca3Al2(SiO4)3-x(OH)4x (where x is between 0.2 and 1.5)
      • Katoite: Ca3Al2(SiO4)3-x(OH)4x (where x is greater than 1.5)
  • Magnesium or manganese in X site
    • Knorringite: Mg3Cr2(SiO4)3
    • Majorite: Mg3(Fe2+Si)(SiO4)3
    • Calderite: Mn3Fe3+2(SiO4)3

Knorringite

Knorringite is a magnesium chromium garnet species with the formula Mg3Cr2(SiO4)3. Pure endmember knorringite never occurs in nature. Pyrope rich in the knorringite component is only formed under high pressure and is often found in kimberlites. It is used as an indicator mineral in the search for diamonds.

Garnet structural group

  • Formula: X3Z2(TO4)3 (X = Ca, Fe, etc., Z = Al, Cr, etc., T = Si, As, V, Fe, Al)
    • All are cubic or strongly pseudocubic.
IMA/CNMNC

Nickel-Strunz

Mineral class

Mineral name Formula Crystal system Point group Space group
04 Oxide Bitikleite-(SnAl) Ca3SnSb(AlO4)3 isometric m3m Ia3d
04 Oxide Bitikleite-(SnFe) Ca3(SnSb5+)(Fe3+O)3 isometric m3m Ia3d
04 Oxide Bitikleite-(ZrFe) Ca3SbZr(Fe3+O4)3 isometric m3m Ia3d
04 Tellurate Yafsoanite Ca3Zn3(Te6+O6)2 isometric m3m

or 432

Ia3d

or I4132

08 Arsenate Berzeliite NaCa2Mg2(AsO4)3 isometric m3m Ia3d
08 Vanadate Palenzonaite NaCa2Mn2+2(VO4)3 isometric m3m Ia3d
08 Vanadate Schäferite NaCa2Mg2(VO4)3 isometric m3m Ia3d
  • IMA/CNMNC – Nickel-Strunz – Mineral subclass: 09.A Nesosilicate
    • Nickel-Strunz classification: 09.AD.25
Mineral name Formula Crystal system Point group Space group
Almandine Fe2+3Al2(SiO4)3 isometric m3m Ia3d
Andradite Ca3Fe3+2(SiO4)3 isometric m3m Ia3d
Calderite Mn+23Fe+32(SiO4)3 isometric m3m Ia3d
Goldmanite Ca3V3+2(SiO4)3 isometric m3m Ia3d
Grossular Ca3Al2(SiO4)3 isometric m3m Ia3d
Henritermierite Ca3Mn3+2(SiO4)2(OH)4 tetragonal 4/mmm I41/acd
Hibschite Ca3Al2(SiO4)(3-x)(OH)4x (x= 0.2–1.5) isometric m3m Ia3d
Katoite Ca3Al2(SiO4)(3-x)(OH)4x (x= 1.5-3) isometric m3m Ia3d
Kerimasite Ca3Zr2(Fe+3O4)2(SiO4) isometric m3m Ia3d
Kimzeyite Ca3Zr2(Al+3O4)2(SiO4) isometric m3m Ia3d
Knorringite Mg3Cr2(SiO4)3 isometric m3m Ia3d
Majorite Mg3(Fe2+Si)(SiO4)3 tetragonal 4/m

or 4/mmm

I41/a

or I41/acd

Momoiite Mn2+3V3+2(SiO4)3 isometric m3m Ia3d
Morimotoite Ca3(Fe2+Ti4+)(SiO4)3 isometric m3m Ia3d
Pyrope Mg3Al2(SiO4)3 isometric m3m Ia3d
Schorlomite Ca3Ti4+2(Fe3+O4)2(SiO4) isometric m3m Ia3d
Spessartine Mn2+3Al2(SiO4)3 isometric m3m Ia3d
Toturite Ca3Sn2(Fe3+O4)2(SiO4) isometric m3m Ia3d
Uvarovite Ca3Cr2(SiO4)3 isometric m3m Ia3d
  • References: Mindat.org; mineral name, chemical formula and space group (American Mineralogist Crystal Structure Database) of the IMA Database of Mineral Properties/ RRUFF Project, Univ. of Arizona, was preferred most of the time. Minor components in formulae have been left out to highlight the dominant chemical endmember that defines each species.

Synthetic garnets

The crystallographic structure of garnets has been expanded from the prototype to include chemicals with the general formula A3B2(C O4)3. Besides silicon, a large number of elements have been put on the C site, including Ge, Ga, Al, V and Fe.

Yttrium aluminium garnet (YAG), Y3Al2(AlO4)3, is used for synthetic gemstones. Due to its fairly high refractive index, YAG was used as a diamond simulant in the 1970s until the methods of producing the more advanced simulant cubic zirconia in commercial quantities were developed. When doped with neodymium (Nd3+), these YAl-garnets may be used as the lasing medium in lasers.

