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Comenditic
Comendite is a hard, peralkaline igneous rock, a type of light blue grey rhyolite. Phenocrysts are sodic sanidine with minor albite and bipyramidal quartz. Iddings, Joseph Paxson, 1913, ''Igneous rocks: composition, texture and classification'', v. 2, pp. 94-96 Comendite occurs in the mountains Tibrogargan, Coonowrin, Tunbubudla, Coochin, Saddleback, Tibberoowuccum and Ngungun in the Glass House Mountains, South East Queensland, Australia. The blue colour is caused by very small crystals of riebeckite or arfvedsonite. Comendite also occurs in Sardinia, Corsica, Ascension Island, Ethiopia, Somalia and other areas of East Africa. The 1903 eruption of Changbaishan volcano in north-east China erupted comendite pumice. Comendite derives its name from the area of Le Commende on San Pietro Island San Pietro Island (Italian: ''Isola di San Pietro'', Ligurian Tabarchino: ''Uiza de San Pé'', Sardinian: ''Isula 'e Sàntu Pèdru'') is an island approximately off the South western Coa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comendite Rjw
Comendite is a hard, peralkaline igneous rock, a type of light blue grey rhyolite. Phenocrysts are sodic sanidine with minor albite and bipyramidal quartz. Iddings, Joseph Paxson, 1913, ''Igneous rocks: composition, texture and classification'', v. 2, pp. 94-96 Comendite occurs in the mountains Tibrogargan, Coonowrin, Tunbubudla, Coochin, Saddleback, Tibberoowuccum and Ngungun in the Glass House Mountains, South East Queensland, Australia. The blue colour is caused by very small crystals of riebeckite or arfvedsonite. Comendite also occurs in Sardinia, Corsica, Ascension Island, Ethiopia, Somalia and other areas of East Africa. The 1903 eruption of Changbaishan volcano in north-east China erupted comendite pumice. Comendite derives its name from the area of Le Commende on San Pietro Island San Pietro Island (Italian: ''Isola di San Pietro'', Ligurian Tabarchino: ''Uiza de San Pé'', Sardinian: ''Isula 'e Sàntu Pèdru'') is an island approximately off the South western Coa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arfvedsonite
Arfvedsonite () is a sodium amphibole mineral with composition: aNa2] Fe2+)4Fe3+(OH)2, Si8O22]. It crystallizes in the monoclinic prismatic crystal system and typically occurs as greenish black to bluish grey fibrous to radiating or stellate prisms. It is a rather rare mineral occurring in nepheline syenite intrusions and agpaitic (peralkaline) pegmatites and granites as the Golden Horn batholith in Okanogan County, Washington (type locality for zektzerite). Occurrences include Mont Saint-Hilaire, Quebec, Canada; the Ilímaussaq complex in Southern Greenland; and in pegmatites of the Kola Peninsula, Russia. Its mineral association includes nepheline, albite, aegirine, riebeckite, katophorite and quartz. Arfvedsonite was discovered in 1823 and named for the Swedish chemist Johan August Arfwedson (1792–1841). See also * List of minerals * List of minerals named after people This is a list of minerals named after people. The chemical composition follows name. A *Abe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pumice
Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular volcanic rock that differs from pumice in having larger vesicles, thicker vesicle walls, and being dark colored and denser.Jackson, J.A., J. Mehl, and K. Neuendorf (2005) ''Glossary of Geology'' American Geological Institute, Alexandria, Virginia. 800 pp. McPhie, J., M. Doyle, and R. Allen (1993) ''Volcanic Textures A guide to the interpretation of textures in volcanic rocks'' Centre for Ore Deposit and Exploration Studies, University of Tasmania, Hobart, Tasmania..198 pp. Pumice is created when super-heated, highly pressurized rock is violently ejected from a volcano. The unusual foamy configuration of pumice happens because of simultaneous rapid cooling and rapid depressurization. The depressurization creates bubbles by lowering the solubi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baekdu Mountain
