|
Comendite
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 The blue colour is caused by very small crystals of riebeckite or arfvedsonite. The 1903 eruption of Baekdu Mountain, Changbaishan volcano in northeast China erupted comendite pumice. Comendite derives its name from the area of Le Commende on San Pietro Island in Italy, where the rock type is found.Cioni, R. and Funedda, A., (2005) ''Structural geology of crystal-rich, silicic lava flows: A case study from San Pietro Island (Sardinia, Italy)'' in Manga, M. and Ventura, G. (editors) (2005) ''Kinematics and Dynamics of Lava Flows'', Geological Society of America Special Paper 396, pages 1 to 14. Comendite also occurs in the Glass House Mountains of southeast Queensland, Australia, as well as in Sardinia, Corsica, Ascension Is ... [...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 fractiona ... [...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] |
Glass House Mountains
The Glass House Mountains are a cluster of thirteen hills that rise abruptly from the coastal plain on the Sunshine Coast, Queensland, Sunshine Coast, Queensland, Australia. The highest hill is Mount Beerwah at 556 metres above sea level, but the most identifiable of all the hills is Mount Tibrogargan which from certain angles bears a resemblance to a gorilla facing east towards the ocean. The Glass House Mountains are located near Beerburrum State Forest and Steve Irwin Way. From Brisbane, the mountains can be reached by following the Bruce Highway north and taking the Glass House Mountains tourist drive turn-off onto Steve Irwin Way. The trip is about one hour from Brisbane. The Volcanic peaks of the Glass House Mountains rise dramatically from the surrounding Sunshine Coast landscape. They were formed by intrusive plugs, remnants of volcanic activity that occurred 26–27 million years ago. Molten rock filled small vents or intruded as bodies beneath the surface and solidified ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Pietro Island
San Pietro Island (Italian language, Italian: ''Isola di San Pietro'', Ligurian (Romance language), Ligurian Tabarchino: ''Uiza de San Pé'', Sardinian language, Sardinian: ''Isula 'e Sàntu Pèdru'') is an island approximately off the South western Coast of Sardinia, Italy, facing the Sulcis peninsula. With an area of it is the sixth-largest island of Italy by area. The approximately 6,000 inhabitants are mostly concentrated in the fishing town of Carloforte, the only ''comune'' in the island. It is included in the province of South Sardinia. It is named after Saint Peter. The island is connected by regular ferry service to Portovesme and Calasetta. Geography The island is of volcanic origin. The rocks are of Cenozoic age, and include basalt, dacite and rhyolite (including the peralkaline variety comendite). The of its coasts are mostly rocky; the western and northern part includes some natural grottoes, unprotected landings, with a few small beaches, in general here the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Somalia
Somalia, officially the Federal Republic of Somalia, is the easternmost country in continental Africa. The country is located in the Horn of Africa and is bordered by Ethiopia to the west, Djibouti to the northwest, Kenya to the southwest, the Gulf of Aden to the north, and the Indian Ocean to the east. Somalia has the longest coastline on Africa's mainland. Somalia has an estimated population of 18.1 million, of which 2.7 million live in the capital and largest city, Mogadishu. Around 85% of Somalia's residents are ethnic Somali people, Somalis. The official languages of the country are Somali language, Somali and Arabic, though Somali is the Languages of Somalia, primary language. Somalia has historic and religious ties to the Arab world. The people in Somalia are mainly Muslims, following the Sunni Islam, Sunni branch.. In antiquity, Somalia was an important commercial center. During the Middle Ages, several powerful Somali empires dominated the regional trade, including th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethiopia
Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Kenya to the south, South Sudan to the west, and Sudan to the northwest. Ethiopia covers a land area of . , it has around 128 million inhabitants, making it the List of countries and dependencies by population, thirteenth-most populous country in the world, the List of African countries by population, second-most populous in Africa after Nigeria, and the most populous landlocked country on Earth. The national capital and largest city, Addis Ababa, lies several kilometres west of the East African Rift that splits the country into the African Plate, African and Somali Plate, Somali tectonic plates. Early modern human, Anatomically modern humans emerged from modern-day Ethiopia and set out for the Near East and elsewhere in the Middle Paleolithi ... [...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 Atlantic Ocean, 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 Territories, 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. The discovery of Ascension by Joao da Nova in 1501 was described by two Portuguese chroniclers who probably misnamed it as Conception Island. The popular idea that Ascension was rediscovered by Afonso de Albuquerque in 1503 is probably wrong, Ascension having been long confused with Trindade and Martim Vaz, Trindade. Ascension Island was garrisoned by the British Admiralty from 22 October 1815 to 1922 and was an important refueling stop for ships a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corsica
Corsica ( , , ; ; ) is an island in the Mediterranean Sea and one of the Regions of France, 18 regions of France. It is the List of islands in the Mediterranean#By area, fourth-largest island in the Mediterranean and lies southeast of the Metropolitan France#Hexagon, French mainland, west of the Italian Peninsula and immediately north of the Italian island of Sardinia, the nearest land mass. A single chain of mountains makes up two-thirds of the island. , it had a population of 355,528. The island is a Single territorial collectivity, territorial collectivity of France, and is expected to achieve "a form of autonomy" in the near future. The regional capital is Ajaccio. Although the region is divided into two administrative Departments of France, departments, Haute-Corse and Corse-du-Sud, their respective regional and departmental Territorial collectivity, territorial collectivities were merged on 1 January 2018 to form the single territorial collectivity of Corsica. Corsican aut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sardinia
Sardinia ( ; ; ) is the Mediterranean islands#By area, second-largest island in the Mediterranean Sea, after Sicily, and one of the Regions of Italy, twenty regions of Italy. It is located west of the Italian Peninsula, north of Tunisia and 16.45 km south of the French island of Corsica. It has over 1.5 million inhabitants as of 2025. It is one of the five Italian regions with some degree of Autonomous administrative division, domestic autonomy being granted by a Regions of Italy#Autonomous regions with special statute, special statute. Its official name, Autonomous Region of Sardinia, is bilingual in Italian language, Italian and Sardinian language, Sardinian: / . It is divided into four provinces of Italy, provinces and a Metropolitan cities of Italy, metropolitan city. Its capital (and largest city) is Cagliari. Sardinia's indigenous language and Algherese dialect, Algherese Catalan language, Catalan are referred to by both the regional and national law as two of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Queensland
Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south, respectively. To the east, Queensland is bordered by the Coral Sea and the Pacific Ocean; to the state's north is the Torres Strait, separating the Australian mainland from Papua New Guinea, and the Gulf of Carpentaria to the north-west. With an area of , Queensland is the world's List of country subdivisions by area, sixth-largest subnational entity; it List of countries and dependencies by area, is larger than all but 16 countries. Due to its size, Queensland's geographical features and climates are diverse, and include tropical rainforests, rivers, coral reefs, mountain ranges and white sandy beaches in its Tropical climate, tropical and Humid subtropical climate, sub-tropical c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baekdu Mountain
Paektu Mountain or Baekdu Mountain () is an active stratovolcano on the Chinese–North Korean border. In China, it is known as Changbai Mountain (). At , it is the tallest mountain in North Korea and Northeast China and the tallest mountain of the Baekdu-daegan and Changbai mountain ranges. The highest peak, called Janggun Peak, belongs to North Korea. The mountain notably has a caldera that contains a large crater lake called Heaven Lake, and is also the source of the Songhua, Tumen, and Yalu rivers. Korean and Manchu people assign a mythical quality to the mountain and its lake, and consider the mountain to be their ancestral homeland. The mountain's caldera was formed by an eruption in 946 that released about of tephra. The eruption was among the largest and most powerful eruptions on Earth in the last 5,000 years. The volcano last erupted in 1903, and is expected to erupt around every hundred years. In the 2010s, concerns over an upcoming eruption prompted several ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
