corundum

Amethyst is a violet or purple variety of quartz often used as an ornament. The name is generally said to be derived from the Greek a, "not," and methuskein, "to intoxicate," expressing the old belief that the stone protected its owner from drunkenness. It was held that wine drunk out of a cup of amethyst would not intoxicate. However, the word may probably be a corruption of an Oriental name for the stone. In the 20th century, the color of amethyst was attributed to the presence of manganese. However, since it is ...

Including:

• Amethyst - Value
• Amethyst - Amethyst in folklore and astrology

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Adamantine is a mineral, often referred to as adamantine spar. It is a silky brown form of corundum. It has a Mohs rating of 9. Adamantine is also used as an adjective to refer to non-metallic, brilliant light reflecting and transmitting properties, known as adamantine lustre. Diamond is the best known material to be described as having adamantine listre, although anglesite, cerussite and corundum in ...

Including:

• Adamantine - In mythology and fiction

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The mineral or gemstone chrysoberyl, not to be confused with beryl, is an aluminate of beryllium with the formula BeAl2O4. Chrysoberyl is transparent to translucent and sometimes opalescent. An interesting feature of uncut crystals of chyrsoberyl are the cyclic twins called trillings. These twinned crystals have a hexagonal appearance, but are the result of a triplet of twins with each "twin" taking up 120 degrees of the cyclic trilling. The word chrysoberyl is derived from the Greek words meaning golden a ...

Including:

• Chrysoberyl - Occurrence
• Chrysoberyl - Alexandrite variety
• Chrysoberyl - Cymophane variety

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A knife is a sharp-edged hand tool used for cutting. A knife usually consists of a blade, commonly less than 12 inches (30cm) in length, attached to a handle. The blade of a knife is usually pointed and may have one or two cutting edges. Knives have been used as tools and weapons since the Stone Age. The first knives were flint or other rock, chipped or ground to an edge, sometimes with a hand ...

Including:

• Knife - Anatomy of a knife
• Knife - Blades
• Knife - Types of knives
• Knife - Form
• Knife - Function
• Knife - Using knives
• Knife - Sharpening
• Knife - Mechanical consideration of the strength of sharpened edges and rolled-over knife edges
• Knife - Legal considerations
• Knife - In the USA
• Knife - In the UK
• Knife - Knife modifications
• Knife - Knife superstitions

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Aluminium or aluminum (Symbol Al) (see the spelling section below) is a silvery and ductile member of the poor metal group of chemical elements. Its atomic number is 13. Aluminium is found primarily as the ore bauxite and is remarkable for its resistance to oxidation (due to the phenomenon of passivation), its strength, and its light weight. Aluminium is used in many industries to make millions of different products and is very important to the world economy. Structural components made from aluminium are vital to the aer ...

Including:

• Aluminium - Properties
• Aluminium - Applications
• Aluminium - Engineering use
• Aluminium - History
• Aluminium - Natural occurrence
• Aluminium - Isotopes
• Aluminium - Clusters
• Aluminium - Precautions
• Aluminium - Spelling
• Aluminium - Etymology / Nomenclature history
• Aluminium - Present day spelling
• Aluminium - Chemistry
• Aluminium - Oxidation state 1
• Aluminium - Oxidation state 2
• Aluminium - Oxidation state 3
• Aluminium - Aluminium in popular culture

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Vanadium is a chemical element in the periodic table that has the symbol V and atomic number 23. A rare, soft and ductile element, vanadium is found combined in certain minerals and is used mainly to produce certain alloys. Vanadium - Notable characteristics. Vanadium is a soft and ductile, gray-white metal. It has good resistance to corrosion by alkalis, sulfuric and hydrochloric acid. It oxidizes readily at about 933 K. Vanadium has good structural strength and a low fission neutron cross section, ...

Including:

• Vanadium - Notable characteristics
• Vanadium - Applications
• Vanadium - History
• Vanadium - Biological role
• Vanadium - Occurrence
• Vanadium - Isolation
• Vanadium - Compounds
• Vanadium - Isotopes
• Vanadium - Precautions

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In mineralogy, shape and size give rise to descriptive terms applied to the typical appearance, or habit of crystals. The many terms used by mineralogists to describe crystal habits are useful in communicating what specimens of a particular mineral often look like. Recognising numerous habits helps a mineralogist to identify a large number of minerals. Some habits are distinctive of certain minerals, although most minerals exhibit many differing habits which are influenced by certain factors. Crystal habit may mislead the inexperienced as a ...

