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Gypsum is a common mineral, with thick and extensive evaporite beds in association with sedimentary rocks. Deposits are known to occur in strata from as far back as the Archaean eon. [16] Gypsum is deposited from lake and sea water, as well as in hot springs, from volcanic vapors, and sulfate solutions in veins.
The main sources of calcium sulfate are naturally occurring gypsum and anhydrite, which occur at many locations worldwide as evaporites. These may be extracted by open-cast quarrying or by deep mining. World production of natural gypsum is around 127 million tonnes per annum. [17]
PT Semen Indonesia (Persero) Tbk (known as SIG) is a state-owned holding company providing building material solutions. The company has 17 subsidiaries located in Indonesia and Vietnam . With a market reach to Asia , Australia and Oceania , the company's main business is in the cement sector and its derivative products such as concrete , mortar ...
A gypsum block is made of gypsum plaster and water. The manufacturing process [1] is automated at production plants where raw gypsum (CaSO 4 ·2H 2 O) is ground and dried, then heated to remove three-quarters of the bound water and thus transformed into calcium sulfate hemihydrate (CaSO 4 ·½H 2 O), also known as gypsum plaster, stucco, calcined gypsum or plaster of Paris.
Selenitic lime, also known as Scotts' cement after Henry Young Darracott Scott, is a cement of grey chalk or similar lime, such as in the Lias Group, with about 5% added gypsum plaster (calcined gypsum). [13] Selenite is a type of gypsum, but selenitic cement may be made using any form of sulfate or sulfuric acid. [18]
The Truong Son and Luang Prabang structures converge in northern Laos, bordered by northwest trending fault-bounded structures such as Phu Hoat Massif. The Song Ma Anticlinorium near Vietnam exposes Proterozoic basement rock at the surface. The Yunnan-Malay fold belt originated from closure of two sedimentary basins and is a prominent feature.
Vietnam, [e] [f] officially the Socialist Republic of Vietnam, [g] [h] is a country at the eastern edge of mainland Southeast Asia, with an area of about 331,000 square kilometres (128,000 sq mi) and a population of over 100 million, making it the world's fifteenth-most populous country.
Indonesia, [c] officially the Republic of Indonesia, [d] is a country in Southeast Asia and Oceania, between the Indian and Pacific oceans. Comprising over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guinea, Indonesia is the world's largest archipelagic state and the 14th-largest country by area, at 1,904,569 square kilometres (735,358 square miles).