Tampilkan postingan dengan label gemstone spesification. Tampilkan semua postingan
Tampilkan postingan dengan label gemstone spesification. Tampilkan semua postingan
Thulite (sometimes called rosaline) is an opaque, massive pink manganese-bearing variety of the mineral zoisite. Manganese substitutes for calcium in the structure with up to two percent Mn2+. Thulite is often mottled with white calcite and occurs as veins and fracture fillings transecting many types of rock. In mineralogical literature, thulite may sometimes refer to any pink zoisite. Clinothulite is the manganese bearing variety of monoclinic clinozoisite.
Thulite was first discovered at a place called Sauland in Telemark, Norway in 1820. It is named after the mythical island of Thule in the belief that the island is Norway. Thulite is used as a gemstone and carving material in the manufacture of jewellery and ornamental objects.
Thulite is also found in the Austrian Tyrol, in Mitchell County, North Carolina, and in Western Australia. A new, more recent find of high quality thulite was discovered near Riverside in Okanogan County, Washington, USA.
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Thulite was first discovered at a place called Sauland in Telemark, Norway in 1820. It is named after the mythical island of Thule in the belief that the island is Norway. Thulite is used as a gemstone and carving material in the manufacture of jewellery and ornamental objects.
Thulite is also found in the Austrian Tyrol, in Mitchell County, North Carolina, and in Western Australia. A new, more recent find of high quality thulite was discovered near Riverside in Okanogan County, Washington, USA.
Thulite Properties
Tanzanite is the blue/purple variety of the mineral zoisite (a calcium aluminium hydroxy silicate) which was discovered in the Mererani Hills of Northern Tanzania in 1967, near the city of Arusha and Mount Kilimanjaro. It is used as a gemstone. Tanzanite is noted for its remarkably strong trichroism, appearing alternately sapphire blue, violet and burgundy depending on crystal orientation. Tanzanite can also appear differently when viewed under alternate lighting conditions.
The blues appear more evident when subjected to fluorescent light and the violet hues can be seen readily when viewed under incandescent illumination. Tanzanite in its rough state is usually a reddish brown color. It requires artificial heat treatment to 600 °C in a gemological oven to bring out the blue violet of the stone. Tanzanite is a rare gem. It is found mostly in the foothills of Mount Kilimanjaro. The mineral is named after Tanzania, the country in which it was discovered.
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The blues appear more evident when subjected to fluorescent light and the violet hues can be seen readily when viewed under incandescent illumination. Tanzanite in its rough state is usually a reddish brown color. It requires artificial heat treatment to 600 °C in a gemological oven to bring out the blue violet of the stone. Tanzanite is a rare gem. It is found mostly in the foothills of Mount Kilimanjaro. The mineral is named after Tanzania, the country in which it was discovered.
Tanzanite Properties
Zoisite occurs in a number of varieties, the most sought-after being tanzanite, a variety colored sapphire-blue by the presence of vanadium. Tanzanite crystals have distinct pleochriosm, showing either purple, blue or slate-grey depending on the angle they are viewed from. There may also be a slight color change in incandescent light (such as that from a light blub), when stones may appear more violet. A massive green variety of zoisite, containing rubies and occasionally dark horn-blende inclusions, may be polished, carved, or tumbled to make ornaments or an attractive decorative stone. Thulite, a massive, pinkish red variety colored by manganese, is also polished or carved to make small ornaments. Tanzanite has been confused with sapphire, and thulite with rhodonite. Some heating of zoisite varieties may enhance their colour.
Tanzanite was first found in Tanzania (hence the name). Yellow and green zoisite occurs in Tanzania and Kenya. Thulite is found in Norway, Austria, western Australia, Italy and North Carolina (USA).
Discovered by Baron von Zois in the Sau-Alp mountains of Austria, zoisite was first called saualpite.
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Tanzanite was first found in Tanzania (hence the name). Yellow and green zoisite occurs in Tanzania and Kenya. Thulite is found in Norway, Austria, western Australia, Italy and North Carolina (USA).
