GARNET
Garnets are a group of silicate minerals that have been used as gemstones and abrasives since the Bronze Age. They have similar physical properties and crystal forms, but differ in chemical composition. Some types of garnets include:
- Pyrope
- Almandine
- Andradite
- Grossular
- Uvarovite
- Spessartine
- Rhodolite
- Topazolite
- Hessonite
- Dermantoid
- Malaya
Garnets are a set of closely related minerals that form a group, resulting in gemstones in almost every color. Red garnets have a long history, but modern gem buyers can pick from a rich palette of garnet colors: greens, oranges, pinkish oranges, deeply saturated purplish reds, and even some blues.
The garnet gemstone was very popular with the Romans in the third and fourth centuries. This gemstone was used as a talisman for protection.
USES
Today, the vast majority are used as an abrasive blasting material, for water filtration, in a process called water jet cutting, and to make abrasive powders.
They are used in a variety of industrial applications, including:
- Abrasive blastings.
- Water filtration: used as a media for water filtration.
- Water jet cutting: used in water jet cutting, a process that uses a high-pressure jet of water with garnet to cut materials like stone, metal, or ceramic.
- Abrasive powders: used in abrasive powders.
- Nonslip coatings: used in nonslip coatings.
- Sandpaper: used in sandpaper.
- Jewelry
MOHS HARDNESS
Rated between 6.5 and 7.5 on the Mohs scale of mineral hardness.
The hardness depends on its type and variety. For example, almandine, pyrope, spessartine, tsavorite, and demantoid are all harder varieties.
LUSTER
The luster ranges from vitreous to resinous to subadamantine. Colors can be red, brown, yellow, orange, white, green, or black or shades in between. The refractive index can vary somewhat.
CHEMICAL COMPOUND
It is a rather complex mineral that has a general chemical formula of R3R2(SiO4)3, where R3 is a bivalent (gives up two electrons) metal and R2 is a trivalent (gives up three electrons) metal when forming a chemical bond.
WHERE TO FIND
They can be found all over the world in a variety of locations, including:
Garnet Hill, Nevada: A well-known rock hounding area for garnets, located in the Ely District. They can be found in the rhyolite rock, either by breaking rocks or searching the ground.
Idaho Panhandle National Forests: The Garnet Area is a safe place for the public to collect Star Garnets.
San Diego County, California: Pegmatites in this area are known for producing high-quality spessartite specemins.
Brazil: Home to many varieties.
Namibia: Known for its spessartine specimens with strong orange hues.
Kenya: Home to the Scorpion mine, which is famous for its tsavorite specemins.
Tanzania: The first place where tsavorite, a green variety, was discovered.
Iran: A recent discovery of demantoid, a green garnet variety, has made Iran a new supplier of the gem.
They are more commonly found in metamorphic rocks, but they can also be found in some igneous rocks and pegmatites. The type of metamorphism that occurs determines the type of garnet that forms. For example, aluminum garnets form in areas of regional metamorphism, while calcium garnets form at locations of contact metamorphism.
DIAGNOSTIC PROPERTIES
- Color
- Hardness
- Specific gravity
The specific gravity of a garnet ranges from 3.5 to 4.3, and varies depending on its composition. - Crystal habit
They typically crystallize in dodecahedral, trapezohedral, or hexoctahedral shapes. - Luster
- Cleavage
Garnets lack cleavage, so when they break, they form sharp, irregular pieces. - Chemical composition
The chemical formula for garnet is A3B2(SiO4)3, where A can be Fe2+, Mg, Mn, or Ca, and B is Al, Cr, or Fe3+.