Лаборатория иши №5

Ng = l, 5305;
Np = l, 5207.
The angle between the optical axes is 2V = 58 °. Gypsum crystals are colorless and transparent, but when mixed, they have a variety of gray, yellowish, reddish hues. A small amount of evenly distributed compounds in gypsum does not adversely affect the quality of the binder formed from gypsum.
The density of gypsum depends on the mixtures in it and is 2200-2400 kg / m3. The volumetric mass of gypsum gravel is 1300-1600 kg / m3, the humidity varies sharply in the range of 3-5% and more. Hardness of gypsum on Moss scale 2.
Water solubility of gypsum (due to calcium sulfate)18 ° Cat a temperature of 0.2%,40 ° Cat a temperature of 0.21 and100 ° Cyes - 0.17%. Needless to say, the temperature32 ° Cand41 ° CThe solubility of gypsum is highest in the range of According to various researchers, the water solubility of gypsum varies. The water solubility of gypsum depends on the ability of gypsum to form highly saturated solutions, as well as the size of its crystals. According to Gullet,25 ° CThe solubility of gypsum in calcium oxide reaches 2.08 g / 1 for crystals of size 2 μm, while the solubility is 2.47 g / 1 for crystals larger than 0.3 μm. If calcium oxide hydrate is involved, the solubility of calcium sulfate decreases. The solubility of gypsum in dilute hydrochloric acid and nitric acids, as well as in some saline solutions, is higher than in water.
The thermal conductivity of gypsum is low, 1.6-46 ° Cat a temperature of 0.3 W / (m K). The crystal lattice of anhydride consists of four molecular elemental cells each, and due to their dense arrangement, calcium sulfate is much stronger than the crystal lattice of other species.
Unlike two-molecule aqueous gypsum, anhydride has the ability to bind strongly in three directions in a mutually perpendicular position. Anhydride crystals are mainly small, the surface separating them is carved with rough lines. Refractive indices of anhydride:
Ng = 1,614;
Np = l, 57
Pure anhydrite is white and, depending on its composition, has a different color, like gypsum. Anhydride is a much denser and stronger rock than the two-molecule aqueous gypsum. Its density is 2900-3100 kg / m3.