#calcium

• Akermanite — A mineral belonging to the melilite group, consisting of a complex calcium and magnesium silicate with the chemical formula Ca2MgSi2O7; it crystallizes in the tetragonal system and frequently occurs in silica-poor effusive igneous rocks, in contact-metamorphosed limestones, or as a major structural component in industrial metallurgical slags. This high-temperature mineral forms a continuous isomorphous series with gehlenite, being utilized in petrological studies to determine the thermodynamic conditions of magma solidification.
• Alkaline earth — Pertaining to or characteristic of the group of bivalent chemical elements in group 2 of the periodic table (such as beryllium, magnesium, calcium, strontium, barium, and radium). The name originates from the fact that the oxides of these metals exhibit pronounced alkaline properties and were historically called 'earths' due to their insolubility and high resistance to elevated temperatures.
• Alite — The main mineralogical and crystallo-chemical constituent of Portland cement clinker, consisting primarily of tricalcium silicate impure with small amounts of aluminum, iron, and magnesium oxides. Alite is responsible for setting and early strength development.
• Andradite — A mineral belonging to the silicate group and the garnet subgroup, chemically composed of calcium iron silicate. This structural mineral occurs in metamorphic rocks (especially skarns and crystalline limestones) and crystallizes in dodecahedral or trapezohedral forms with shades of yellow, green, brown, or black, being highly valued in its rare varieties (such as demantoid and melanite) as a gemstone.
• Anti-limescale — Preventing, reducing, or eliminating limescale (calcium carbonate) deposits from surfaces, pipes, or heating elements; a chemical substance or a magnetic or electronic device specially designed for water softening and the protection of household appliances. In an industrial and domestic sense, these agents dissolve the mineral matrix fixed inside installations, optimizing thermal transfer and preventing technical breakdowns.
• Anthracolitic — Belonging to, referring to, or specific to anthracolite or the geological period of formation of massive superior coal deposits combined with calcareous structures; a sedimentary rock or crystalline formation characterized by intercalations of calcium carbonate and organic fossil inclusions rich in fixed carbon. In a stratigraphic sense, it describes structural elements or petrographic layers that preserve physical and chemical properties from the Paleozoic era.
• Apatite — A mineral from the phosphate class, representing a natural calcium phosphate that contains fluorine, chlorine, or hydroxyl groups within its crystalline structure. This compound is widely used in industry as the primary raw material for producing phosphate fertilizers and phosphoric acid, while also being the most common phosphate mineral in the Earth's crust.
• Apatite — The standard literary and most frequent form of the name of the natural phosphate mineral; it also represents a major structural component of hard tissues in human and animal organisms, found as hydroxyapatite as the core mineral within the structure of tooth enamel and bones.
• Aragonite — A mineral from the natural carbonate class, representing an unstable crystalline form of calcium carbonate and a high-pressure polymorph of calcite. It crystallizes in the orthorhombic system, frequently forming long prismatic crystals, acicular aggregates, or specific encrustations such as flos ferri, and constitutes the primary mineral component making up the nacre of mollusk shells and fine pearls.
• Ardealite — A very rare secondary phosphate mineral, structurally composed of hydrated calcium phosphate-sulfate, with the chemical formula Ca2(PO4)(SO4)·4H2O. It typically forms as an alteration product in cave guano deposits through the reaction of acidic phosphate solutions with surrounding limestone, first discovered and described in 1932 in the Cioclovina Cave in Hunedoara County, Romania, from which it derives its name structurally linked to the Ardeal region.
• Arthrolith — A calcareous formation or mineralized calculus formed by the gradual accumulation and deposition of calcium salts inside a joint cavity or within the structure of the synovial capsule. This type of stony concretion, often secondary to chronic inflammatory processes or local metabolic disorders, acts as a foreign body that can cause constant mechanical irritation, hydrarthrosis, and progressive reduction of mobility.