Paektu Mountain (), also known as Baekdu Mountain and in China as Changbai Mountain ( zh, s=长白山, t=長白山; Manchu: Golmin Šanggiyan Alin), is an active stratovolcano on the Chinese–North Korean border. At , it is the highest mountain of the Baekdudaegan and Changbai ranges. Koreans assign a mythical quality to the volcano and its caldera lake, considering it to be their country's spiritual home. It is the highest mountain in North Korea and Northeast China. A large crater lake, called Heaven Lake, is in the caldera atop the mountain. The caldera was formed by the VEI 7 "Millennium" or "Tianchi" eruption of 946, which erupted about of tephra. This was one of the largest and most violent eruptions in the last 5,000 years (alongside the Minoan eruption, the Hatepe eruption of Lake Taupō in around AD 180, the 1257 eruption of Mount Samalas near Mount Rinjani and the 1815 eruption of Tambora). The mountain plays an important mythological and cultural and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
East Africa
East Africa, Eastern Africa, or East of Africa, is the eastern subregion of the African continent. In the United Nations Statistics Division scheme of geographic regions, 10-11-(16*) territories make up Eastern Africa: Due to the historical Omani Empire and colonial territories of the British East Africa Protectorate and German East Africa, the term ''East Africa'' is often (especially in the English language) used to specifically refer to the area now comprising the three countries of Kenya, Tanzania, and Uganda. However, this has never been the convention in many other languages, where the term generally had a wider, strictly geographic context and therefore typically included Djibouti, Eritrea, Ethiopia, and Somalia.Somaliland is not included in the United Nations geoscheme, as it is internationally recognized as a part of Somalia. *Tanzania, Kenya, Uganda, Rwanda, Burundi, Democratic Republic of Congo and South Sudan are members of the East African Community. The firs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Somalia
Somalia, , Osmanya script: 𐒈𐒝𐒑𐒛𐒐𐒘𐒕𐒖; ar, الصومال, aṣ-Ṣūmāl officially the Federal Republic of SomaliaThe ''Federal Republic of Somalia'' is the country's name per Article 1 of thProvisional Constitution, (; ), is a country in the Horn of Africa. The country is bordered by Ethiopia to the west, Djibouti to the northwest, the Gulf of Aden to the north, the Indian Ocean to the east, and Kenya to the southwest. Somalia has the longest coastline on Africa's mainland. Its terrain consists mainly of plateaus, plains, and highlands. Hot conditions prevail year-round, with periodic monsoon winds and irregular rainfall. Somalia has an estimated population of around million, of which over 2 million live in the capital and largest city Mogadishu, and has been described as Africa's most culturally homogeneous country. Around 85% of its residents are ethnic Somalis, who have historically inhabited the country's north. Ethnic minorities are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethiopia
Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east and northeast, Kenya to the south, South Sudan to the west, and Sudan to the northwest. Ethiopia has a total area of . As of 2022, it is home to around 113.5 million inhabitants, making it the 13th-most populous country in the world and the 2nd-most populous in Africa after Nigeria. The national capital and largest city, Addis Ababa, lies several kilometres west of the East African Rift that splits the country into the African and Somali tectonic plates. Anatomically modern humans emerged from modern-day Ethiopia and set out to the Near East and elsewhere in the Middle Paleolithic period. Southwestern Ethiopia has been proposed as a possible homeland of the Afroasiatic langua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ascension Island
Ascension Island is an isolated volcanic island, 7°56′ south of the Equator in the South Atlantic Ocean. It is about from the coast of Africa and from the coast of South America. It is governed as part of the British Overseas Territory of Saint Helena, Ascension and Tristan da Cunha, of which the main island, Saint Helena, is around to the southeast. The territory also includes the sparsely populated Tristan da Cunha archipelago, to the south, about halfway to the Antarctic Circle. Named after the day of its recorded discovery, Ascension of Jesus, Ascension Island was an important safe haven as a coaling station to mariners and a refueling stop for commercial airliners back in the days of international air travel by flying boats. Ascension Island was garrisoned by the British Admiralty from 22 October 1815 to 1922. During World War II, it was an important naval and air station, especially providing antisubmarine warfare bases in the Battle of the Atlantic.Victory at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corsica
