Physical Properties and Crystal Structure of Garnet
- Garnet species are found in every color, with reddish shades being the most common.
- Blue garnets are the rarest and were first reported in the 1990s.
- Garnet species can range from transparent gemstone-quality specimens to opaque varieties used for industrial purposes.
- The luster of garnet can be vitreous (glass-like) or resinous (amber-like).
- Garnet can have any diaphaneity, but translucent is common.
- Garnets have a general formula of (SiO) with divalent cations occupying the site and trivalent cations occupying the site.
- Garnets are most often found in the dodecahedral crystal habit, but can also be found in the trapezohedron and hexoctahedral habits.
- They crystallize in the cubic system, with three axes of equal length perpendicular to each other.
- Garnets do not have any cleavage planes and fracture into sharp, irregular pieces.
- The crystal structure of garnet consists of oxygen, silicon, aluminium, and magnesium ions.
- The hardness of garnet varies depending on its chemical composition.
- Garnet has a range of hardness on the Mohs scale, from about 6.0 to 7.5.
- Harder species like almandine are often used for abrasive purposes.
- The atomic bonds in garnet species can be stronger or weaker, affecting their hardness.
- Garnet is not easily scratched and is relatively durable.
Identification of Garnet
- A strong neodymium magnet can be used to separate garnet from other transparent gemstones.
- Magnetic susceptibility measurements, along with refractive index, can help identify garnet species and determine their composition.
- This method is commonly used in gem identification in the jewelry trade.
- Garnets have unique magnetic properties that distinguish them from other gemstones.
- The response to a magnet can indicate the presence of garnet in a gemstone.
Garnet Group End Member Species
- Pyralspite garnets include almandine, pyrope, and spessartine.
- Almandine is an iron-aluminium garnet and is the most common gem garnet.
- Pyrope is a red garnet with magnesium silicate and can vary in color from deep red to black.
- Spessartine is a manganese-aluminium garnet and is found in orange-yellow varieties.
- Ugrandite garnets include andradite, grossular, and uvarovite, which have calcium in their composition.
Industrial Uses and Origin of Garnet
- Garnet sand is a common replacement for silica sand in sandblasting.
- Alluvial garnet grains are more suitable for blasting treatments.
- Garnet is used with high-pressure water to cut steel and other materials in water jets.
- Garnet paper is favored by cabinetmakers for finishing bare wood.
- Garnet sand is used for water filtration media.
- The largest source of abrasive garnet is garnet-rich beach sand found on Indian and Australian coasts.
- River garnet is particularly abundant in Australia and occurs as a placer deposit.
- Rock garnet is produced in America, China, and western India.
- Gore Mountain Garnet from New York, USA, is a significant source of rock garnet.
- Different kinds of abrasive garnets can be divided based on their origin.
Cultural Significance and Market of Garnet
- Garnet is the birthstone of January.
- It is also the birthstone of Aquarius and Capricorn in tropical astrology.
- In Persia, garnet was considered a talisman from nature's forces.
- Garnet was believed to signal approaching danger by turning pale.
- Garnet holds cultural significance in various traditions and beliefs.
- Garnet is New York State's official gemstone.
- Connecticut has almandine garnet as its state gemstone.
- Idaho has star garnet as its state gemstone.
- Vermont has grossular garnet as its state gemstone.
- New York State ranks first in industrial garnet production in the United States.
- The value of garnets depends on factors such as color, clarity, size, and origin.
- Garnets can range in price from affordable to high-end, depending on their quality and rarity.
- The market for garnets is influenced by consumer demand, fashion trends, and supply availability.
- Garnets are traded globally, with major markets in countries like the United States, India, and China.
- Garnets have cultural and symbolic value in different societies and can be considered a precious gemstone.
Garnet Data Sources