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Lake Superior Agate
The Lake Superior agate is a type of agate stained by iron and found on the shores of Lake Superior. Its wide distribution and iron-rich bands of color reflect the gemstone's geologic history in Minnesota, Wisconsin, Nebraska, Iowa, Kansas, and Michigan. In 1969 the Lake Superior agate was designated by the Minnesota Legislature as the official state gemstone. The Lake Superior agate was selected because the agate reflects many aspects of Minnesota. It was formed during lava eruptions that occurred in Minnesota about a billion years ago. The stone's predominant red color comes from iron, a major Minnesota industrial mineral found extensively throughout the Iron Range region. Finally, the Lake Superior agate can be found in many regions of Minnesota as it was distributed by Wisconsin glaciation, glacial movement across Minnesota 10,000 to 15,000 years ago. Geologic history More than a billion years ago, the North American continent began to split apart along Plate tectonics, pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gemstone
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, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of Michigan
Michigan consists of two peninsulas surrounded primarily by four of the Great Lakes and a variety of nearby islands. The Upper Peninsula is bounded on the southwest by Wisconsin, and the Lower Peninsula is bounded on the south by Indiana and Ohio. Both land masses are also separated from the Canadian province of Ontario by waterways of the Great Lakes, and from each other by the Straits of Mackinac. Because its land is largely surrounded by the Great Lakes, which flow into the Saint Lawrence River, Michigan is the only U.S. state whose streams and rivers are almost entirely within the Great Lakes-St. Lawrence watershed. Michigan's territorial waters include roughly half each of Lake Superior, Lake Michigan, and Lake Huron, and smaller areas of Lake St. Clair and Lake Erie. It includes an estimated 11,000 inland lakes. It encompasses of land, of Great Lakes waters, and of inland waters. Its territorial waters are second in area only to those of Alaska. At a total area of – i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of Iowa
The geography of Iowa includes the study of bedrock, landforms, rivers, geology, paleontology and urbanisation of the U.S. state of Iowa. The state covers an area of 56,272.81 sq mi (145,746 km2). Bedrock features Iowa's bedrock geology generally increases in age from west to east. In northwest Iowa Cretaceous bedrock is ca. 74 million years old, in eastern Iowa Cambrian bedrock dates to ca. 500 million years ago. Meteor impact structures Manson impact structure Seventy-four million years ago, a large asteroid crashed into what is now southeast Pocahontas county creating the Manson crater. Nearly 22 miles in diameter, it would have killed most animals within 650 miles, roughly an area from modern Denver to Detroit. This was originally thought to have been one of the causes of the dinosaur extinction, but recalculation of the impact's age indicates it occurred some 12 million years before the mass extinction. Although glaciation has erased all surface evidence of the impa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of Wisconsin
The geology of Wisconsin includes Precambrian crystalline basement rock over three billion years old. A widespread marine environment during the Paleozoic flooded the region, depositing sedimentary rocks which cover most of the center and south of the state. Geologic history, stratigraphy and tectonics The oldest Precambrian rocks in Wisconsin are late Archean quartzofeldspathic gneiss, migmatite and amphibolite up to three billion years old and igneous rock such as the granite of the Puritan Quartz Monzonite. Mafic and intermediate metavolcanic rocks together with metasedimentary rocks are found in the Ramsey Formation in Iron County and iron formations in Jackson County. The metasediments and metavolcanics formed first, followed by granites more than 2.7 billion years ago. The rock record contains an uncertain age gap with younger 1.8 billion years old Proterozoic quartzofeldspathic and migmatite gneiss, with amphibolite and biotite schist. Around 1.9 billion years ago, mafic, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of Minnesota
The geology of Minnesota comprises the rock, minerals, and soils of the U.S. state of Minnesota, including their formation, development, distribution, and condition. The state's geologic history can be divided into three periods. The first period was a lengthy period of geologic instability from the origin of the planet until roughly 1,100 million years ago. During this time, the state's Precambrian bedrock was formed by volcanism and the deposition of sedimentary rock and then modified by processes such as faulting, folding and erosion. In the second period, many layers of sedimentary rock were formed by deposition and lithification of successive layers of sediment from runoff and repeated incursions of the sea. In the third and most recent period starting about 1.8 million years ago, glaciation eroded previous rock formations and deposited deep layers of glacial till over most of the state, and created the beds and valleys of modern lakes and rivers. Minnesota's geologic r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symbols Of Minnesota