Including:

• Crystal habit - List of crystal habits

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Ammolite is a rare and valuable opal-like organic gemstone found primarily along the eastern slopes of the Rocky Mountains of the United States and Canada. It is made of the fossilized shells of ammonites, which in turn are composed primarily of aragonite, the same mineral that makes up nacreous pearls. It is one of the three biogenic gemstones, the other two being amber and pearl.1 In 1981, ammolite was given official gemstone status by the World Jewellery Confederation, the same year commercial mining of ammolite began. In 2004 it was designated th ...

Including:

• Ammolite - Properties
• Ammolite - Formation occurrence and extraction
• Ammolite - Gemstone quality
• Ammolite - Treatments
• Ammolite - Imitations
• Ammolite - Use in jewelry
• Ammolite - Notes

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An abrasive is usually a material that is used to smooth, machine, or, in some cases, roughen another softer material through extensive rubbing. Some common examples of abrasive minerals and objects are: Coated abrasives Aluminum Oxide Zirconia Alumina Silicon Carbide Ceramic Borazon or Cubic Boron Nitride (CBN) Diamond dust Emery (mineral) (impure corundum) Grinding wheel Powdered glass Pumice dust ...

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Diamond is one of the two best known forms (or allotropes) of carbon, whose hardness and high dispersion of light make it useful for industrial applications and jewelry (the other equally well known allotrope is graphite). Diamonds are specifically renowned as a mineral with superlative physical qualities - they make excellent abrasives because they can only be scratched by other diamonds, which also means they hold a polish extremely well and retain luster. About 130 million carats (26,000 kg) are mined annually ...

Including:

• Diamond - Material properties
• Diamond - Mechanical properties
• Diamond - Electromagnetic properties
• Diamond - Media
• Diamond - Natural history
• Diamond - Formation
• Diamond - Surfacing
• Diamond - Gemological characteristics
• Diamond - Carat
• Diamond - Clarity
• Diamond - Color
• Diamond - Cut
• Diamond - Cleaning
• Diamond - History
• Diamond - Record-holding diamonds
• Diamond - The diamond industry
• Diamond - Gem diamond industry
• Diamond - Industrial diamond industry
• Diamond - Diamond supply chain
• Diamond - Synthetics simulants and enhancements
• Diamond - Symbolism

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Aluminium oxide or aluminum oxide is a chemical compound of aluminium and oxygen with the chemical formula Al2O3. It is also commonly referred to as alumina in the mining, ceramic, and materials science communities. Alumina is generally available in two concentrations: 99.5% and 96%. Aluminium oxide is responsible for metallic aluminium's resistance to weathering. Metallic aluminium is very reactive with atmospheric oxygen, and a thin passivation layer of aluminium oxide quickly forms on any ...

Including:

• Aluminium oxide - Industrial Fabrication Process

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Gibbsite, Al(OH)3, is an important ore of aluminium and is one of three minerals that make up the rock bauxite. Bauxite is often thought of as a mineral but is really a rock composed of aluminium oxide and hydroxide minerals such as gibbsite, boehmite (AlO(OH)), and diaspore (HAlO2), as well as clays, silt, and iron oxides and hydroxides. Bauxite is a laterite, a rock formed from intense weathering environments such as foun ...

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Sapphire is the single-crystal form of aluminium oxide (Al2O3), a mineral known as corundum. It can be found naturally as gemstones or manufactured in large crystal boules for a variety of applications. Sapphire - Sapphire gems. Sapphire is any gemstone-quality corundum. (The red variety of corundum is also known as ruby.) When color is not specified, sapphire refers to the blue variety. Pink, yellow, green, white, and parti-color (multi-colored) sapphires are oft ...

Including:

• Sapphire - Sapphire gems
• Sapphire - Synthetic sapphire for non-gemstone applications

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Ruby is a red gemstone, a variety of the mineral corundum (aluminium oxide) in which the color is caused mainly by chromium. Its name originates from ruber, Latin for red. Natural rubies are exceptionally rare, though artificial ones (sometimes called created ruby) can be manufactured which are comparatively inexpensive. Rubies are mined in Africa, Asia, Australia and Greenland. They are most often found in Myanmar, Sri Lanka and Thailand, though they have also been found in Montana and South Carolina. Sometimes s ...

