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Orbicular Jasper
Orbicular jasper is a variety of jasper which contains variably-colored ''orbs'' or spherical inclusions or zones. In highly silicified rhyolite or tuff, quartz and feldspar crystallize in radial aggregates of needle-like crystals which provide the basis or ''seed'' for the orbicular structure seen in this kind of jasper. The material is quite attractive when polished and is used as an ornamental stone or gemstone. Various local or commercial names have been used for the material, such as kinradite, oregonite, ocean jasper and poppy-patterned jasper, depending on the source. ''Poppy-patterned jasper'' or ''poppy jasper'' is the varietal name for material from several locations, but the most well known is from Morgan Hill, Santa Clara County, California. The trade name Ocean Jasper is used for a variety found along the intertidal shores of northeast Madagascar. In Nebraska orbicular jasper is found in altered rhyolite beds noted for a variety of jaspers and related agate Aga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jasper
Jasper, an aggregate of microgranular quartz and/or cryptocrystalline chalcedony and other mineral phases, is an opaque, impure variety of silica, usually red, yellow, brown or green in color; and rarely blue. The common red color is due to iron(III) inclusions. Jasper breaks with a smooth surface and is used for ornamentation or as a gemstone. It can be highly polished and is used for items such as vases, seals, and snuff boxes. The density of jasper is typically 2.5 to 2.9 g/cm3. Jaspillite is a banded-iron-formation rock that often has distinctive bands of jasper. Etymology and history The name means "spotted or speckled stone," and is derived via Old French (variant of Anglo-Norman ''jaspe'') and Afroasiatic language (cf. Hebrew language">Hebrew ' , Akkadian ''yashupu''). This Semitic etymology is believed to be unrelated to that of the English given name Persian origin, though the Persian word for the mineral jasper is also ''yashum'' ( :fa:یشم">ی� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhyolite
Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture (geology), texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained matrix (geology), groundmass. The mineral assemblage is predominantly quartz, sanidine, and plagioclase. It is the extrusive equivalent of granite. Its high silica content makes rhyolitic magma extremely viscosity, viscous. This favors explosive eruptions over effusive eruptions, so this type of magma is more often erupted as pyroclastic rock than as lava flows. Rhyolitic ash-flow tuffs are among the most voluminous of continental igneous rock formations. Rhyolitic tuff has been used extensively for construction. Obsidian, which is rhyolitic volcanic glass, has been used for tools from prehistoric times to the present day because it can be shaped to an extremely sharp edge. Rhyolitic pumice finds use as an abrasive, in concrete, and as a soil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuff
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock containing 25% to 75% ash is described as ''tuffaceous'' (for example, ''tuffaceous sandstone''). A pyroclastic rock containing 25–75% volcanic bombs or volcanic blocks is called tuff breccia. Tuff composed of sandy volcanic material can be referred to as volcanic sandstone. Tuff is a relatively soft rock, so it has been used for construction since ancient times. Because it is common in Italy, the Romans used it often for construction. The Rapa Nui people used it to make most of the ''moai'' statues on Easter Island. Tuff can be classified as either igneous or sedimentary rock. It is usually studied in the context of igneous petrology, although it is sometimes described using sedimentological terms. Tuff is often erroneously called t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of Silicon dioxide, SiO2. Quartz is, therefore, classified structurally as a Silicate mineral#Tectosilicates, framework silicate mineral and compositionally as an oxide mineral. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar. Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral. The transformation from α-quartz to β-quartz takes place abruptly at . Since the transformation is accompanied by a significant change in volume, it can easily induce microfracturing of ceramics or rocks passing through this temperature threshold. There are many different varieties of quartz, several of which are classifi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Feldspar
Feldspar ( ; sometimes spelled felspar) is a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feldspars and the ''alkali'' (potassium-sodium) feldspars. Feldspars make up about 60% of the Earth's crust and 41% of the Earth's continental crust by weight. Feldspars crystallize from magma as both intrusive and extrusive igneous rocks and are also present in many types of metamorphic rock. Rock formed almost entirely of calcic plagioclase feldspar is known as anorthosite. Feldspars are also found in many types of sedimentary rocks. Etymology The name ''feldspar'' derives from the German , a compound of the words ' ("field") and ("flake"). had long been used as the word for "a rock easily cleaved into flakes"; was introduced in the 18th century as a more specific term, referring perhaps to its comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aggregate (geology)
