Specifications of garnet stone
Garnet is a stone with a cubic crystal system and a hardness of 6.5 to 7.5 on the Mohs scale. The presence of different elements in this mineral has caused it to have various combinations with different colors. The rhombic forms of dodecahedron and trapezoidron are also characteristic of this group of minerals
Most garnets are formed in contact with intrusive masses with calcareous host rocks or in schists, shales, cooling internal igneous rocks, and sedimentary units such as granites, pegmatites, and granodiorites. Garnet is colloquially referred to as red crystals of the almandine and pyrope type. Garnet is usually formed in metamorphic rocks and is resistant to physical and chemical weathering
Types of garnet
In general, discoloration of gemstones is due to impurities in the host crystals. The same is true of garnet. However, in some cases, it is difficult to identify which mineral is causing the dye. Also, some gemstones, including some types of garnet, derive their color from their original chemical formula and not from added impurities
The color of red and brown garnets is due to the small elements of iron in their crystal structure during formation. Orange and pink garnets are made of manganese, yellow of calcium and green of aluminum, chromium or vanadium. Depending on the composition of these minor impurities, garnets have unique colors and shades. For example, a mixture of iron and chromium produces a purple / violet garnet
Like all gemstones, rare color garnets are the most expensive. Some of the rarest color garnets are: Spesartine, which is rich in red-orange, also called mandarin. Or a trio rich in green, tsavorite, dantoid and avarovit. The most valuable type, however, is garnet coloring, which is extracted from Madagascar and Tanzania and appears blue in daylight and red or purple in artificial light. There is no pure blue garnet
This mineral has two categories and several subgroups based on chemical compounds and according to their color and difference in refractive index, which we will explain
Pyralspite category includes
Pyrope garnet
Pyropos is derived from the Greek word pyrpos meaning “fiery” and is reddish-orange, reddish brown to dark red or purple in color. Its color is due to the presence of Mg manganese in its silicate composition. The pyruvate is crystal clear to translucent and may be confused with almandine and spinel garnet, ruby and artificial ruby, glass and tourmaline in appearance as well as color similarity
The mineral is found in shales and rocks formed at high pressures and temperatures in areas such as the United States, Czechoslovakia, South African diamond mines, Sri Lanka, Brazil, Tanzania, Australia and Zambia
Almandine garnet
The name Almandine is derived from a place in Asia called Alabanda, where garnet stones were formerly cut and polished. Almandine was darker red than blood red; Its structure is iron and aluminum and its red color is due to the element iron. In trade, they are known as “African Garnet or Mozambique”
The specific gravity of almandine is greater than that of pyruvate, and because of their similarity in pure form, they can only be distinguished from each other by measuring their specific gravity. This mineral is found in abundance in metamorphic rocks and in areas such as Sri Lanka, India (quality), Afghanistan, Brazil, Austria and Czechoslovakia. Scottish Germans are opaque and small
Rhodolite garnet
Chemically, rhodolite is a two-to-one ratio between pyruvate and almandine, and is actually a brand to describe many types of purple garnets to medium saturation. The name rhodolite is usually derived from Ceylon ruby, which is derived from the Greek word “rhodonlithos” or rose-like
Spessartine garnet stone
The name of this mineral is taken from the city of Spessart in Germany, where it was first found there. This rare mineral is seen in the form of many cavities and bright orange to pinkish-orange or brownish-yellow
Espartine garnet is very similar to the hasonite handle. Quality examples are found in Germany and Italy, Sri Lanka and Burma, Brazil, the United States, Sweden and the Republic of Malagasy. In Brazil, there are quality samples with dark colors and it is used in jewelry making
Ugrandite category includes
Uvarovite garnet stone
Uvaroite is named after a wealthy Russian politician, Count Uvarove, who researched garnet. This mineral is one of the rarest and best species of garnet, which can only be seen in emerald green due to the presence of chromium. Due to the small size of its crystals, it is less used in jewelry. Its sources include Finland, Italy, Russia, Turkey, the United States and South Africa