Discovered by Baron von Zois in the Sau-Alp mountains of Austria, zoisite was first called saualpite.
Zoisite Properties
Zoisite occurs in a number of varieties, the most sought-after being tanzanite, a variety colored sapphire-blue by the presence of vanadium. Tanzanite crystals have distinct pleochriosm, showing either purple, blue or slate-grey depending on the angle they are viewed from. There may also be a slight color change in incandescent light (such as that from a light blub), when stones may appear more violet. A massive green variety of zoisite, containing rubies and occasionally dark horn-blende inclusions, may be polished, carved, or tumbled to make ornaments or an attractive decorative stone. Thulite, a massive, pinkish red variety colored by manganese, is also polished or carved to make small ornaments. Tanzanite has been confused with sapphire, and thulite with rhodonite. Some heating of zoisite varieties may enhance their colour.
Tanzanite was first found in Tanzania (hence the name). Yellow and green zoisite occurs in Tanzania and Kenya. Thulite is found in Norway, Austria, western Australia, Italy and North Carolina (USA).
Discovered by Baron von Zois in the Sau-Alp mountains of Austria, zoisite was first called saualpite.
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Tanzanite was first found in Tanzania (hence the name). Yellow and green zoisite occurs in Tanzania and Kenya. Thulite is found in Norway, Austria, western Australia, Italy and North Carolina (USA).
Discovered by Baron von Zois in the Sau-Alp mountains of Austria, zoisite was first called saualpite.
Zoisite Properties
Zircon is most famous for its colorless stones, which closely resemble diamonds and have been used both intentionally and mistakenly in their place. Although colorless when pure, impurities will produce yellow, orange, blue, red, brown and green varieties. Brown stones from Thailand, Vietnam and Kampuchea are usually heat-treated to change them into the colorless or blue stones popular in jewelery. Blue stones that revert to brown will regain the blue if reheated. Blue zircon reheated in the presence of oxygen will change to golden-yellow. Zircon may be distinguished from diamond by its double refraction and by wear and tear on its facet edges. It has been imitated by both colorless glass and synthetic spinel. Some zircon contains radioactive thorium and uranium, which eventually break down the crystal structure. Decayed stones are known as “low” zircon, with a “metamict” structure; undamaged material is “high” zircon.
Gem-quality crystals are usually found as pebbles in alluvial deposits. Sri Lanka has been a source of gem material for over 2,000 years; other localities include Burma, Thailand, Cambodia, Vietnam, Kampuchea, Australia, Brazil, Nigeria, Tanzania, and France.
Zircon was believed to provide the wearer with wisdom, honor, and riches and loss of lustre was said to warn of danger. The name is from the Arabic zargun, which derives from the Persian for “gold color”.
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Gem-quality crystals are usually found as pebbles in alluvial deposits. Sri Lanka has been a source of gem material for over 2,000 years; other localities include Burma, Thailand, Cambodia, Vietnam, Kampuchea, Australia, Brazil, Nigeria, Tanzania, and France.
Zircon was believed to provide the wearer with wisdom, honor, and riches and loss of lustre was said to warn of danger. The name is from the Arabic zargun, which derives from the Persian for “gold color”.
Zircon Properties
Yttrium aluminium garnet (YAG) is a synthetic crystalline material of the garnet group.
YAG for a period was used in jewelry as a diamond and other gemstone simulant. Colored variants and their doping elements include: green (chromium), blue (cobalt), red (manganese), yellow (titanium), purple (neodymium), pink, and orange. As faceted gems they are valued (as synthetics) for their clarity, durability, high refractive index and dispersion. The critical angle of YAG is 33 degrees. YAG cuts similar to natural garnet, with polishing being performed with alumina or diamond (50,000 or 100,000) on common polishing laps. YAG has low heat sensitivity.
As a synthetic gemstone YAG has numerous varietal and trade names, as well as a number of misnomers. Synonymous names include: alexite, amamite, circolite, dia-bud, diamite, diamogem, diamonair, diamone, diamonique, diamonite, diamonte, di'yag, geminair, gemonair, kimberly, Linde simulated diamond, nier-gem, regalair, replique, somerset, triamond, YAIG, and yttrium garnet. Production for the gem trade decreased after the introduction of synthetic cubic zirconia; as of 1995 there was little production. Some demand exists as synthetic garnet, and for designs where the very high refractive index of cubic zirconia is not desirable.
