Gypsum in the context of "Calcium"

Plaster is a building material used for the protective or decorative coating of walls and ceilings and for moulding and casting decorative elements. In English, "plaster" usually means a material used for the interiors of buildings, while "render" commonly refers to external applications. The term stucco refers to plasterwork that is worked in some way to produce relief decoration, rather than flat surfaces.

The most common types of plaster mainly contain either gypsum, lime, or cement, but all work in a similar way. The plaster is manufactured as a dry powder and is mixed with water to form a stiff but workable paste immediately before it is applied to the surface. The reaction with water liberates heat through crystallization and the hydrated plaster then hardens.

Assyrian sculpture is the sculpture of the ancient Assyrian states, especially the Neo-Assyrian Empire of 911 to 612 BC, which was centered around the city of Assur in Mesopotamia (modern-day Iraq) which at its height, ruled over all of Mesopotamia, the Levant and Egypt, as well as portions of Anatolia, Arabia and modern-day Iran and Armenia. It forms a phase of the art of Mesopotamia, differing in particular because of its much greater use of stone and gypsum alabaster for large sculpture.

Much the best-known works are the huge lamassu guarding entrance ways, and Assyrian palace reliefs on thin slabs of alabaster, which were originally painted, at least in part, and fixed on the wall all round the main rooms of palaces. Most of these are in museums in Europe or America, following a hectic period of excavations from 1842 to 1855, which took Assyrian art from being almost completely unknown to being the subject of several best-selling books, and imitated in political cartoons.

Mining in Japan is minimal because Japan does not possess many on-shore mineral resources. Many of the on-shore minerals have already been mined to the point that it has become less expensive to import minerals. There are small deposits of coal, oil, iron and minerals in the Japanese archipelago. Japan is scarce in critical natural resources and has been heavily dependent on imported energy and raw materials. There are major deep sea mineral resources in the seabed of Japan. This is not mined yet due to technological obstacles for deep sea mining.

In 2019, Japan was the 2nd largest world producer of iodine, 4th largest worldwide producer of bismuth, the world's 9th largest producer of sulfur and the 10th largest producer of gypsum.

Calcium sulfate (or calcium sulphate) is an inorganic salt with the chemical formula CaSO
₄. It occurs in several hydrated forms; the anhydrous state (known as anhydrite) is a white crystalline solid often found in evaporite deposits. Its dihydrate form is the mineral gypsum, which may be dehydrated to produce bassanite, the hemihydrate state. Gypsum occurs in nature as crystals (selenite) or fibrous masses (satin spar), typically colorless to white, though impurities can impart other hues. All forms of calcium sulfate are sparingly soluble in water and cause permanent hardness when dissolved therein.

Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed under the sea by the accumulation and lithification of hard parts of organisms, mostly microscopic plankton, which had settled to the sea floor. Chalk is common throughout Western Europe, where deposits underlie parts of France, and steep cliffs are often seen where they meet the sea in places such as the Dover cliffs on the Kent coast of the English Channel.

Chalk is mined for use in industry, such as for quicklime, bricks and builder's putty, and in agriculture, for raising pH in soils with high acidity. It is also used for "blackboard chalk" for writing and drawing on various types of surfaces, although these can also be manufactured from other carbonate-based minerals, or gypsum.

Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th century by Joseph Aspdin, and is usually made from limestone. It is a fine powder, produced by heating limestone and clay minerals in a kiln to form clinker, and then grinding the clinker with the addition of several percent (often around 5%) gypsum. Several types of Portland cement are available. The most common, historically called ordinary Portland cement (OPC), is grey, but white Portland cement is also available.

The cement was so named by Joseph Aspdin, who obtained a patent for it in 1824, because, once hardened, it resembled the fine, pale limestone known as Portland stone, quarried from the windswept cliffs of the Isle of Portland in Dorset. Portland stone was prized for centuries in British architecture and used in iconic structures such as St Paul's Cathedral and the British Museum.

Alabaster is a soft rock used for carvings and as a source of plaster powder. Archaeologists, geologists, and the stone industry have different definitions for the word alabaster. In archaeology, the term alabaster includes objects and artefacts made from two different minerals: (i) the fine-grained, massive type of gypsum, and (ii) the fine-grained, banded type of calcite.

Chemically, gypsum is a hydrous sulfate of calcium, whereas calcite is a carbonate of calcium. As types of alabaster, gypsum and calcite have similar properties, such as light color, translucence, and soft stones that can be carved and sculpted; thus the historical use and application of alabaster for the production of carved, decorative artefacts and objets d’art. Calcite alabaster also is known as onyx-marble, Egyptian alabaster, and Oriental alabaster, which terms usually describe either a compact, banded travertine stone or a stalagmitic limestone colored with swirling bands of cream and brown.

The Cretaceous–Paleogene (K–Pg) extinction event, formerly known as the Cretaceous-Tertiary (K–T) extinction event, was a major mass extinction of three-quarters of the plant and animal species on Earth approximately 66 million years ago. The event caused the extinction of all non-avian dinosaurs. Most other tetrapods weighing more than 25 kg (55 lb) also became extinct, with the exception of some ectothermic species such as sea turtles and crocodilians. It marked the end of the Cretaceous period, and with it the Mesozoic era, while heralding the beginning of the current geological era, the Cenozoic Era. In the geologic record, the K–Pg event is marked by a thin layer of sediment called the K–Pg boundary or K–T boundary, which can be found throughout the world in marine and terrestrial rocks. The boundary clay shows unusually high levels of the metal iridium, which is more common in asteroids than in the Earth's crust.

As originally proposed in 1980 by a team of scientists led by Luis Alvarez and his son Walter, it is now generally thought that the K–Pg extinction resulted from the impact of a massive asteroid 10 to 15 km (6 to 9 mi) wide, 66 million years ago, causing the Chicxulub impact crater and devastating the global environment, mainly through a lingering impact winter which halted photosynthesis in plants and plankton. The impact hypothesis, also known as the Alvarez hypothesis, was bolstered by the discovery of the 180 km (112 mi) Chicxulub crater in the Gulf of Mexico's Yucatán Peninsula in the early 1990s. The temporal match between the ejecta layer, and the onset of the extinctions and the agreement of ecological patterns in the fossil record with modeled environmental perturbations (for example, darkness and cooling), lead to the conclusion that the Chicxulub impact triggered the mass extinction. A 2016 drilling project into the Chicxulub peak ring confirmed that the peak ring comprised granite ejected within minutes from deep in the Earth, but contained hardly any gypsum, the usual sulfate-containing sea floor rock in the region: the gypsum would have vaporized and dispersed as an aerosol into the atmosphere, causing longer-term effects on the climate and food chain. In October 2019, researchers proposed the mechanisms of the mass extinction, arguing that the Chicxulub asteroid impact event rapidly acidified the oceans and produced long-lasting effects on the climate.