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Geode Reference -22
A geode (; ) is a geological secondary formation within sedimentary and volcanic rocks. Geodes are hollow, vaguely spherical rocks, in which masses of mineral matter (which may include crystals) are secluded. The crystals are formed by the filling of vesicles in volcanic and subvolcanic rocks by minerals deposited from hydrothermal fluids; or by the dissolution of syngenetic concretions and partial filling by the same or other minerals precipitated from water, groundwater, or hydrothermal fluids. Formation Geodes can form in any cavity, but the term is usually reserved for more or less rounded formations in igneous and sedimentary rocks. They can form in gas bubbles in igneous rocks, such as vesicles in basaltic lava; or, as in the American Midwest, in rounded cavities in sedimentary formations. After rock around the cavity hardens, dissolved silicates and/or carbonates are deposited on the inside surface. Over time, this slow feed of mineral constituents from groundwater o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicate
A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used for any salt of such anions, such as sodium metasilicate; or any ester containing the corresponding chemical group, such as tetramethyl orthosilicate. The name "silicate" is sometimes extended to any anions containing silicon, even if they do not fit the general formula or contain other atoms besides oxygen; such as hexafluorosilicate . Most commonly, silicates are encountered as silicate minerals. For diverse manufacturing, technological, and artistic needs, silicates are versatile materials, both natural (such as granite, gravel, and garnet) and artificial (such as Portland cement, ceramics, glass, and waterglass). Structural principles In most silicates, a silicon atom occupies the center of an idealized tetrahedron whose cor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Illinois
Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. It borders on Lake Michigan to its northeast, the Mississippi River to its west, and the Wabash River, Wabash and Ohio River, Ohio rivers to its south. Of the fifty U.S. states, Illinois has the List of U.S. states and territories by GDP, fifth-largest gross domestic product (GDP), the List of U.S. states and territories by population, sixth-largest population, and the List of U.S. states and territories by area, 25th-most land area. Its capital city is Springfield, Illinois, Springfield in the center of the state, and the state's largest city is Chicago in the northeast. Present-day Illinois was inhabited by Indigenous peoples of the Americas#History, Indigenous cultures for thousands of years. The French were the first Europeans to arrive, settling near the Mississippi and Illinois River, Illinois rivers in the 17th century Illinois Country, as part of their sprawling colony of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Missouri
Missouri (''see #Etymology and pronunciation, pronunciation'') is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it borders Iowa to the north, Illinois, Kentucky and Tennessee to the east, Arkansas to the south and Oklahoma, Kansas, and Nebraska to the west. In the south are the Ozarks, a forested highland, providing timber, minerals, and recreation. At 1.5 billion years old, the St. Francois Mountains are among the oldest in the world. The Missouri River, after which the state is named, flows through the center and into the Mississippi River, which makes up the eastern border. With over six million residents, it is the List of U.S. states and territories by population, 19th-most populous state of the country. The largest urban areas are St. Louis, Kansas City, Missouri, Kansas City, Springfield, Missouri, Springfield, and Columbia, Missouri, Columbia. The Cap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iowa
Iowa ( ) is a U.S. state, state in the upper Midwestern United States, Midwestern region of the United States. It borders the Mississippi River to the east and the Missouri River and Big Sioux River to the west; Wisconsin to the northeast, Illinois to the east and southeast, Missouri to the south, Nebraska to the west, South Dakota to the northwest, and Minnesota to the north. Iowa is the List of U.S. states and territories by area, 26th largest in total area and the List of U.S. states and territories by population, 31st most populous of the List of states and territories of the United States, 50 U.S. states, with a population of 3.19 million. The state's List of capitals in the United States, capital, List of cities in Iowa, most populous city, and largest List of metropolitan statistical areas, metropolitan area fully located within the state is Des Moines, Iowa, Des Moines. A portion of the larger Omaha–Council Bluffs metropolitan area, Omaha, Nebraska, metropolitan area ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indiana
Indiana ( ) is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Lake Michigan to the northwest, Michigan to the north and northeast, Ohio to the east, the Ohio River and Kentucky to the south and southeast, and the Wabash River and Illinois to the west. Nicknamed "the Hoosier State", Indiana is the List of U.S. states and territories by area, 38th-largest by area and the List of U.S. states and territories by population, 17th-most populous of the List of states and territories of the United States, 50 states. Its capital and largest city is Indianapolis. Indiana was admitted to the Union as the 19th state on December 11, 1816. Indigenous peoples of the Americas, Indigenous resistance to American settlement was broken with defeat of the Tecumseh's confederacy in 1813. The new settlers were primarily Americans of British people, British ancestry from the East Coast of the United States, eastern seaboard and the Upland South ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraná And Etendeka Traps