Andradite garnet stone
This abundant mineral is named after the Portuguese mineralogist Andra J.B.Andrade. Colors such as yellow, green, brown to black are its characteristics. It is found in Mexico, Switzerland, Italy, Greenland and the United States
According to the color, andradites are divided into three types
Melanite garnet stone
It is a type of black andradite that is used as a substitute for diamonds. Black stones are very rare in the jewelry industry, and melanite is a well-known example of this. Due to titanium, it is replaced by iron compounds and contains black color
Topazolite garnet stone
It is a type of andradite that is seen in yellow to yellow-brown colors. It is called topazolite because of its resemblance to topaz
Demantoid garnet stone
Garnet dementoid is a kind of green andradite with diamond polish and is one of the rarest and most valuable types of garnet family in precious jewelry. Its name is derived from dutch demant meaning diamond. Due to the importance and existence of this type of gemstone in Iran, some time ago we wrote a complete article called Green Dementoid Garnet
It was first found in the Ural Mountains in central Russia and became popular with people, jewelry designers and collectors for its diamond cutting. The most important reserves for quality dementoids are the Ural Mountains. Also found in Zaire and Korea, but of lower quality. Small amounts of it are also found in Iran
Grossular garnet
This opaque gemstone is known for its resemblance to a gooseberry called Gooseberries. Yellow, orange, green and even colorless can be found. It is rarely used in jewelry, but high-quality and semi-transparent types can be considered a gem
There are three types of grossular
Tsavorite garnet stone
Sawrit was first found in 1967 in Kenya’s Tsavo National Park and ranges in color from dark green to light green, and its bright green color in jewelry has a high value and rival due to its color, purity and less chance of breaking in the cut. Emeralds are high quality. The coloring agent in it is vanadium and chromium. This species is found in Kenya, Pakistan, Tanzania and other parts of the world
Hessonite garnet stone
Hesonite is also called Cinnamon or Cinnamon and is seen in brown to orange colors. In Sri Lanka In Sri Lanka, Brazil, Canada, Russia and the United States, there is green garnet in Tanzania and some in Kenya. Pure samples are obtained from Sri Lanka, which is of interest to collectors
Hydrogrossular
Hydrogrosular A type of green or pink grossular with lower hardness of other garnets containing hydroxide water is found in the crystal lattice, opaque and opaque as a compact mass. One reason for its resemblance to the green jade mineral is that it is called “Traswal Jade”. This mineral is mostly found in metaphorical rocks in South Africa, New Zealand and the United States
Leuco Garnet
This type of garnet is colorless and matte in Canada and Mexico and does not matter in the jewelry industry
Which garnet stone is suitable for cutting
The great variety in garnet stone has even made the cutting of any of them different. For example, since the color of Almandine red garnet is very dark, the lower part of the gemstone is emptied to make it lighter. Needle-shaped impurities of rutile have also been observed in some almandines
Jewelry of this mineral is usually used with plates, rosary beads, cabochons and carved on embossed paintings. Most green garnets or those with very small jewels are often kept with the bed as a collection
Garnet reserves in Iran and the world
The largest reserves of garnet are in the United States, India, China and Australia. One of the largest garnet stones discovered in the world in Norway, which weighed 35,000 kg and was 2.3 meters high
In 2009, an exceptional crystal and shite of the largest coarse garnet savory weighing 325.14 carats with quality paint was found in East Africa. In Iran, there is a high potential of garnet mineral that can be seen often in skarn, granite, pegmatite, schist and hornfels and are of grossular, spsartine, almandine and andradite type
Among the most important areas with its reserves, especially the type of valuable dantoid garnet in the country, we can mention Takab, Gabri Mountain, Rafsanjan, Azerbaijan, Kerman Tower Garden, Khorasan, Hamedan, etc. Therefore, if the basic exploration and exploitation management is done correctly, it can cause high employment and profitability in the country.