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A gemstone is a mineral, rock (as in lapis lazuli) or petrified material that when cut or faceted and polished is collectible or can be used in jewellery. Others are organic, such as amber (fossilised tree resin) and jet (a form of coal). Some beautiful gemstones are too soft or too fragile to be used in jewelry, for example, single-crystal rhodochrosite, but are exhibited in museums and are sought by collectors. Gemstone - Characteristics and classification. Gemstones are described by gemologists using tec ...

Including:

• Gemstone - Characteristics and classification
• Gemstone - Value
• Gemstone - Factors Influencing Esteem
• Gemstone - Synthetic and artificial gemstones
• Gemstone - Gemstone list

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Silicon carbide (SiC), also known as moissanite, is a ceramic compound of silicon and carbon. Most silicon carbide is man-made for use as an abrasive (when it is often known by the trademark carborundum), or more recently as a semiconductor and moissanite gemstones. The simplest manufacturing process is to combine sand and carbon at a high temperature, between 1600 °C and 2500 °C. Alpha silicon carbide (α-SiC) is most common, and is formed at temperatures >2000°C. Alpha SiC has the typical hexagonal ...

Including:

• Silicon carbide - Uses
• Silicon carbide - Semiconductor
• Silicon carbide - Structural material
• Silicon carbide - Astronomy
• Silicon carbide - Grit
• Silicon carbide - Disc brake
• Silicon carbide - Diesel Particulate Filter
• Silicon carbide - Cutting Tools
• Silicon carbide - Culture
• Silicon carbide - Patents and Trademarks

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Chromite, iron magnesium chromium oxide: (Fe,Mg)Cr2O4, is an oxide mineral belonging to the spinel group. Magnesium is always present in variable amounts, also aluminium and iron substitute for chromium. Chromite is found in peridotite and other layered ultramafic intrusive rocks and also found in metamorphic rocks such as serpentinites. Ore deposits of chromite form as early magmatic differentiates. It is commonly associated with olivine, magnetite, serpentine, and corundum. The vast Bushveld igneous comp ...

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Bellary is a city in Bellary District in Karnataka state, India. Bellary - History. Bellary takes its name from the word Balari which refers to goddess Durugamma as this goddess had manifested herself in the town. Some of the events in the great epic Ramayana are related to this historical place. It is said that Rama while searching for Sita met Sugreeva and Hanuman at a place near Hampi, the celebrated capital of the Vijayanagara empire. The history speaks volumes about significant role it a ...

Including:

• Bellary - History
• Bellary - Bellary District

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Pneumoconiosis is a lung condition caused by the inhalation of dust, characterized by formation of nodular fibrotic changes in lungs. Many substances can cause pneumoconiosis including asbestos, silica, talc and metals. Depending on the type of dust, variants of the disease are considered. For example there are silicosis, also known as grinders' disease; and pneumosilicosis, which is caused by the inhalation of the dust of stone, sand, or flint containing silica. Because many common minerals co ...

Including:

• Pneumoconiosis - Incidents
• Pneumoconiosis - Types
• Pneumoconiosis - Bauxite pneumoconiosis
• Pneumoconiosis - Black lung disease

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The Italian city states, especially Genoa, Pisa, and Venice, had been interested in the islands of the Aegean long before the Fourth Crusade. There were Italian trading colonies in Constantinople and Italian pirates frequently attacked settlements in the Aegean in the 12th century. After the collapse of the Byzantine Empire in 1204, in which the Venetians played a major role, Venetian interests in the Aegean could be more thoroughly realized. The Duchy of the Archipelago was created in 1207 by Marco Sanudo, a participant in the Crusad ...

See also:

Duchy of the Archipelago, Duchy of the Archipelago - Background and foundation, Duchy of the Archipelago - Administration and economics, Duchy of the Archipelago - Later history, Duchy of the Archipelago - Collapse and Ottoman conquest, Duchy of the Archipelago - Other Venetian territories in the Aegean, Duchy of the Archipelago - Dukes of the Archipelago, Duchy of the Archipelago - Sanudo dynasty, Duchy of the Archipelago - Crispo dynasty, Duchy of the Archipelago - Pretenders of the Duchy of the Archipelago Naxos Islands

Read more here: » Duchy of the Archipelago: Encyclopedia II - Duchy of the Archipelago - Background and foundation