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YAG for a period was used in jewelry as a diamond and other gemstone simulant. Colored variants and their doping elements include: green (chromium), blue (cobalt), red (manganese), yellow (titanium), purple (neodymium), pink, and orange. As faceted gems they are valued (as synthetics) for their clarity, durability, high refractive index and dispersion. The critical angle of YAG is 33 degrees. YAG cuts similar to natural garnet, with polishing being performed with alumina or diamond (50,000 or 100,000) on common polishing laps. YAG has low heat sensitivity.
As a synthetic gemstone YAG has numerous varietal and trade names, as well as a number of misnomers. Synonymous names include: alexite, amamite, circolite, dia-bud, diamite, diamogem, diamonair, diamone, diamonique, diamonite, diamonte, di'yag, geminair, gemonair, kimberly, Linde simulated diamond, nier-gem, regalair, replique, somerset, triamond, YAIG, and yttrium garnet. Production for the gem trade decreased after the introduction of synthetic cubic zirconia; as of 1995 there was little production. Some demand exists as synthetic garnet, and for designs where the very high refractive index of cubic zirconia is not desirable.
Yttrium Aluminium Garnet Properties
One of the first gemstones to be mined, turquoise has long been prized for its intense color, which varies from sky-blue to green, depending on the quantities of iron and copper within it. Turquoise is commonly found in microcrystalline, massive form, usually as encrustations, in veins, or as nodules. It is opaque to semi-translucent, light and very fragile, with conchoidal fracture. Some material is very porous, leading to fading and cracking, so it may be impregnated with wax or resin to maintain its appearance.
Sky blue turquoise from Iran is generally regarded as the most desirable; but in Tibet a greener variety is preferred. Localities in Mexico and United States produce a greener, more porous material that tends to fade more quickly. Other localities include the former USSR, Chile, Australia, Turkistan and Cornwall (England).
Turquoise has been thought to warn the wearer of danger or illness by changing color. It has been imitated by stained howlite, fossil bone or tooth, limestone, chalcedony, glass, and enamel. In 1972, an imitation turquoise was produced in France by Gilson.
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Sky blue turquoise from Iran is generally regarded as the most desirable; but in Tibet a greener variety is preferred. Localities in Mexico and United States produce a greener, more porous material that tends to fade more quickly. Other localities include the former USSR, Chile, Australia, Turkistan and Cornwall (England).
Turquoise has been thought to warn the wearer of danger or illness by changing color. It has been imitated by stained howlite, fossil bone or tooth, limestone, chalcedony, glass, and enamel. In 1972, an imitation turquoise was produced in France by Gilson.
Turquoise Properties
Tugtupite was first discovered in 1960 in Greenland, where it is craved for jewellery. Colors include dark red to bright pink, and shades of orange. It may look mottled. When it is placed in the dark, the paler parts of the rock fade to white, but exposure to light restores the color.
Tugtupite is found as massive opaque material in pegmatite veins. It also occurs in northern Russia.
The name derives from its occurrence in Tugtup, Greenland, and means reindeer stone.
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Tugtupite is found as massive opaque material in pegmatite veins. It also occurs in northern Russia.
The name derives from its occurrence in Tugtup, Greenland, and means reindeer stone.
Tugtupite Properties
Yellow and green is the most common of all tourmaline color varieties, but emerald-green is much rarer and more valuable. Indeed, until the 18th century it was often confused with emerald.
Emerald-green stones are found in Brazil, Tanzania, and Namibia; fibrous yellow material occurs in Sri Lanka.
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Emerald-green stones are found in Brazil, Tanzania, and Namibia; fibrous yellow material occurs in Sri Lanka.
