Silicate minerals
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Silicates comprise about a quarter of the known minerals and almost 40% of the common ones. The basic unit of structure of all silicate crystals is the tetrahedron. There are four oxygen atoms, one located at each apex of a regular tetrahedron.
The Silicates. Nearly all of the remaining precious stones belong to a great group of mineral species known as the silicates. These are so called because they consist largely of oxide of silicon (the material above referred to under quartz gems).
Silicates (zeolites)
Analcime, Chabazite, Epistilbite, Levyne, Mesolite, Natrolite, Laumontite, Thomsonite, Stilbite.
left - A large boulder, rich in small vesicles, cracked open to reveal a much larger, zeolite-filled cavity.
silicates
Silicates are minerals composed of silicon and oxygen with one or more other elements. Silicates make up about 95% of the Earth's crust.
siliceous
Siliceous means made of or resembling silica.
Silicate: Any of a large group of minerals, forming over 90 percent of the earth's crust, that consist of silicon, oxygen, and one or more metals, (and sometimes hydrogen).
Silicates: Regardless of what other atoms are present (usually one or more metals), gems of this category will have in their chemical formulas some number of Si and O (silicon and oxygen) atoms listed together as a group .
The Silicate Minerals
The great majority of rocks are made of silicate minerals.
Sulfate Minerals
Sulfate minerals form near the Earth's surface.
Silicates
Top
The fundamental constituent of the minerals of the silicate class is the silicate radical (SiO4)4-. This anion group is composed of one silicon atom bonded to four oxygen atoms, which occupy the apices of a regular tetrahedron.
Silicates
Chemistry:
Ca3Al2(SiO4)3 Calcium aluminum silicate (Hessonite contains some iron) ...
SilicateAntigorite
Mg3Si2O5(OH)4
Other names/forms:
Serpentine
Most distinguishing features:
Lustre, colour and habit are indicative.
Silicate Glassy or stony component made up primarily of the element silicon
Strewnfield The area over which a meteorite has fallen
Sulfide Sulfur-containing, as in sulfur-oxide ...
A silicate of zirconium, this mineral occurs in different colours or may be colourless, the latter often being referred to as the poor man's diamond. In fact, zircon tends to be rather dim and is only used for inexpensive jewelry.
A silicate of alumina, iron, and magnesia having a bright blue color and vitreous luster.
Iridescence
Reflection of light off internal features in a gem, giving rise to a rainbow like play of colors.
Copper silicate ore.
Chrysorin
Loose term covering cold working brass with 72-66% copper and 28-34% zinc ...
Silicates. This group of minerals contains SiO44- as the dominant polyanion. In these minerals the Si4+ cation is always surrounded by 4 oxygens in the form of a tetrahedron.
Zirconium Silicate ZrSiO4*
Hardness
7 to 7.5 variable, even within a single specimen. "Low" types 6.5 ...
Topaz is a silicate or "nesosilicate" mineral created from a combination of aluminium and fluorine. It crystallizes in the orthorhombic system and it's crystals are prismatic in form.
Absolute Hardness: 200 ...
Beryl is a silicate mineral group with several varieties of gemstones, including well-known gems like emerald, aquamarine, and morganite, as well as more exotic gems like bixbite, heliodor, and goshenite.
Charoite: A silicate found in Russia it is purple in color and rare.
Chasing: A way to decorate metal by making indentations with a hammer and a punch. It is similar to engraving or embossing and it is the opposite of repoussé.
Fine grained silicate rock produced by metamorphism.
MC -
Miarolitic cavities.
Topaz is nesosilicate having the composition as Al2[(F,OH)2/SiO4.
Hardness
8 ( Mohs) . It is considered quite tough.
Zircon (zircon silicate) is a lustrous gemstone that comes in colors ranging from golden brown to red to violet to blue. Pure zircon is colorless, but most zircon stones are brown.
Epidote: A silicate of alumina, lime, and oxide of iron, or manganese. It is commonly of a yellowish green (pistachio) color.
Essex crystal: See Reverse Crystal jewelry.
metasilicate chains Synonym of inosilicates: Group of silicate minerals that have their tetrahedrons form single or multiple chains, with two oxygen atoms of each tetrahedron part of its neighboring tetrahedron forming long, thin, chains.
Topaz (aluminum silicate fluoride hydroxide) is a very hard gemstone that ranges in color from brown, to yellow to blue to pink. Pink topaz is usually created by irradiating common yellow topaz.
Topaz is a fluorosilicate of aluminum having the relatively simple formula Al2(F,OH)2SiO4. It is a birthstone for November (as is citrine) and the state gem of Texas.
Topaz: A fluosilicate of aluminum that occurs in rhombohedral crystals and is used as a gemstone. Although it is a hard stone, topaz can be susceptible to breaking.
Psilomelane is silicated manganese ore. It has silver lines on a black background and often clear, or Drusy Chalcedony. Psilomelane is pronounced sill-ahm-ah-lane. Sometimes spelled Psillmelane.
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ZrSiO4, Zirconium Silicate. Zircon is not the same material as the artificial gem material Cubic Zirconia (or CZ). Zircon resembles diamond in luster and fire and colorless zircons have been mistaken for diamonds by experienced jewelers.
A calcium aluminum silicate Ca2Al3(O/OH/SiO4/Si2O7) by chemical composition, tanzanite belongs to the zoisite mineral family. It has a hardness of 6.