Corsica ( , Upper , Southern ; it, Corsica; ; french: Corse ; lij, Còrsega; sc, Còssiga) is an island in the Mediterranean Sea and one of the 18 regions of France. It is the fourth-largest island in the Mediterranean and lies southeast of the French mainland, west of the Italian Peninsula and immediately north of the Italian island of Sardinia, which is the land mass nearest to it. A single chain of mountains makes up two-thirds of the island. , it had a population of 349,465. The island is a territorial collectivity of France. The regional capital is Ajaccio. Although the region is divided into two administrative departments, Haute-Corse and Corse-du-Sud, their respective regional and departmental territorial collectivities were merged on 1 January 2018 to form the single territorial collectivity of Corsica. As such, Corsica enjoys a greater degree of autonomy than other French regional collectivities; for example, the Corsican Assembly is permitted to exercise limit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sardinia
Sardinia ( ; it, Sardegna, label=Italian, Corsican and Tabarchino ; sc, Sardigna , sdc, Sardhigna; french: Sardaigne; sdn, Saldigna; ca, Sardenya, label=Algherese and Catalan) is the second-largest island in the Mediterranean Sea, after Sicily, and one of the 20 regions of Italy. It is located west of the Italian Peninsula, north of Tunisia and immediately south of the French island of Corsica. It is one of the five Italian regions with some degree of domestic autonomy being granted by a special statute. Its official name, Autonomous Region of Sardinia, is bilingual in Italian and Sardinian: / . It is divided into four provinces and a metropolitan city. The capital of the region of Sardinia — and its largest city — is Cagliari. Sardinia's indigenous language and Algherese Catalan are referred to by both the regional and national law as two of Italy's twelve officially recognized linguistic minorities, albeit gravely endangered, while the regional law provides ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Riebeckite
Riebeckite is a sodium-rich member of the amphibole group of silicate minerals, chemical formula Na2(Fe2+3Fe3+2)Si8O22(OH)2. It forms a solid solution series with magnesioriebeckite. It crystallizes in the monoclinic system, usually as long prismatic crystals showing a diamond-shaped cross section, but also in fibrous, bladed, acicular, columnar, and radiating forms. Its Mohs hardness is 5.0–6.0, and its specific gravity is 3.0–3.4. Cleavage is perfect, two directions in the shape of a diamond; fracture is uneven, splintery. It is often translucent to nearly opaque. Name and discovery Riebeckite was first described in 1888 for an occurrence on Socotra Island, Aden Governorate, Yemen, and named for German explorer Emil Riebeck (1853–1885). The mineral is also known as crocidolite. Occurrence Riebeckite typically forms dark-blue elongated to fibrous crystals in highly alkali granites, syenites, rarely in felsic volcanics, granite pegmatites and schist. It occurs in banded i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peralkaline
Peralkaline rocks include those igneous rocks which have a deficiency of aluminium such that sodium and potassium are in excess of that needed for feldspar. The presence of aegerine (sodium pyroxene) and riebeckite (sodium amphibole) are indicative of peralkaline conditions. Examples are the peralkaline rhyolites, comendite and pantellerite, with comendite being the more felsic (silica-rich) rock. Another example is the peralkaline granite that forms the islet of Rockall in the North Atlantic Ocean. Peralkaline rocks are indicative of continental rift-related volcanicity (e.g. the peralkaline rhyolites of the East African Rift in central Kenya) as well as continental and oceanic hotspot volcanicity (e.g. the peralkaline rhyolites of the Glass House Mountains in eastern Australia and the Canary Islands in the Atlantic Ocean). Peralkaline rocks related to subduction zone volcanicity have also been reported (e.g. Sardinia in Italy). Peralkaline magmas likely form when fractional crys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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