A symbol is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise very different concepts and experiences. All communication (and data processing) is achieved through the use of symbols. Symbols take the form of words, sounds, gestures, ideas, or visual images and are used to convey other ideas and beliefs. For example, a red octagon is a common symbol for "STOP"; on maps, blue lines often represent rivers; and a red rose often symbolizes love and compassion. Numerals are symbols for numbers; letters of an alphabet may be symbols for certain phonemes; and personal names are symbols representing individuals. The variable 'x', in a mathematical equation, may symbolize the position of a particle in space. The academic study of symbols is semiotics. In cartography, an organized collection of symbols forms a legend for a map. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agates
Agate () is a common rock formation, consisting of chalcedony and quartz as its primary components, with a wide variety of colors. Agates are primarily formed within Volcanic rock, volcanic and metamorphic rocks. The ornamental use of agate was common in Ancient Greece, in assorted jewelry and in the seal stones of Greek warriors, while bead necklaces with pierced and polished agate date back to the 3rd millennium BCE in the Indus Valley civilisation. Etymology The stone was given its name by Theophrastus, a Greeks, Greek philosopher and naturalist, who discovered the stone along the shore line of the Dirillo, Dirillo River or Achates ( grc, Ἀχάτης) in Sicily, sometime between the 4th and 3rd centuries BCE. Formation and properties Agate minerals have the tendency to form on or within pre-existing rocks, creating difficulties in accurately determining their time of formation. Their host rocks have been dated to have formed as early as the Archean Eon. Agates are most c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northwestern Ontario
Northwestern Ontario is a secondary region of Northern Ontario in the Canadian province of Ontario which lies north and west of Lake Superior and west of Hudson Bay and James Bay. It includes most of subarctic Ontario. Its western boundary is the Canadian province of Manitoba, which disputed Ontario's claim to the western part of the region. Ontario's right to Northwestern Ontario was determined by the Judicial Committee of the Privy Council in 1884ONTARIO-MANITOBA BOUNDARY CASE and confirmed by the Canada (Ontario Boundary) Act, 1889, of the Parliament of the United Kingdom. In 1912, the Parliament of Canada by the ''Ontario Boundaries Extension Act'' gave jurisdiction over the District of Patricia to Ontario, thereby extending the northern boundary of the province to Hudson Bay. For some purposes, Northwestern Ontario and Northeastern Ontario are treated as separate regions, while for other purposes they are grouped together as Northern Ontario. Geographic subdivisions Northwe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thunder Bay
Thunder Bay is a city in and the seat of Thunder Bay District, Ontario, Canada. It is the most populous municipality in Northwestern Ontario and the second most populous (after Greater Sudbury) municipality in Northern Ontario; its population is 108,843 according to the 2021 Canadian Census. Located on Lake Superior, the census metropolitan area of Thunder Bay has a population of 123,258 and consists of the city of Thunder Bay, the municipalities of Oliver Paipoonge and Neebing, the townships of Shuniah, Conmee, O'Connor, and Gillies, and the Fort William First Nation. European settlement in the region began in the late 17th century with a French fur trading outpost on the banks of the Kaministiquia River.Brief History of Thunder Bay City of Thunder Bay. Retrieved ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, nine Minor Outlying Islands, and 326 Indian reservations. The United States is also in free association with three Pacific Island sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Republic of Palau. It is the world's third-largest country by both land and total area. It shares land borders with Canada to its north and with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 million, it is the most populous country in the Americas and the third most populous in the world. The national capital of the United States is Washington, D.C. and its most populous city and principal financial center is New York City. Paleo-Americ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cabochon
A cabochon (; ) is a gemstone that has been shaped and polished, as opposed to faceted. The resulting form is usually a convex (rounded) obverse with a flat reverse. Cabochon was the default method of preparing gemstones before gemstone cutting developed. Application Cutting ''en cabochon'' (French: "in the manner of a cabochon") is usually applied to opaque gems, while faceting is usually used for transparent stones. Hardness is also taken into account as softer gemstones with a hardness lower than 7 on the Mohs hardness scale are easily scratched, mainly by silicon dioxide in dust and grit. This would quickly make translucent gems unattractive—instead they are polished as cabochons, making the scratches less evident. In asteriated stones such as star sapphires and chatoyant stones such as cat's eye chrysoberyl, a domed cabochon cut can show the star or eye, which would not be visible in a faceted cut. The usual shape for cutting cabochons is an ellipse, because the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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