Yellow and Green Tourmaline Properties
Tourmaline crystals with a pink centre and a green rim, or vice-versa, are called watermelon tourmaline, because their coloring is similar to the pink flesh and green rind of a watermelon. Many other tourmalines are made up of two or more colors, individual crystals containing up to 15 different colors or shades.
Watermelon tourmaline is found in South Africa, East Africa, Brazil and in a many other localities.
Parti and multi-colored tourmaline is carved or cut and polished to show off the different colors to best effect.
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Watermelon tourmaline is found in South Africa, East Africa, Brazil and in a many other localities.
Parti and multi-colored tourmaline is carved or cut and polished to show off the different colors to best effect.
Watermelon Tourmaline Properties
Schorl is the black , iron-rich form of tourmaline, and is very common. The opaque, prismatic crystals may be several metres in length.
Schorl is found in pegmatites. During the Victorian era, black tourmaline was widely used for mourning jewellery, but today it has little, if any, value as a gemstone.
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Schorl is found in pegmatites. During the Victorian era, black tourmaline was widely used for mourning jewellery, but today it has little, if any, value as a gemstone.
Schorl Properties
Members of the tourmaline family of minerals have the same basic crystal structure, but occur in many colors. Rubellite (from the Latin for red) is the name given to the pink or red variety, with ruby-red stones the most highly prized. Rubellite crystals are striated, with a triangular cross-section and a rounded outline. They may also occur with a fibrous habit, and show a cat's-eye when cut in cabochon.
Russian pink and red tourmaline occurs in weathered granites. Other sites include Madagascar, United States, Brazil, Burma, and East Africa.
The specific gravity of tourmaline varies with color dark red has a higher S.G. than pink.
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Russian pink and red tourmaline occurs in weathered granites. Other sites include Madagascar, United States, Brazil, Burma, and East Africa.
The specific gravity of tourmaline varies with color dark red has a higher S.G. than pink.
Rubellite Properties
Dark blue tourmaline is called indicolite or, occasionally, indigolite. Indicolite is often heat-treated to lighten its color and produce a more attractive stone.
An important source for indicolite is Siberia (Russia), where it occurs in yellow clays formed from weathered granites. Fine, bright blue tourmaline has recently been found in Paraiba, Brazil. Other localities include Madagascar and United States.
A lilac to violet-blue or reddish blue variety (first found in Russia) is known as siberite.
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An important source for indicolite is Siberia (Russia), where it occurs in yellow clays formed from weathered granites. Fine, bright blue tourmaline has recently been found in Paraiba, Brazil. Other localities include Madagascar and United States.
A lilac to violet-blue or reddish blue variety (first found in Russia) is known as siberite.
Indicolite Properties
Dravite is a very dark colored (usually brown) form of tourmaline, rich in magnesium. It is possible to lighten the color by heat treatment. Dravite shows strong dichroism, and should therefore be cut with the table facet parallel to the length of the crystal in order to show a lighter and more attractive color.
Dravite can occur as single crystals, or as parallel or radiating groups. Brown tourmaline and yellow tourmaline occur together in the gem gravels of Sri Lanka. It is also found in the United States, Canada, Mexico, Brazil and Australia.
The name "dravite" is derived from the district of Drave, in Austria.
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Dravite can occur as single crystals, or as parallel or radiating groups. Brown tourmaline and yellow tourmaline occur together in the gem gravels of Sri Lanka. It is also found in the United States, Canada, Mexico, Brazil and Australia.
The name "dravite" is derived from the district of Drave, in Austria.
Dravite Properties
This particularly rare, colorless stone is a variety of elbaite, a member of the tourmaline group. It does not show the strong dichroism characteristic of most tourmaline varieties and therefore can be cut with the table facet either parallel or perpendicular to the lenght of the crystal. Colorless tourmaline may also be produced by applying heat to light pink tourmalines.
Achroite occurs with colored tourmalines in the pegmatites of Madagascar and Pala (in California in United States),
Achroite is named after the Greek work achroos, meaning "without colour".
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Achroite occurs with colored tourmalines in the pegmatites of Madagascar and Pala (in California in United States),
Achroite is named after the Greek work achroos, meaning "without colour".
Achroite Properties
