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Gypsum is also formed as a by-product of sulfide oxidation, amongst others by pyrite oxidation, when the sulfuric acid generated reacts with calcium carbonate. Its presence indicates oxidizing conditions. Under reducing conditions, the sulfates it contains can be reduced back to sulfide by sulfate-reducing bacteria.
Gypsum occurs on every continent and is the most common of all the sulfate minerals. Gypsum is formed as an evaporative mineral, frequently found in alkaline lake muds, clay beds, evaporated seas, salt flats, salt springs, and caves. It is frequently found in conjunction with other minerals such as, copper ores, sulfur and sulfides, silver ...
At this point, the mineral gypsum begins to form, which is then followed by halite at 10%, [2] excluding carbonate minerals that tend not to be evaporites. The most common marine evaporites are calcite, gypsum and anhydrite, halite, sylvite, carnallite, langbeinite, polyhalite, and kainite.
The process by which this synthetic gypsum is created is also known as forced oxidation: 2 CaSO 3 + H 2 O + O 2 → 2 CaSO 4 ·2H 2 O. A natural alkaline usable to absorb SO 2 is seawater. The SO 2 is absorbed in the water, and when oxygen is added reacts to form sulfate ions SO 2− 4 and free H +.
Phosphogypsum (PG) is the calcium sulfate hydrate formed as a by-product of the production of fertilizer, particularly phosphoric acid, from phosphate rock. It is mainly composed of gypsum (CaSO 4 ·2H 2 O).
In the form of γ-anhydrite (the anhydrous form), it is used as a desiccant. One particular hydrate is better known as plaster of Paris, and another occurs naturally as the mineral gypsum. It has many uses in industry. All forms are white solids that are poorly soluble in water. [5] Calcium sulfate causes permanent hardness in water.
A desert rose is an intricate rose-like formation of crystal clusters of gypsum or baryte, which include abundant sand grains. [1] The "petals" are crystals flattened on the c axis, fanning open in radiating clusters. The rosette crystal habit tends to occur when the crystals form in arid sandy conditions, [1] such as the evaporation of a ...
Gypsum "Firecode C". This board is similar in composition to Type X, except for more glass fibres and a form of the vermiculite used to reduce shrinkage. When exposed to high heat, the gypsum core shrinks, but this additive expands at about the same rate, so the gypsum core is more stable in a fire and remains in place even after the gypsum ...