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Ekanite
Ekanite is an uncommon silicate mineral with chemical formula or . It is a member of the steacyite group. It is among the few gemstones that are naturally radioactive. Most ekanite is mined in Sri Lanka, although deposits also occur in Russia and North America. Clear and well-colored stones are rare as the radioactivity tends to degrade the crystal matrix over time in a process known as metamictization. The type locality is Eheliyagoda, Ratnapura District, Sabaragamuwa Province, Sri Lanka, where it was first described in 1955 by F. L. D. Ekanayake, a Sri Lankan scientist, and it is named after him. In Sri Lanka the mineral specimens occur as detrital pebbles. In the Tombstone Mountains of Yukon, Canada, the mineral is found in a syenitic glacial erratic boulder. In the Alban Hills of Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metamictization
Metamictisation (sometimes called metamictization or metamiction) is a natural process resulting in the gradual and ultimately complete destruction of a mineral's crystal structure, leaving the mineral amorphous. The affected material is therefore described as metamict. Certain minerals occasionally contain interstitial impurities of radioactive elements, and it is the alpha radiation emitted from those compounds that is responsible for degrading a mineral's crystal structure through internal bombardment. The effects of metamictisation are extensive: other than negating any birefringence previously present, the process also lowers a mineral's refractive index, hardness, and its specific gravity. The mineral's colour is also affected: metamict specimens are usually green, brown or blackish. Further, metamictisation diffuses the bands of a mineral's absorption spectrum. Curiously and inexplicably, the one attribute which metamictisation does not alter is dispersion. All metam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metamict
Metamictisation (sometimes called metamictization or metamiction) is a natural process resulting in the gradual and ultimately complete destruction of a mineral's crystal structure, leaving the mineral amorphous. The affected material is therefore described as metamict. Certain minerals occasionally contain interstitial impurities of radioactive elements, and it is the alpha radiation emitted from those compounds that is responsible for degrading a mineral's crystal structure through internal bombardment. The effects of metamictisation are extensive: other than negating any birefringence previously present, the process also lowers a mineral's refractive index, hardness, and its specific gravity. The mineral's colour is also affected: metamict specimens are usually green, brown or blackish. Further, metamictisation diffuses the bands of a mineral's absorption spectrum. Curiously and inexplicably, the one attribute which metamictisation does not alter is dispersion. All metamict mater ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicate Mineral
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually considered a silicate mineral. Silica is found in nature as the mineral quartz, and its polymorphs. On Earth, a wide variety of silicate minerals occur in an even wider range of combinations as a result of the processes that have been forming and re-working the crust for billions of years. These processes include partial melting, crystallization, fractionation, metamorphism, weathering, and diagenesis. Living organisms also contribute to this geologic cycle. For example, a type of plankton known as diatoms construct their exoskeletons ("frustules") from silica extracted from seawater. The frustules of dead diatoms are a major constituent of deep ocean sediment, and of diatomaceous earth. General structure A silicate mineral is generally ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tombstone Territorial Park
Tombstone Territorial Park is a territorial park in the Yukon, one of three territories in Canada. It is in central Yukon, near the southern end of the Dempster Highway, stretching from the 50.5 to the 115.0 kilometre marker. The park protects over 2100 square kilometres of rugged peaks, permafrost landforms and wildlife, including sections of the Blackstone Uplands and the Ogilvie Mountains. The Park is named for Tombstone Mountain's resemblance to a grave marker. The area is geologically unique and ecologically diverse. It is bisected by the divide separating waters flowing into the Yukon River and eventually the Bering Sea from those flowing into the Mackenzie River and eventually the Beaufort Sea. The divide is part of an igneous belt of granitic and syenitic rock, known as the Cretaceous Tombstone Suite, that stretches from Fairbanks, Alaska, to the Ross River. Multiple glaciations intruded into the region from the east, separating it from areas to the north and west, k ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetragonal Minerals
In crystallography, the tetragonal crystal system is one of the 7 crystal systems. Tetragonal crystal lattices result from stretching a cubic lattice along one of its lattice vectors, so that the cube becomes a rectangular prism with a square base (''a'' by ''a'') and height (''c'', which is different from ''a''). Bravais lattices There are two tetragonal Bravais lattices: the primitive tetragonal and the body-centered tetragonal. The base-centered tetragonal lattice is equivalent to the primitive tetragonal lattice with a smaller unit cell, while the face-centered tetragonal lattice is equivalent to the body-centered tetragonal lattice with a smaller unit cell. Crystal classes The point groups that fall under this crystal system are listed below, followed by their representations in international notation, Schoenflies notation, orbifold notation, Coxeter notation and mineral examples.Hurlbut, Cornelius S.; Klein, Cornelis, 1985, ''Manual of Mineralogy'', 20th ed., p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phyllosilicates
