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Kornerupine
Kornerupine (also called ''Prismatine'') is a rare boro-silicate mineral with the chemical formula . It crystallizes in the orthorhombic - dipyramidal crystal system as brown, green, yellow to colorless slender tourmaline like prisms or in massive fibrous forms. It has a Mohs hardness of 7 and a specific gravity of 3.3 to 3.34. Its indices of refraction are nα=1.660 - 1.671, nβ=1.673 - 1.683 and nγ=1.674 - 1.684. It occurs in boron-rich volcanic and sedimentary rocks which have undergone high grade metamorphism. It is also found in metamorphosed anorthosite complexes. Kornerupine is valued as a gemstone when it is found in translucent green to yellow shades. The emerald green varieties are especially sought after. It forms a solid solution series with prismatine. Strongly pleochroic, it appears green or reddish brown when viewed from different directions. It has a vitreous luster. It was first described in 1884 for an occurrence in Fiskernæs in southwest Greenland. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pleochroism
Pleochroism (from Greek πλέων, ''pléōn'', "more" and χρῶμα, ''khrôma'', "color") is an optical phenomenon in which a substance has different colors when observed at different angles, especially with polarized light. Background Anisotropic crystals will have optical properties that vary with the direction of light. The direction of the electric field determines the polarization of light, and crystals will respond in different ways if this angle is changed. These kinds of crystals have one or two optical axes. If absorption of light varies with the angle relative to the optical axis in a crystal then pleochroism results. Anisotropic crystals have double refraction of light where light of different polarizations is bent different amounts by the crystal, and therefore follows different paths through the crystal. The components of a divided light beam follow different paths within the mineral and travel at different speeds. When the mineral is observed at some a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fiskernaes
Qeqertarsuatsiaat, formerly Fiskenæsset or Fiskernæs, is a settlement in the Sermersooq municipality in southwestern Greenland, located on an island off the shores of Labrador Sea. Its population was 169 in 2020. History Kikertarsocitsiak or Qeqertarsuatsiaat has long been the local name for the island (Kalaallisut: "Rather Large Islands"). It was first settled by the Danes as Fiskernæs in 1754. The name was often anglicized as Fisher's Inlet. The trading post was founded by the merchant Anders Olsen on behalf of the Danish General Trade Company, which was granted a royal monopoly on trade in Greenland but only in and around its settlements. Like most Greenlandic trading posts, it was a location for the Danes to trade imported goods for seal skins and seal and whale blubber gathered by Kalaallit in the area. Unusually, the settlement became the early center of Greenland's salmon and cod fisheries and it was as common to see the large "woman's boat" or umiak as the smaller ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthorhombic Minerals
In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with a rectangular base (''a'' by ''b'') and height (''c''), such that ''a'', ''b'', and ''c'' are distinct. All three bases intersect at 90° angles, so the three lattice vectors remain mutually orthogonal. Bravais lattices There are four orthorhombic Bravais lattices: primitive orthorhombic, base-centered orthorhombic, body-centered orthorhombic, and face-centered orthorhombic. For the base-centered orthorhombic lattice, the primitive cell has the shape of a right rhombic prism;See , row oC, column Primitive, where the cell parameters are given as a1 = a2, α = β = 90° it can be constructed because the two-dimensional centered rectangular base layer can also be described with primitive rhombic axes. Note that the length a of the primiti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sorosilicates
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 general ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Africa
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countries of Namibia, Botswana, and Zimbabwe; and to the east and northeast by Mozambique and Eswatini. It also completely enclaves the country Lesotho. It is the southernmost country on the mainland of the Old World, and the second-most populous country located entirely south of the equator, after Tanzania. South Africa is a biodiversity hotspot, with unique biomes, plant and animal life. With over 60 million people, the country is the world's 24th-most populous nation and covers an area of . South Africa has three capital cities, with the executive, judicial and legislative branches of government based in Pretoria, Bloemfontein, and Cape Town respectively. The largest city is Johannesburg. About 80% of the population are Black South Afri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tanzania
Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands and the Indian Ocean to the east; Mozambique and Malawi to the south; Zambia to the southwest; and Rwanda, Burundi, and the Democratic Republic of the Congo to the west. Mount Kilimanjaro, Africa's highest mountain, is in northeastern Tanzania. According to the United Nations, Tanzania has a population of million, making it the most populous country located entirely south of the equator. Many important hominid fossils have been found in Tanzania, such as 6-million-year-old Pliocene hominid fossils. The genus Australopithecus ranged across Africa between 4 and 2 million years ago, and the oldest remains of the genus ''Homo'' are found near Lake Olduvai. Following the rise of '' Homo erectus'' 1.8 million years ago, humanity spread ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sri Lanka
Sri Lanka (, ; si, ශ්රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, and southeast of the Arabian Sea; it is separated from the Indian subcontinent by the Gulf of Mannar and the Palk Strait. Sri Lanka shares a maritime border with India and Maldives. Sri Jayawardenepura Kotte is its legislative capital, and Colombo is its largest city and financial centre. Sri Lanka has a population of around 22 million (2020) and is a multinational state, home to diverse cultures, languages, and ethnicities. The Sinhalese are the majority of the nation's population. The Tamils, who are a large minority group, have also played an influential role in the island's history. Other long established groups include the Moors, the Burghers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Madagascar
Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa across the Mozambique Channel. At Madagascar is the world's List of island countries, second-largest island country, after Indonesia. The nation is home to around 30 million inhabitants and consists of the island of Geography of Madagascar, Madagascar (the List of islands by area, fourth-largest island in the world), along with numerous smaller peripheral islands. Following the prehistoric breakup of the supercontinent Gondwana, Madagascar split from the Indian subcontinent around 90 million years ago, allowing native plants and animals to evolve in relative isolation. Consequently, Madagascar is a biodiversity hotspot; over 90% of wildlife of Madagascar, its wildlife is endemic. Human settlement of Madagascar occurred during or befo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kenya
) , national_anthem = "Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , official_languages = Constitution (2009) Art. 7 ational, official and other languages"(1) The national language of the Republic is Swahili. (2) The official languages of the Republic are Swahili and English. (3) The State shall–-–- (a) promote and protect the diversity of language of the people of Kenya; and (b) promote the development and use of indigenous languages, Kenyan Sign language, Braille and other communication formats and technologies accessible to persons with disabilities." , languages_type = National language , languages = Swahili , ethnic_groups = , ethnic_groups_year = 2019 census , religion = , religion_year = 2019 census , demonym = ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quebec
Quebec ( ; )According to the Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is one of the thirteen provinces and territories of Canada. It is the largest province by area and the second-largest by population. Much of the population lives in urban areas along the St. Lawrence River, between the most populous city, Montreal, and the provincial capital, Quebec City. Quebec is the home of the Québécois nation. Located in Central Canada, the province shares land borders with Ontario to the west, Newfoundland and Labrador to the northeast, New Brunswick to the southeast, and a coastal border with Nunavut; in the south it borders Maine, New Hampshire, Vermont, and New York in the United States. Between 1534 and 1763, Quebec was called ''Canada'' and was the most developed colony in New France. Following the Seven Years' War, Quebec b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by total area. Its southern and western border with the United States, stretching , is the world's longest binational land border. Canada's capital is Ottawa, and its three largest metropolitan areas are Toronto, Montreal, and Vancouver. Indigenous peoples have continuously inhabited what is now Canada for thousands of years. Beginning in the 16th century, British and French expeditions explored and later settled along the Atlantic coast. As a consequence of various armed conflicts, France ceded nearly all of its colonies in North America in 1763. In 1867, with the union of three British North American colonies through Confederation, Canada was formed as a federal dominion of four provinces. This began an accretion of provinces an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myanmar
Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John C. Wells, John Wells explains, the English spellings of both Myanmar and Burma assume a non-rhotic variety of English, in which the letter r before a consonant or finally serves merely to indicate a long vowel: [ˈmjænmɑː, ˈbɜːmə]. So the pronunciation of the last syllable of Myanmar as [mɑːr] or of Burma as [bɜːrmə] by some speakers in the UK and most speakers in North America is in fact a spelling pronunciation based on a misunderstanding of non-rhotic spelling conventions. The final ''r'' in ''Myanmar'' was not intended for pronunciation and is there to ensure that the final a is pronounced with the broad a, broad ''ah'' () in "father". If the Burmese name my, မြန်မာ, label=none were spelled "Myanma" in English, this would b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
