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Thorianite
Thorianite is a rare thorium oxide mineral, ThO2. It was originally described by Ananda Coomaraswamy in 1904 as uraninite, but recognized as a new species by Wyndham R. Dunstan. It was so named by Dunstan on account of its high percentage of thorium; it also contains the oxides of uranium, lanthanum, cerium, praseodymium and neodymium. Helium is present, and the mineral is slightly less radioactive than pitchblende, but is harder to shield due to its high energy gamma rays. It is common in the alluvial gem-gravels of Sri Lanka, where it occurs mostly as water worn, small, heavy, black, cubic crystals. The largest crystals are usually near 1.5 cm. Larger crystals, up to , have been reported from Madagascar. Chemistry Based on color, specific gravity and composition three types of thorianite are distinguished: *α-thorianite *β-thorianite *γ-thorianite Thorianite and uraninite form a complete solid solution series in synthetic and natural material. The division between the t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thorium
Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high melting point. Thorium is an electropositive actinide whose chemistry is dominated by the +4 oxidation state; it is quite reactive and can ignite in air when finely divided. All known thorium isotopes are unstable. The most stable isotope, 232Th, has a half-life of 14.05 billion years, or about the age of the universe; it decays very slowly via alpha decay, starting a decay chain named the thorium series that ends at stable 208 Pb. On Earth, thorium and uranium are the only significantly radioactive elements that still occur naturally in large quantities as primordial elements. Thorium is estimated to be over three times as abundant as uranium in the Earth's crust, and is chiefly refined from monazite sands as a by-product of extracti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thorium Oxide
Thorium dioxide (ThO2), also called thorium(IV) oxide, is a crystalline solid, often white or yellow in colour. Also known as thoria, it is produced mainly as a by-product of lanthanide and uranium production. Thorianite is the name of the mineralogical form of thorium dioxide. It is moderately rare and crystallizes in an isometric system. The melting point of thorium oxide is 3300 °C – the highest of all known oxides. Only a few elements (including tungsten and carbon) and a few compounds (including tantalum carbide) have higher melting points. All thorium compounds, including the dioxide, are radioactive because there are no stable isotopes of thorium. Structure and reactions Thoria exists as two polymorphs. One has a fluorite crystal structure. This is uncommon among binary dioxides. (Other binary oxides with fluorite structure include cerium dioxide, uranium dioxide and plutonium dioxide.) The band gap of thoria is about 6 eV. A tetragonal form of thoria is also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxide Mineral
The oxide mineral class includes those minerals in which the oxide anion (O2−) is bonded to one or more metal alloys. The hydroxide-bearing minerals are typically included in the oxide class. The minerals with complex anion groups such as the silicates, sulfates, carbonates and phosphates are classed separately. Simple oxides: *XO **Periclase group ***Periclase ***Manganosite **Zincite group ***Zincite *** Bromellite ***Tenorite ***Litharge * **Cuprite **Ice * **Hematite group ***Corundum ***Hematite ***Ilmenite * **Rutile group ***Rutile ***Pyrolusite ***Cassiterite **Baddeleyite **Uraninite **Thorianite * **Spinel group ***Spinel ***Gahnite ***Magnetite ***Franklinite ***Chromite **Chrysoberyl **Columbite *Hydroxide subgroup: **Brucite **Manganite ** Romanèchite **Goethite group: ***Diaspore ***Goethite Nickel–Strunz Classification -04- Oxides IMA-CNMNC proposes a new hierarchical scheme (Mills et al., 2009). This list uses it to modify ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Travancore
The Kingdom of Travancore ( /ˈtrævənkɔːr/), also known as the Kingdom of Thiruvithamkoor, was an Indian kingdom from c. 1729 until 1949. It was ruled by the Travancore Royal Family from Padmanabhapuram, and later Thiruvananthapuram. At its zenith, the kingdom covered most of the south of modern-day Kerala ( Idukki, Kottayam, Alappuzha, Pathanamthitta, Kollam, and Thiruvananthapuram districts, and some portions of Ernakulam district), and the southernmost part of modern-day Tamil Nadu (Kanyakumari district and some parts of Tenkasi district) with the Thachudaya Kaimal's enclave of Irinjalakuda Koodalmanikyam temple in the neighbouring Kingdom of Cochin. However Tangasseri area of Kollam city and Anchuthengu near Attingal in Thiruvananthapuram district, were British colonies and were part of the Malabar District until 30 June 1927, and Tirunelveli district from 1 July 1927 onwards. Travancore merged with the erstwhile princely state of Cochin to form Travancore-Cochin i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the south, the Arabian Sea on the southwest, and the Bay of Bengal on the southeast, it shares land borders with Pakistan to the west; China, Nepal, and Bhutan to the north; and Bangladesh and Myanmar to the east. In the Indian Ocean, India is in the vicinity of Sri Lanka and the Maldives; its Andaman and Nicobar Islands share a maritime border with Thailand, Myanmar, and Indonesia. Modern humans arrived on the Indian subcontinent from Africa no later than 55,000 years ago., "Y-Chromosome and Mt-DNA data support the colonization of South Asia by modern humans originating in Africa. ... Coalescence dates for most non-European populations average to between 73–55 ka.", "Modern human beings—''Homo sapiens''—originated in Africa. Then, int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sabaragamuwa
