anhydrite


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Related to anhydrite: apatite

anhydrite

[an′hī‚drīt]
(mineralogy)
CaSO4 A mineral that represents gypsum without its water of crystallization, occurring commonly in white and grayish granular to compact masses; the hardness is 3-3.5 on Mohs scale, and specific gravity is 2.90-2.99. Also known as cube spar.

anhydrite

A natural mineral calcium sulfate, used in the manufacture of portland cement to control its set.
References in periodicals archive ?
Thus in this clinker is present in a large amount is not metabolized anhydrite (d = 3,50; 2,85 [Angstrom]).
The dolomitic part of K1 is characterized to be mudstone, mudstone to packstone, beige, moderately hard to hard, crystalline to cryptocrystalline, have occasional pelloids, pebbles and shell fragments, have local mudcracks in mudstone, slightly argillaceous in parts, have thin layers of anhydrite and o have good to fair vuggy and intercrystalline porosity.
On the other hand, it is observed that a certain quantity of anhydrite still remains in the sample of A1 and A3, even after 180 days of hydration, which can be related to the presence of anhydrite insoluble in these ashes.
Anhydrite has been noted by Cummings (1987) as rare, but no specimens attributable to the Fanwood quarry have been seen by the author.
Since the comprehensive studies on swelling of sulphate-bearing rocks were published by Sahores (1962) it has been generally accepted that two uncoupled mechanisms occur when anhydritic-gypsiferous claystones are soaked: (i) a short term "physical swelling" --due to the expansion of clayey host matrix--, and (ii) a long term "chemical swelling"--due to the transformation of anhydrite into gypsum in an thermodynamically open system, with a volumetric increase of approximately 62%, as shown in figure 1.
Another common feature from the upper part of the Eel Bed is nodular anhydrite with 5-30 mm long blebs, whose lower sides are always lined with dark algal mats.
Sulphate minerals are limited to gypsum and small amounts of anhydrite (XRD), although some celestite was also observed in the petrographic examinations.
Generally, anhydrite concentration is somewhat lower in PF-ashes, being highest in electrostatic precipitator ones.
And they did not contain anhydrite, a common vent chimney mineral that dissolves in seawater at temperatures less than about 150[degrees]C (302[degrees]F).
The unit is recognized as a formation, the Bass Islands Dolomite, in the subsurface, where it is defined as the interval suprajacent to the uppermost anhydrite of the G unit of the Salina and subjacent to the Silurian-Devonian unconformity.
Black smoker chimneys precipitate copper-iron sulphides and anhydrite on mixing with ambient temperature sea water, while lower temperature hydrothermal flows (typically 260-300 [degrees] C) precipitate iron-zinc sulphides and silica.