Interesting magnetic properties arise when the appropriate elements are used. In yttrium iron garnet (YIG), Y3Fe2(FeO4)3, the five iron(III) ions occupy two octahedral and three tetrahedral sites, with the yttrium(III) ions coordinated by eight oxygen ions in an irregular cube. The iron ions in the two coordination sites exhibit different spins, resulting in magnetic behaviour. YIG is a ferrimagnetic material having a Curie temperature of 550 K.

Another example is gadolinium gallium garnet, Gd3Ga2(GaO4)3 which is synthesized for use as a substrate for liquid phase epitaxy of magnetic garnet films for bubble memory and magneto-optical applications.

Geological importance of garnet

The Garnet group is a key mineral in interpreting the genesis of many igneous and metamorphic rocks via geothermobarometry. Diffusion of elements is relatively slow in garnet compared to rates in many other minerals, and garnets are also relatively resistant to alteration. Hence, individual garnets commonly preserve compositional zonations that are used to interpret the temperature-time histories of the rocks in which they grew. Garnet grains that lack compositional zonation commonly are interpreted as having been homogenized by diffusion, and the inferred homogenization also has implications for the temperature-time history of the host rock.

Garnets are also useful in defining metamorphic facies of rocks. For instance, eclogite can be defined as a rock of basalt composition, but mainly consisting of garnet and omphacite. Pyrope-rich garnet is restricted to relatively high-pressure metamorphic rocks, such as those in the lower crust and in the Earth’s mantle. Peridotite may contain plagioclase, or aluminium-rich spinel, or pyrope-rich garnet, and the presence of each of the three minerals defines a pressure-temperature range in which the mineral could equilibrate with olivine plus pyroxene: the three are listed in order of increasing pressure for stability of the peridotite mineral assemblage[vague]. Hence, garnet peridotite must have been formed at great depth in the earth. Xenoliths of garnet peridotite have been carried up from depths of 100 km and greater by kimberlite, and garnets from such disaggegated xenoliths are used as a kimberlite indicator minerals in diamond prospecting. At depths of about 300 to 400 km and greater, a pyroxene component is dissolved in garnet, by the substitution of (Mg,Fe) plus Si for 2Al in the octahedral (Y) site in the garnet structure, creating unusually silica-rich garnets that have solid solution towards majorite. Such silica-rich garnets have been identified as inclusions within diamonds.

Uses of garnets

Red garnets were the most commonly used gemstones in the Late Antique Roman world, and the Migration Period art of the “barbarian” peoples who took over the territory of the Western Empire. They were especially used inlaid in gold cells in the cloisonné technique, a style often just called garnet cloisonné, found from Anglo-Saxon England, as at Sutton Hoo, to the Black Sea.

Pure crystals of garnet are still used as gemstones. The gemstone varieties occur in shades of green, red, yellow and orange. In the USA it is known as the birthstone for January. It is the state mineral of Connecticut, New York’s gemstone, and star garnet (garnet with rutile asterisms) is the state gemstone of Idaho.

Industrial uses

Garnet sand is a good abrasive, and 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 material. The common problems with this material are the presence of ilmenite and chloride compounds. Since the material is being naturally crushed and ground on the beaches for past centuries, the material is normally available in fine sizes only. Most of the garnet at the Tuticorin beach is 80 mesh, and ranges from 56 mesh to 100 mesh size.[citation needed]

River garnet is particularly abundant in Australia. The river sand garnet occurs as a placer deposit.[citation needed]

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 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%,[citation needed] which makes the material extremely costly and non economical to extract for non-gemstone applications.

Garnet is also finding a niche in solid state circuitry. MIT recently published an article on the use of Garnet as an optical component in a new photonic chip.

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Garnet Abrasive Blasting Grit

Description

Garnet is a mineral abrasive produced from naturally occurring almandite garnet. Garnet is a cost effective, environmentally and operator friendly, alternative to silica sands and minerals slags and will provide a class Sa3 White Metal finish.

Garnet particles are dense, hard and sharp and free of heavy metals or toxic components. The low friability of garnet permits recycling up to 8 times and the relatively high density ensures fast blasting speeds.

Applications

Cleaning, descaling and surface preparation of structural steel fabrications in the oil, gas, petrochemical and shipyard industries prior to coating application.

Stainless steel and duplex blasting without ferrous contamination prior to coating. Surface preparation of aluminium and fiberglass ship hulls prior to painting.

Maintenance blasting of chemical plants, pipelines, mining equipment, power stations, petrochemical plants, gas tanks, rail and road bridges, masonry etc.

Size Details
Grit No. 10/20 20/40 30/60
Size in inch 0.033 – 0.078 0.017 – 0.033 0.008 – 0.023
Size in µm 850 – 2000 400 – 850 200 – 600
Physical Properties
Hardness Specific Gravity Bulk Density Shape Colour Chlorides
> 7.5 – 8.0 Mohs > 4.0 – 4.1 g/cm³ ≈ 2300kg/m³ Angular Red / Pink < 25ppm
Typical Chemical Composition
SiO2 Fe2O3 Al2O3 MgO CaO MnO
35% 33% 23% 7% 1% 1%
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