The Sabaragamuwa Province ( si, සබරගමුව පළාත ''Sabaragamuwa Paḷāta'', ta, சபரகமுவ மாகாணம் ''Sabaragamuwa Mākāṇam'') is one of the nine provinces of Sri Lanka, the first level administrative division of the country. The provinces have existed since the 19th century but did not have any legal status until 1987 when the 13th Amendment to the Constitution of Sri Lanka established provincial councils. The Sabaragamuwa Province contains two districts: Ratnapura and Kegalle. It is named after its former indigenous inhabitants, namely the Sabara, an indic term for hunter-gatherer tribes, a term seldom used in ancient Sri Lanka. Sabaragamuwa University is in Belihuloya. Districts Sabaragamuwa is divided into 2 districts: * Kegalle District * Ratnapura District Municipal Council * Ratnapura Urban Council * Balangoda * Embilipitiya * Kegalle Other Towns * Bulathkohupitiya * Belihuloya * Eheliyagoda * Kalawana * Kuruwita * Maw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Balangoda
Balangoda is a large town in Ratnapura District, Sabaragamuwa Province, Sri Lanka, governed by an urban council located away from Colombo and from Ratnapura on Colombo - Batticaloa Highway(A4). It is one of the largest towns of the Sabaragamuwa Province. According to the 2001 census, Balangoda has a population of 16,875 and area of . Balangoda is notable due to the discovery of skeletal Hominini remains from the late Quaternary period (the earliest reliably dated record of anatomically modern humans in South Asia). The town is also the birthplace of Balangoda Ananda Maitreya Thero and Sirimavo Bandaranaike (the world's first female head of government) the Prime Minister of Sri Lanka (1960–65, 1970–77 and 1994–2000). Balangoda is situated in the hilly central region of central Sri Lanka on Sabaragamuwa Mountain Range. The main livelihoods of this region are farming (vegetables, fruits, and spices), rice cultivation for mainly local consumption, tea cultivation for interna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galle
Galle ( si, ගාල්ල, translit=Gālla; ta, காலி, translit=Kāli) (formerly Point de Galle) is a major city in Sri Lanka, situated on the southwestern tip, from Colombo. Galle is the provincial capital and largest city of Southern Province, Sri Lanka and is the capital of Galle District. Galle was known as ''Gimhathiththa'' before the arrival of the Portuguese in the 16th century, when it was the main port on the island. Ibn Batuta, a Moroccan Berber Muslim traveller in the 14th century, referred to it as ''Qali''. Galle reached the height of its development in the 18th century, during the Dutch colonial period. Galle is the best example of a fortified city built by the Portuguese in South and Southeast Asia, showing the interaction between Portuguese architectural styles and native traditions. The city was extensively fortified by the Dutch during the 17th century from 1649 onwards. The Galle fort is a world heritage site and is the largest remaining fortres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pegmatites
A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic composition to granite. However, rarer intermediate composition and mafic pegmatites are known. Many of the world's largest crystals are found within pegmatites. These include crystals of microcline, quartz, mica, spodumene, beryl, and tourmaline. Some individual crystals are over long. Most pegmatites are thought to form from the last fluid fraction of a large crystallizing magma body. This residual fluid is highly enriched in volatiles and trace elements, and its very low viscosity allows molecules to migrate rapidly to join an existing crystal rather than coming together to form new crystals. This allows a few very large crystals to form. While most pegmatites have a simple composition of minerals common in ordinary igneous rock, a few pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rare Earths
The rare-earth elements (REE), also called the rare-earth metals or (in context) rare-earth oxides or sometimes the lanthanides (yttrium and scandium are usually included as rare earths), are a set of 17 nearly-indistinguishable lustrous silvery-white soft heavy metals. Compounds containing rare earths have diverse applications in electrical and electronic components, lasers, glass, magnetic materials, and industrial processes. Scandium and yttrium are considered rare-earth elements because they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties, but have different electronic and magnetic properties. These metals tarnish slowly in air at room temperature and react slowly with cold water to form hydroxides, liberating hydrogen. They react with steam to form oxides, and at elevated temperature (400°C) ignite spontaneously. These elements and their compounds have no biological function other than in several specialized enzymes, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
