monoclinic; hardness 1.5–2.0 Mohs; lumps or white powder(s); used in manufacturing portland cement, plaster of paris and artificial marble [KIR78] [MER06] [STR93]
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Calcium Sulfate Dihydrate is obtained from gypsum, a naturally occurring compound. Also used in the preparation of calcium sulfate and calcium sulfoaluminate.
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A mineral that consists of calcium sulfate with water molecules attached, or the rock that consists primarily of this mineral.
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Nasal symptoms.
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Selenite, which is a salt of selenic acid (H2SeO3), and
very similar to sulphite, is made by the oxidation of
selenium by nitric acid. The low solubility of ironselenite
complexes is responsible for the non-toxic level
of selenium in plants growing on acid soils having a very
high total selenium content. Plants absorb selenite, but
generally to a lesser extent, than selenate, which is
another form of selenium.
Safety Profile
Human systemic effects
by inhalation: fibrosing alveolitis ('growth of
fibrous tissue in the lung), unspecified
respiratory system effects, and unspecified
effects on the nose. Questionable
carcinogen with experimental carcinogenic
data. Long considered a nuisance dust
(dependmg on silica content). When heated
to decomposition it emits toxic fumes of
SO,. See also CALCIUM SULFATE,
CALCIUM COMPOUNDS, and
SULFATES.
Purification Methods
It loses only part of its H2O at 100-150o (see below). It is soluble in H2O and very slowly soluble in glycerol. It is insoluble in most organic solvents.
