A mineral is a substance normally inorganic, organic, more rarely, formed naturally or artificially synthesized, defined by its chemical composition and arrangement of its atoms with a frequency and a specific symmetry reflected in the space group and the system crystalline minerals. Minerals are generally solid in normal conditions of temperature and pressure (STP) and combine to form the rocks forming the crust and, more generally, the lithosphere. A mineral is characterized by its physicochemical properties, toughness ranked on the Mohs scale of 1 to 10 (knowing that 10 is the hardest and 1 the least hard) and its chemical formula, it can vary (see . mineralogy). In each type of site, more atoms can be replaced, giving rise to isomorphic substitutions. This is the case, for example, iron and magnesium in olivine or sodium and calcium plagioclase. The composition of a mineral is so often between the extremes more or less distant, while intermediate compound belonging to the series. For example, while mica whose composition is between that of phlogopite and annite is that of biotite. Changes in the composition are accepted as readily mineralogist considers minerals as mineral species, although characterized by its physical properties - the most "visible" is its symmetry, color, hardness, luster, track and the index of refraction - and chemicals, but can not be confused with the elements or compounds of the chemist. There are over 4,000 known minerals, which are mainly classified according to chemical and crystallographic criteria. Their chemical composition can be grouped into ten main classes (classification of Strunz 9th edition, 2001). native elements, consisting of a single element more or less pure, such as carbon (with diamond), sulfur, gold, copper, platinum. Copyright Text is available under Creative Commons Attribution Share-Alike, other conditions may apply. See Terms of Use for more details and credits graphics. If reused texts of this page, see how to cite authors and include the license. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc.., Charitable organization governed by section 501 (c) (3) tax United States.
A study involving French and American scientists demonstrate the presence of hydrated minerals in the lower layers of some craters in the northern hemisphere of Mars. A discovery that supports the thesis of a wet past for our neighboring red planet. In recent years, spectrometers space probes Mars Reconnaissance Orbiter (NASA) and Mars Express (ESA) have uncovered several regions rich in phyllosilicates or hydrated minerals on the surface of Mars. So far, these deposits showing a contact of rocks with liquid water were observed exclusively in the southern hemisphere. Virtually nothing had been previously detected in soil and subsoil of the northern hemisphere ... Probably because of the thick layer of volcanic lava that covers a very large extent. However, French and American researchers have scrutinized the images obtained with the MRO and Mars Express orbiters over 900 craters. For now, they spotted traces of hydrous minerals in 9 of them. The impact craters are ideal targets for this type of research. Asteroids and meteorites are the source, break the crust of volcanic rock formed over 4 billion years, touching the ground ... So, are proven to lower layers and sediment previously hidden and ignored and space probes Observing that fly. Spring storm at the north pole of Mars Mars opposition (see Mars at Opposition January 29, 2010) is a great event for all amateur astronomers .. Avalanches on Mars photographed by the MRO NASA's Mars Reconnaissance Orbiter (MRO) was again photographed spring avalanches in the surface of Mars. De. Wonderful videos of the surface of Mars by Doug Ellison Scenic videos from two regions of Mars Crater Mojave and Athabasca Valles. From the data acquired by .. Sirenum Fossae photographed by Mars Express This snapshot produced by the European spacecraft Mars Express and the stereo camera high-resolution (High Resolution Stereo Camera, .. sup VNUS is great to have possdde amount of water in the pass-107 views.
I discovered St. Ambroix with pleasure. Medieval city nestled in a bend of the Ceze, rich and proud history. The past is written but the present and the future belongs to us. We build, day after day, which is a continuation of this story. Sometimes actor, sometimes the reader, often both at once, and we'll live together, the pages of this blog by writing the following history of the city of Volos Biou (cattle stealing). Expected each summer and true to its reputation, this event will go this year beyond its promises, because almost completely new .... The gems are still there and fine, with explanations and demonstrations of various sizes. The beautiful minerals from Brazil, so gaudy and colorful, yet never the same as those of Madagascar and Malagasy fossil will be there too. Finds world, from the latest research, once again this delight visitors and connoisseurs. ... A novelty! Asia will be present with minerals exceptional Himalayas: aquamarine, tourmaline, topaz and so on. "These are pieces of great beauty" ad Pierrette Durand. Africa will be highlighted as this year, with the addition of Morocco always well represented, Mauritania and rare stromatolites. These formations are spectacular, and Biochemical aged between 1 and 2 billion years! All explanations on these courses that are being built today will be given in the stands .... A further innovation this year: a space for teaching. for everyone, children and adults who want to learn more about the "manufacture" of rocks, mountain building and plains, the crystallization of minerals. With always a place for exchange and discussion, loupes to observe micro minerals, stones trimmers to burst and release the crystals, a raffle, an area appetite suppressant and thirst cut. Minerals and Fossils Club Cévenol welcome you to the Maison des Associations 10 and July 11 09h-19h non-stop.

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