In the Earth sciences, aggregate has three possible meanings. In mineralogy Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical mineralogy, optical) properties of minerals and mineralized artifact (archaeology), artifacts. Specific s ... and petrology, an aggregate is a mass of mineral crystals, mineraloid particles or Rock (geology), rock particles. Examples are Dolomite (rock), dolomite, which is an aggregate of crystals of the mineral dolomite (mineral), dolomite, and ''rock gypsum'', an aggregate of crystals of the mineral gypsum. Lapis lazuli is a type of rock composed of an aggregate of crystals of many minerals including lazurite, pyrite, phlogopite, calcite, potassium feldspar, wollastonite and some sodalite group minerals. In the construction industry, an aggregate (often referred to as a construction aggregate) is sand, gravel or crushed rock that has been mining, mined or Q ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gemstone
A gemstone (also called a fine gem, jewel, precious stone, semiprecious stone, or simply gem) is a piece of mineral crystal which, when cut or polished, is used to make jewellery, jewelry or other adornments. Certain Rock (geology), rocks (such as lapis lazuli, opal, and obsidian) and occasionally organic chemistry, organic materials that are not minerals (such as amber, Jet (gemstone), jet, and pearl) may also be used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some softer minerals such as brazilianite may be used in jewelry because of their color or Lustre (mineralogy), luster or other physical properties that have aesthetic value. However, generally speaking, soft minerals are not typically used as gemstones by virtue of their brittleness and lack of durability. Found all over the world, the industry of coloured gemstones (i.e. anything other than diamonds) is currently estimated at US$1.55billion and is projected to s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morgan Hill, California
Morgan Hill is a city in Santa Clara County, California, at the southern tip of Silicon Valley in the San Francisco Bay Area. Morgan Hill is an affluent residential community, the seat of several high-tech companies, and a dining and recreational destination, owing to its luxury hospitality, wineries, and nature parks. History Prior to the arrival of Spanish colonists, Santa Clara Valley had been inhabited by the Tamien nation of Ohlone people for more than 6,000 years. In that area, the Matalan tribe lived in a hunter-gatherer society. Before the area was colonized as part of the Alta California province of the Viceroyalty of New Spain, the 1772 Spanish expedition led by Pedro Fages and Father Juan Crespí, the two explorers camped in the area around Morgan Hill alongside Llagas Creek. The location of their camp subsequently became a campsite for Spanish soldiers on their way from New Spain to Alta California. With the founding of Mission Santa Clara de Asís in 1777, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Santa Clara County, California
Santa Clara County, officially the County of Santa Clara, is the sixth-most populous county in the U.S. state of California, with a population of 1,936,259 as of the 2020 United States census, 2020 census. Santa Clara County and neighboring San Benito County, California, San Benito County form the San Jose–Sunnyvale–Santa Clara metropolitan statistical area, which is part of the larger San Jose–San Francisco–Oakland combined statistical area. Santa Clara is the most populous county in the San Francisco Bay Area and in Northern California. The county seat and largest city with a population of 971,233 is San Jose, California, San Jose, the List of United States cities by population, 13th-most populous city in the nation, List of cities and towns in California, California's third-most populous city, and the List of cities and towns in the San Francisco Bay Area, most populous city in Northern California. Home to Silicon Valley, Santa Clara County is an economic center for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Madagascar
Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, fourth largest island, the List of island countries, second-largest island country, and the List of countries and dependencies by area, 46th largest country overall. Its capital and List of cities in Madagascar, largest city is Antananarivo. Following the prehistoric breakup of the supercontinent Gondwana, Madagascar split from Africa during the Early Jurassic period, around 180 million years ago, and separated from the Indian subcontinent approximately 90 million years ago. This isolation allowed native plants and animals to evolve in relative seclusion; as a result, Madagascar is a biodiversity hotspot and one of the world's 17 megadiverse countries, with over 90% of its wildlife of Madagascar, wildlife being endemic. The island has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nebraska
Nebraska ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the southwest; and Wyoming to the west. Nebraska is the List of U.S. states and territories by area, 16th-largest state by land area, with just over . With a population of over 2 million as of 2024, it is the List of U.S. states and territories by population, 38th-most populous state and the List of states and territories of the United States by population density, eighth-least densely populated. Its List of capitals in the United States, capital is Lincoln, Nebraska, Lincoln, and its List of municipalities in Nebraska, most populous city is Omaha, Nebraska, Omaha, which is on the Missouri River. Nebraska was admitted into the United States in 1867, two years after the end of the American Civil War. The Nebras ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