Dumortierite
A borosilicate mineral, typically blue or violet in colour. Similar in appearance to sodalite and lazurite, it is commonly used to imitate Lapis Lazuli ...
It is essentially a silicate of alumina and soda. Scapolite is also called Wernerite, named after the German Geologist A.G. Werner. Scapolite is typically an altered form of plagioclase feldspars found in metamorphic rocks.
Topaz is an alumina silicate with a hardness of 8 on the Mohs scale, making it one of the harder gems - but it shares the quality of cleavage with its cousin the diamond.
Beryllium-aluminium-silicate or Beryl is widely used as a gem material. In its pure form (also known as Goshenite), beryl is colourless. However, stored foreign substances give it different colours and different names.
Axinite is a boro-silicate of aluminum and calcium. It is used only as a mineral specimen and not in jewelry.
Garnets are any of a group of semi-precious silicate stones that range in color from red to green (garnets occur in all colors but blue).
A white or grey mineral composed of Calcium Boro-silicate Hydroxide. Howlite is easily dyed various colors and with its attractive grey matrix, is often dyed azure blue and used as a turquoise look-alike. Howlite has a hardness of 3.5.
Iolite ...
2, Chain Silicates. John Wiley and Sons, New York.
DelRe N. (1992) Gem Trade Lab notes: Repaired jadeite. Gems & Gemology, Vol. 28, No. 3, pp. 193-194.
Ehrmann M.L. (1958) A new look in jade. Gems & Gemology, Vol. 9, No. 5, pp.
Topaz (aluminum fluorite silicate) is the hardest of the silicate minerals, due to strong chemical bonds within the stone.
This olivine variety is composed of magnesium iron silicate. Peridot (pronounced PEAR-ih-doh or PEAR-ih-dot) is created under great temperatures and pressures deep within the Earth, and sometimes is extruded in basaltic lavas.
Jackets are often used to embellish solitaire rings or simple stud earrings Jade: One of two metamorphic rocks composed of different silicate minerals, Nephite or Jadeite.
Silicates - Mineral containing silicon and oxygen, along with other elements.
Skarn - A contact metamorphic rock, often containing well-formed crystals of silicate and other minerals.
From a chemical-mineralogical point of view, emeralds are beryllium-aluminium-silicates with a good hardness of 7.
Garnet: A family of stones having many varieties differing in color and in their constituents, but all are silicates with the same isometric crystallization and conforming to the same general chemical formula.
Tanzanite is the gem name for the silicate mineral Zoisite. Although this fairly common mineral has long been known to geologitsts, the gem form of this mineral was only discovered in 1967.
The lithium in kunzite’s chemical composition, lithium aluminum silicate, along with trace amounts of manganese, gives it the wonderful pink colors that complement both autumn and spring wardrobes.
Sugilite (also known as luvulite) is a relatively rare pink to purple cyclosilicate mineral with the complex chemical formula: KNa2(Fe,Mn,Al)2Li3Si12O30. Sugilite crystallizes in the hexagonal system with prismatic crystals.
(This is the last edition of Dana that included silicates. Dana's 7th edition never was completed and is divided into 3 volumes making it more difficult to use.
Sillimanite (aluminum silicate, Al2 SiO5) is a transparent to translucent mineral that ranges in color from white to gray to brownish to greenish.
Danburite (Calcium borosilicate - CaB2Si2O8) is a clear to white silicate mineral whose orthorhombic crystals are transparent to translucent (danburite can also be yellow, greenish, or brown); it resembles topaz.
It was not until the mid 18th century that the name was assigned to the aluminum fluor-silicate that we know it as now. Even in the 16th century Cellini described a - most probably - yellow sapphire as "topaz".
Sillimanite is chemically named Aluminum Silicate and it shows polymorphism with minerals like Kyanite and Andalusite. A mineral which shares similar chemistry with other minerals but differs in their crystalline structure, is called a polymorph.
Its composition is potassium aluminosilicate (KAlSi3O8), and is a type of feldspar (a green variety of microcline). Amazonite is usually set as a cabochon (since it breaks easily if faceted).
Beryl Beryl (beryllium aluminum cyclosilicate) is the name of a family of stones that includes Emerald, Bixbite, Aquamarine, Morganite, Goshenite, Golden Beryl, Heliodor, and Honey Yellow Beryl.
Topaz is composed of silicate of aluminum containing fluorine and hydroxyl. Gem quality topaz is mostly found in pegmatite dykes. Topaz crystalstypically form prisms with a diamond shaped cross section and a pyramidal top.
Chemically speaking, tourmaline is a complex aluminum and boron silicate mineral. Colors are red, pink, blue, green, yellow, violet, and black; sometimes it is colorless.
Chemical composition -- The garnets comprise a family of complex silicates with widely varying chemical composition but similar structures.
Peridot is the best known gem variety of olivine, a species name for a series of magnesium-iron rich silicate minerals. This bright yellow-green to green gemstone has caught the fancy of humans for thousands of years.
Chemical Composition: sodium aluminum silicate (jadeite), calcium magnesium aluminum silicate, with some iron (nephrite)
Crystal System: monoclinic (jadeite and nephrite)
Hardness: 7 (jadeite), 6.5 (nephrite)
Specific Gravity: 3.3-3.
 See also: Silica, Crystal, Mineral, Stone, Color
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