Definition of anhydrite in English:



  • [mass noun] A white mineral consisting of anhydrous calcium sulphate. It typically occurs in evaporite deposits.

    • ‘Both Ara Group pyrite and anhydrite are characterized by highly variable [delta] 34 S values.’
    • ‘In these cases, associated fluids could have modified the original isotopic signature, in particular when anhydrite was altered to secondary gypsum by surface waters.’
    • ‘The lower, evaporitic part of each cycle contains halite, anhydrite (secondary after sedimentary gypsum), and high salts (sylvite and polyhalite).’
    • ‘The changes of [delta] 34 S anhydrite within hydrological cycles seem to be related to changes in the water mass during such a cycle.’
    • ‘Middle Triassic anhydrite and dolomite form a sequence of strong reflectors, as does Lower Cretaceous sandstone.’
    • ‘Bacterial sulphate reduction was the dominant process controlling [delta] 34 S of Ara Group anhydrite and pyrite.’
    • ‘Small crystals of insoluble residual minerals such as anhydrite, chambersite, hilgardite, and hilgardite - 3Tc were caught up in the brines pumped back to the surface.’
    • ‘Only minor fractionation of sulphur isotopes is associated with the precipitation of most sulphate minerals, and no change in [delta] 34 S occurs during the dehydration of gypsum to anhydrite.’
    • ‘Layering is defined by halite of different colours and grain size with various concentrations of different impurities (mainly red clay, buff anhydrite or green volcanic rocks).’
    • ‘New [delta] 34 S data from anhydrite and pyrite of the Ara Group in Oman extend this record to Arabia.’
    • ‘At depths of less than 600m (up to 1000m depending on temperature and fluid composition), gypsum forms rather than anhydrite because the gypsum-anhydrite stability boundary is crossed somewhere in this interval.’
    • ‘The Bonneval gneiss is separated from the augen gneiss by a fault zone in which dolomite, cargneule, anhydrite and Bündnerschiefer occur.’
    • ‘Tubes composed of concentric bands of agate can result from elongated crystals, such as anhydrite or selenite, that formed early in the agatization process and were subsequently dissolved and replaced by silica.’
    • ‘It is dominated by the deposition of calcite with minor pyrite, marcasite, barite, anhydrite and gypsum.’
    • ‘In the Mesozoic, and into the Paleocene, limestone and dolomite interbedded with shale, clay and anhydrite prevailed in a more restricted, shallow marine to lagoonal environment.’
    • ‘Sulfate is derived almost invariably from the dissolution of primary or secondary gypsum and/or anhydrite at or near the redox-reaction site (s).’
    • ‘Gypsum and anhydrite are closely related; both are calcium minerals and both are formed early (after carbonate) in the sequence of minerals when sea water is evaporated or in sabkha environments, as in the present-day Persian Gulf.’
    • ‘Calcium sulfate exists in two forms, as anhydrite and as gypsum.’
    • ‘Resetting of the [delta] 34 S values in anhydrite and pyrite by diagenetic fluids seems unlikely in the present case, because diagenesis occurred in a largely closed system and did not involve significant fluid movement.’
    • ‘These cores were composed of the mineral anhydrite and contained a type of fossil known as stromatolite. Anhydrite is found only on arid coastal flats in a dry environment known as sabhka.’


Early 19th century: from Greek anudros (see anhydrous)+ -ite.