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually considered a silicate mineral. Silica is found in nature as the mineral quartz, and its polymorphs. On Earth, a wide variety of silicate minerals occur in an even wider range of combinations as a result of the processes that have been forming and re-working the crust for billions of years. These processes include partial melting, crystallization, fractionation, metamorphism, weathering, and diagenesis. Living organisms also contribute to this geologic cycle. For example, a type of plankton known as diatoms construct their exoskeletons ("frustules") from silica extracted from seawater. The frustules of dead diatoms are a major constituent of deep ocean sediment, and of diatomaceous earth. General structure A silicate mineral is g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gemstones
A gemstone (also called a fine gem, jewel, precious stone, or semiprecious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks (such as lapis lazuli, opal, and obsidian) and occasionally organic materials that are not minerals (such as amber, jet, and pearl) are also used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other physical properties that have aesthetic value. Rarity and notoriety are other characteristics that lend value to gemstones. Apart from jewelry, from earliest antiquity engraved gems and hardstone carvings, such as cups, were major luxury art forms. A gem expert is a gemologist, a gem maker is called a lapidarist or gemcutter; a diamond cutter is called a diamantaire. Characteristics and classification The traditional classification in the West, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcium Minerals
Calcium is a chemical element with the Symbol (chemistry), symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust, and the third most abundant metal, after iron and aluminium. The most common calcium compound on Earth is calcium carbonate, found in limestone and the fossilised remnants of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium. The name derives from Latin language, Latin ''calx'' "lime (material), lime", which was obtained from heating limestone. Some calcium compounds were known to the ancients, though their chemistry was unknown until the seventeenth century. Pure calcium was isolated in 1808 via electrolysis of its oxide by Humphry Davy, who named the element. Calcium compounds are wid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1955 Introductions
Events January * January 3 – José Ramón Guizado becomes president of Panama. * January 17 – , the first nuclear-powered submarine, puts to sea for the first time, from Groton, Connecticut. * January 18– 20 – Battle of Yijiangshan Islands: The Chinese Communist People's Liberation Army seizes the islands from the Republic of China (Taiwan). * January 22 – In the United States, The Pentagon announces a plan to develop intercontinental ballistic missiles (ICBMs), armed with nuclear weapons. * January 23 – The Sutton Coldfield rail crash kills 17, near Birmingham, England. * January 25 – The Presidium of the Supreme Soviet of the Soviet Union announces the end of the war between the USSR and Germany, which began during World War II in 1941. * January 28 – The United States Congress authorizes President Dwight D. Eisenhower to use force to protect Formosa from the People's Republic of China. February * February 10 – The United States Seventh Fleet helps t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Ejecta
Ejecta (from the Latin: "things thrown out", singular ejectum) are particles ejected from an area. In volcanology, in particular, the term refers to particles including pyroclastic materials (tephra) that came out of a volcanic explosion and magma eruption volcanic vent, or crater, has traveled through the air or under water, and fell back on the ground surface or on the ocean floor. Volcanology Typically in volcanology, ejecta is a result of explosive eruptions. In an explosive eruption, large amounts of gas are dissolved in extremely viscous lava; this lava froths to the surface until the material is expelled rapidly due to the trapped pressure. Sometimes in such an event a lava plug or volcanic neck forms from lava that solidifies inside a volcano's vent, causing heat and pressure to build up to an extreme with no way to escape. When the blockage breaks and cannot sustain itself any longer, a more violent eruption occurs, which allows materials to be ejected out of the volcan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Italy
Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical region. Italy is also considered part of Western Europe, and shares land borders with France, Switzerland, Austria, Slovenia and the enclaved microstates of Vatican City and San Marino. It has a territorial exclave in Switzerland, Campione. Italy covers an area of , with a population of over 60 million. It is the third-most populous member state of the European Union, the sixth-most populous country in Europe, and the tenth-largest country in the continent by land area. Italy's capital and largest city is Rome. Italy was the native place of many civilizations such as the Italic peoples and the Etruscans, while due to its central geographic location in Southern Europe and the Mediterranean, the country has also historically b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