The Paraná-Etendeka Large Igneous Province (PE-LIP) (or Paraná and Etendeka Plateau; or Paraná and Etendeka Province) is a large igneous province that includes both the main Paraná traps (in Paraná Basin, a South American geological basin) as well as the smaller severed portions of the flood basalts at the Etendeka traps (in northwest Namibia and southwest Angola). The original basalt flows occurred 136 to 132 million years ago. The province had a post-flow surface area of and an original volume projected to be in excess of 2.3 million km3. Geodynamics The basalt samples at Paraná and Etendeka have an age of about 132 Ma, during the Valanginian stage of the Early Cretaceous. Indirectly, the rifting and extension are probably the origin of the Paraná and Etendeka traps and it could be the origin of the Gough and Tristan da Cunha Islands as well, as they are connected by the Walvis Ridge (Gough/ Tristan hotspot). The seamounts of the Rio Grande Rise (25°S to 3 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amethyst
Amethyst is a Violet (color), violet variety of quartz. The name comes from the Koine Greek from - , "not" and (Ancient Greek) / (Modern Greek), "intoxicate", a reference to the belief that the stone protected its owner from Alcohol intoxication, drunkenness. Ancient Greece, Ancient Greeks wore amethyst and carved drinking vessels from it in the belief that it would prevent intoxication. Amethyst, a Gemstone, semiprecious stone, is often used in jewelry. Structure Amethyst is a violet variety of quartz () and owes its violet color to Gemstone irradiation, irradiation, impurities of iron () and in some cases other transition metals, and the presence of other trace elements, which result in complex crystal lattice substitutions. The irradiation causes the iron ions that replace silicon, Si in the lattice to lose an electron and form a color center. Amethyst is a three-dimensional network of tetrahedra where the silicon atoms are in the center and are surrounded by fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mexico
Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundary, maritime boundaries with the Pacific Ocean to the west, the Caribbean Sea to the southeast, and the Gulf of Mexico to the east. Mexico covers 1,972,550 km2 (761,610 sq mi), and is the List of countries by area, thirteenth-largest country in the world by land area. With a population exceeding 130 million, Mexico is the List of countries by population, tenth-most populous country in the world and is home to the Hispanophone#Countries, largest number of native Spanish speakers. Mexico City is the capital and List of cities in Mexico, largest city, which ranks among the List of cities by population, most populous metropolitan areas in the world. Human presence in Mexico dates back to at least 8,000 BC. Mesoamerica, considered a cradle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Namibia
Namibia, officially the Republic of Namibia, is a country on the west coast of Southern Africa. Its borders include the Atlantic Ocean to the west, Angola and Zambia to the north, Botswana to the east and South Africa to the south; in the northeast, approximating a quadripoint, Zimbabwe lies less than 200 metres (660 feet) away along the Zambezi, Zambezi River near Kazungula, Zambia. Namibia's capital and largest city is Windhoek. Namibia is the driest country in sub-Saharan Africa, and has been inhabited since prehistoric times by the Khoekhoe, Khoi, San people, San, Damara people, Damara and Nama people. Around the 14th century, immigration, immigrating Bantu peoples arrived as part of the Bantu expansion. From 1600 the Ovambo people#History, Ovambo formed kingdoms, such as Ondonga and Oukwanyama. In 1884, the German Empire established rule over most of the territory, forming a colony known as German South West Africa. Between 1904 and 1908, German troops waged a punitive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uruguay
Uruguay, officially the Oriental Republic of Uruguay, is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast, while bordering the Río de la Plata to the south and the Atlantic Ocean to the southeast. It is part of the Southern Cone region of South America. Uruguay covers an area of approximately . It has a population of almost 3.5 million people, of whom nearly 2 million live in Montevideo metropolitan area, the metropolitan area of its capital and List of cities in Uruguay, largest city, Montevideo. The area that became Uruguay was first inhabited by groups of hunter gatherer, hunter gatherers 13,000 years ago. The first European explorer to reach the region was Juan Díaz de Solís in 1516, but the area was colonized later than its neighbors. At the time of Spanish colonization of the Americas, European arrival, the Charrúa were the predominant tribe, alongside other groups such as the Guaraní people ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brazil
Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population, seventh-largest by population, with over 212 million people. The country is a federation composed of 26 Federative units of Brazil, states and a Federal District (Brazil), Federal District, which hosts the capital, Brasília. List of cities in Brazil by population, Its most populous city is São Paulo, followed by Rio de Janeiro. Brazil has the most Portuguese-speaking countries, Portuguese speakers in the world and is the only country in the Americas where Portuguese language, Portuguese is an Portuguese-speaking world, official language. Bounded by the Atlantic Ocean on the east, Brazil has a Coastline of Brazil, coastline of . Covering roughly half of South America's land area, it Borders of Brazil, borders all other countries and ter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
