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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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pleochroism
Pleochroism is an optical phenomenon in which a substance has different colors when observed at different angles, especially with Polarization (waves), polarized light. Etymology The roots of the word are from Greek (). It was first made compound in the German term ''Pleochroismus'' by mineralogist Wilhelm Haidinger in 1854, in the journal ''Annalen der Physik und Chemie''. Its first known English usage is by geologist James Dana in 1854. Background Anisotropy, 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 Polarization (waves), polarizations is bent di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicate Minerals
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, the crystalline forms of silica (silicon dioxide, ) are usually considered to be tectosilicates, and they are classified as such in the Dana system (75.1). However, the Nickel-Strunz system classifies them as oxide minerals (4.DA). 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 s ... [...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 prim ... [...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, the crystalline forms of silica (silicon dioxide, ) are usually considered to be tectosilicates, and they are classified as such in the Dana system (75.1). However, the Nickel-Strunz system classifies them as oxide minerals (4.DA). 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 seawat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Africa
South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic Ocean, South Atlantic and Indian Ocean; to the north by the neighbouring countries of Namibia, Botswana, and Zimbabwe; to the east and northeast by Mozambique and Eswatini; and it encloses Lesotho. Covering an area of , the country has Demographics of South Africa, a population of over 64 million people. Pretoria is the administrative capital, while Cape Town, as the seat of Parliament of South Africa, Parliament, is the legislative capital, and Bloemfontein is regarded as the judicial capital. The largest, most populous city is Johannesburg, followed by Cape Town and Durban. Cradle of Humankind, Archaeological findings suggest that various hominid species existed in South Africa about 2.5 million years ago, and modern humans inhabited the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tanzania
Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; 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. According to a 2024 estimate, Tanzania has a population of around 67.5 million, making it the most populous country located entirely south of the equator. Many important hominid fossils have been found in Tanzania. In the Stone and Bronze Age, prehistoric migrations into Tanzania included South Cushitic languages, Southern Cushitic speakers similar to modern day Iraqw people who moved south from present-day Ethiopia; Eastern Cushitic people who moved into Tanzania from north of Lake Turkana about 2,000 and 4,000 years ago; and the Southern Nilotic languages, Southern Nilotes, including the Datooga people, Datoog, who originated fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, also known historically as Ceylon, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, separated from the Indian subcontinent, Indian peninsula by the Gulf of Mannar and the Palk Strait. It shares a maritime border with the Maldives in the southwest and India in the northwest. Sri Jayawardenepura Kotte is the legislative capital of Sri Lanka, while the largest city, Colombo, is the administrative and judicial capital which is the nation's political, financial and cultural centre. Kandy is the second-largest urban area and also the capital of the last native kingdom of Sri Lanka. The most spoken language Sinhala language, Sinhala, is spoken by the majority of the population (approximately 17 million). Tamil language, Tamil is also spoken by approximately five million people, making it the second most-spoken language in Sri Lanka. Sri Lanka has a population of appr ... [...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] |
Kenya
Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. Kenya's capital and largest city is Nairobi. Its second-largest and oldest city is Mombasa, a major port city located on Mombasa Island. Other major cities within the country include Kisumu, Nakuru & Eldoret. Going clockwise, Kenya is bordered by South Sudan to the northwest (though much of that border includes the disputed Ilemi Triangle), Ethiopia to the north, Somalia to the east, the Indian Ocean to the southeast, Tanzania to the southwest, and Lake Victoria and Uganda to the west. Kenya's geography, climate and population vary widely. In western, rift valley counties, the landscape includes cold, snow-capped mountaintops (such as Batian, Nelion and Point Lenana on Mount Kenya) with vast surrounding forests, wildlife and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quebec
Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, New Brunswick to the southeast and a coastal border with the territory of Nunavut. In the south, it shares a border with the United States. Between 1534 and 1763, what is now Quebec was the List of French possessions and colonies, French colony of ''Canada (New France), Canada'' and was the most developed colony in New France. Following the Seven Years' War, ''Canada'' became a Territorial evolution of the British Empire#List of territories that were once a part of the British Empire, British colony, first as the Province of Quebec (1763–1791), Province of Quebec (1763–1791), then Lower Canada (1791–1841), and lastly part of the Province of Canada (1841–1867) as a result of the Lower Canada Rebellion. It was Canadian Confederation, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canada
Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of countries and dependencies by area, second-largest country by total area, with the List of countries by length of coastline, world's longest coastline. Its Canada–United States border, border with the United States is the world's longest international land border. The country is characterized by a wide range of both Temperature in Canada, meteorologic and Geography of Canada, geological regions. With Population of Canada, a population of over 41million people, it has widely varying population densities, with the majority residing in List of the largest population centres in Canada, urban areas and large areas of the country being sparsely populated. Canada's capital is Ottawa and List of census metropolitan areas and agglomerations in Canada, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myanmar
Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has a population of about 55 million. It is bordered by India and Bangladesh to its northwest, China to its northeast, Laos and Thailand to its east and southeast, and the Andaman Sea and the Bay of Bengal to its south and southwest. The country's capital city is Naypyidaw, and its largest city is Yangon (formerly Rangoon). Early civilisations in the area included the Tibeto-Burman-speaking Pyu city-states in Upper Myanmar and the Mon kingdoms in Lower Myanmar. In the 9th century, the Bamar people entered the upper Irrawaddy River, Irrawaddy valley, and following the establishment of the Pagan Kingdom in the 1050s, the Burmese language and Culture of Myanmar, culture and Buddhism in Myanmar, Theravada Buddhism slowly became dominant in the co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
