The gypsum–anhydrite paradox revisited
In this work we have established a framework to explain the contradictory observations of ubiquitous precipitation of gypsum in the anhydrite stability region in the …
Gypsum Anhydrite Mineralmundi
KGS--Geological Log Analysis--Evaporites
Representative outcrop of Nippewalla Group in Barber County, Kansas. Pale blue cap rock is composed of gypsum/anhydrite with some hematite. Underlying dark red rocks are siltstones and sandstones composed of quartz, hematite, and gypsum/anhydrite poorly cemented by easily dissolved halite. Note person in green coat for scale.
THE GYPSUM-ANHYDRITE EQUILIBRIUM AT ONE ATMOSPHERE …
The equilibrium temperature for the reaction CaSOr.2HgO:CaSO4+2FIrO(riq soh) has been determined as a function of activity of HzO (osro) of the solution. Synthetic gypsum and anhydrite or 1:1 mixtures were stirred in solutions of known osrs (calculated from vapor pressure data for the NarSOr and HzSOq solutions), at constant temperature {or as …
Gypsum Anhydrite Mining In The United States | The …
Top States by Gypsum Anhydrite Deposits In The United States. Total Prospects Occurrences Plants Producers. Arizona 22 3 7 - 12 California 7 2 1 - 4 Colorado 4 - 3 - 1 Idaho 2 - - - 2 Michigan 3 - - - 3 Nevada 24 6 3 - 15 New Mexico 2 - - - 2 New York 1 - 1 - - Texas 2 - - - 2 Utah 9 3 2 - 4 Washington 3 - 1 - 2
Quantitative determination of anhydrite III from dehydrated gypsum …
XRD-pattern of dehydrated gypsum with a) high anhydrite III content and b) high bassanite content. Calculated ICSD patterns of bassanite and anhydrite III [4] from Rietveld refinement. In Fig. 2 a the phase composition of samples G_85 to G_550 prepared under 7% relative humidity in a glove box and evaluated with the Rietveld method are …
Evidence of a new phase in gypsum–anhydrite …
This phase corresponds to the soluble stage of g-anhydrite, and it is characterized by a high ionic charge inside the crystal channels. T he complete sequence is gypsum - 0.625-subhydrate - bassanite - hydro g-anhydrite - anhydrous g-anhydrite - b-anhydrite. The transformation s were also assessed using DSC, TG,
Understanding gypsum in 3 diagrams
Gypsum is one of the most widely-used building materials in the world. It is applied in several interior building uses, including in wallboard. Normally, calcium sulphate dihydrate (CaSO 4 •2H 2 O) is used as a raw material and a subhydrate such as hemihydrate (CaSO 4 •0.5H 2 O) or anhydrite (CaSO 4) is produced. The subhydrate is …
The Gypsum—anhydrite Equilibrium at One Atmosphere …
The equilibrium temperature for the reaction CaSO 4 · 2 H 2 O = CaSO 4 +2H 2 O (liq. soln) has been determined as a function of activity of H 2 O (aH 2 O) of the solution. Synthetic gypsum and anhydrite or 1:1 mixtures were stirred in solutions of known2 O (calculated from vapor pressure data for the Na 2 SO 4 and H 2 S0 4 solutions), at …
Barite, Anhydrite and Gypsum Reference Materials for
Secondary ion mass spectrometry was used to test the δ 18 O and δ 34 S nanogram-scale homogeneity of a suite of candidate sulfate minerals, ultimately selecting three barite, two anhydrite, and two gypsum samples from the Royal Ontario Museum that have repeatabilities for their SIMS measurements of better than ±0.39‰ and ±0.37‰ …
Anhydrite Gypsum Contamination
The reaction between gypsum or anhydrite with soda ash is: Ca++ + SO +2 Na+ + CO3= ^ CaCO3 + 2Na+ + SO. Soluble sodium sulfate (Na+ + SO4 ions) is formed from this reaction and could cause flocculation problems after prolonged treatments. For this reason, it is generally necessary to convert to a calcium-based fluid when massive …
Anhydrite and gypsum | SpringerLink
A possible mechanism for the formation of marine anhydrite is reaction of early-precipitated gypsum with deeper-bottom brine pools of abnormal composition, as in the Red Sea, or …
Gypsum
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk chalk. ... As with anhydrite, the solubility of gypsum in saline solutions and in brines is also ...
Mechanisms for anhydrite and gypsum formation in the …
The Sr, Ba, and rare earth elements (REEs) concentrations and Sr isotopic composition of anhydrite and gypsum have been determined for samples from the Matsumine, Shakanai, and Hanaoka Kuroko-type massive sulfide–sulfate deposits of northern Japan to evaluate the mechanisms of sekko (anhydrite and gypsum) ore …
Making of anhydrite cement from waste gypsum
The transformation of anhydrite into gypsum, thus involves a dissolution — nucleation — growth process. Several workers have reported the use of chemical activators that increase the hydration rate of the solid anhydrite [26], [27], [28]. 4. Conclusions. 1. The stable anhydrite cement can be produced by heating phosphogypsum at 1000°C. 2.
Gypsum vs. Anhydrite: What's the Difference?
Gypsum, a widely used mineral, is known for its softness and is composed of calcium sulfate dihydrate. Anhydrite, on the other hand, is a hard mineral, the …
Anhydrite and gypsum | SpringerLink
Anhydrite (CaSO 4) and gypsum (CaSO 4 ·2H 2 O) are the two most abundant minerals of ancient marine evaporite deposits and are also common in non …
Transition of anhydrite into gypsum
The most common minerals in nature are: gypsum and anhydrite II, characteristic for various environments and places of occurrence, often sharing them or appearing separately (fig. 1) creates in different environments on the earth's surface during the evaporation of water with an appropriate degree of salinity, while the primary anhydrite most ...
Preparation of Large-grained anhydrite(VI) γ-CaSO4 with FGD gypsum
Highlights. Design a new method of high pressure salt solution for preparing large-grained anhydrite(VI) γ-CaSO 4.. Anhydrite(VI) γ-CaSO 4 with length of 120 μm and length–diameter ratio of 1 was prepared at slurry concentration of 18 wt%, succinic acid of 0.02 wt%, NaCl of 3.0 wt%, 1,4-butanediol of 0.712 wt%, reaction temperature of 120°C, …
A systematic review of Anhydrite-Bearing Reservoirs
1. Introduction. Anhydrite is a common reactive sulfate rock/mineral found in several underground reservoirs including sandstone, carbonate and shale rocks [52], [113], [125], [211].Anhydrite is also observed in carbonates as cap-rocks, nodules/small lumps, and cements [97], [125].One key example is the giant carbonate oil fields in the Middle …
What Lurks in the Martian Rocks and Soil? Investigations of …
This study of the spectral properties of Ca-sulfates was initiated to support remote detection of these minerals on Mars. Gypsum, bassanite, and anhydrite are the currently known forms of Ca-sulfates. They are typically found in sedimentary evaporites on Earth, but can also form via reaction of acidic fluids associated with volcanic activity. …
The Solubilities and Thermodynamic Equilibrium of Anhydrite and Gypsum
Anhydritic claystones consist of a clay matrix with finely distributed anhydrite. Their swelling has led to severe damage and high repair costs in several tunnels. Gypsum growth combined with water uptake by the clay minerals is the main cause of the swelling process. Identifying the conditions under which gypsum rather …
Mechanism and kinetics of gypsum–anhydrite
The transformation of gypsum into anhydrite at low temperatures under atmospheric pressure as well as at elevated temperatures (150 °C and 200 °C) inside an autoclave was investigated by monitoring changes in both the liquid and solid phases.The effect of temperature, sulfuric acid addition, anhydrite seeding and addition of sulfate …
Spectral properties of Ca-sulfates: Gypsum, bassanite, and anhydrite …
Gypsum and bassanite spectra exhibit characteristic and distinct triplet bands near 1.4–1.5 μm, a strong band near 1.93–1.94 μm, and multiple features near 2.1–2.3 μm attributed to H 2 O. Anhydrite, bassanite, and gypsum all have SO 4 combination and overtone features from 4.2–5 μm that are present in reflectance spectra.
Modeling Solubility of Anhydrite and Gypsum in Aqueous
Gypsum crystals nucleate on existing gypsum crystals and surfaces of clay minerals. The transformation of anhydrite into gypsum proceeds until all the anhydrite present in the rock is converted to gypsum. This process (gypsification of anhydrite) is accompanied by about 61% increase in volume (Butscher et al. 2011, 2017; Jarzyna et …
Gypsum-Anhydrite Equilibria in Systems CaSO4-H2O and …
Semantic Scholar extracted view of "Gypsum-Anhydrite Equilibria in Systems CaSO4-H2O and CaCO4-NaCl-H2O" by C. Blount et al. Skip to search form Skip to main content Skip to account menu. Semantic Scholar's Logo. Search 220,040,384 papers from all fields of science. Search ...
Gypsum and Anhydrite | Rock & Gem Magazine
Therefore, these two minerals often form mutual pseudomorphs, with gypsum exhibiting the external orthorhombic shape of anhydrite and anhydrite exhibiting the external monoclinic shape of gypsum. An interesting side-by-side example of these two forms of calcium sulfate is the blue angelite gem variety of massive anhydrite.
Gypsum, Anhydrite, Anhydrite Gypsum,Thailand Gypsum,Anhydrite,Anhydrite
General Mining and Trading Co.,Ltd. (GMT) is one of Thailand's leading Gypsum producers. We are also a producer of Anhydrite Gypsum producers. We are also a producer of Anhydrite Gypsum. The GMT has been established since 1989. We are growing everyday. Because of this, we become a stable company at the present.
Gypsum vs Anhydrite: Difference and Comparison
The difference between gypsum and anhydrite is that Gypsum is a mineral that is aqueous and contains 2 water molecules, while …
(PDF) Gypsum/anhydrite: Some engineering problems
The engineering properties of gypsum/anhydrite change as a consequence of groundwater, pressure and heat. Gypsum and anhydrite may experience dissolution in the near-surface zone and along the ...
Gypsum | Common Minerals
Anhydrite: When gypsum loses its water component, it forms the mineral anhydrite (CaSO4). When anhydrite absorbs water it becomes gypsum. This ease of exchange is the basis of gypsum's use in plaster. Consequently, the two minerals are very similar to one another and are only easily distinguished by heating a sample in a closed tube.
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