English Name

Selenite (CaSO4. 2H2O)

Definition

Godanti is Selenite (CaSO4, 2H2O) mineral.

Synonyms

Samskrta : Godanta

Regional Name

English - Selenite, Gypsum Gujarati - Godantī, Ghāpa´a, Chirodī Hindi - Godanti Marathi - Godantī, Śiragola Tamil - Karpura Chilajattu (S.F.I.) Telugu - Hara sothamu Urdu - Godanti (N.F.U.M.)

Broad Classification

Hydrous calcium sulphate

Origin and occurrence:

Godanti occurs as evaporates; extensive sedimentary deposits interbedded with limestone, red shales and clay stones etc. It occurs generally in pure mineral form. In India, significant occurrences of Godanti are at Nellore, Prakasam and Guntur in Andhra Pradesh and Bikaner, Barmer, Jaisalmer, Nagaur, Ganganagar and Pali in Rajasthan. Major production of Godanti comes from these two states only. There are some other occurrences also reported in the states of Gujarat, Jammu and Kashmir, Himachal Pradesh, Uttar Pradesh and Tamil Nadu.

Physical Properties

Nature : Crystalline showing elongated tabular crystals Colour : Greyish white Streak : White Cleavage : Perfect Fracture : Even Lustre : Silky Tenacity : Sectile Transparency : Translucent Hardness : 2 Sp. Gr. : 2 to 2.5

Optical properties

Anisotropic, biaxial positive, large 2V, weak birefringence. Refractive index : ηα,1.520; ηβ,1.524; ηγ, 1.530 (Appendix–2).

Chemical Properties:

Test for sulphate radical: Take about 0.5 g powdered sample in a test tube. Add 10-15 ml dilute hydrochloric acid and boil. Add 10 % barium chloride solution drop wise. The resulting solution gives white precipitate of barium sulphate. Assay: Should contain not less than 20% Calcium (Ca) or 30% calcium oxide (CaO) when analysed by gravimetric method (Appendix-3.1.5). Heavy metals and Arsenic: Should not contain more than the stated limits for the following: Lead = 6 ppm, Arsenic = 1 ppm and Cadmium = 4 ppm (Appendix-3.2).

Śodhana

Shall not be used in formulations without subjecting it to śodhana. Godantī is used in the form of bhasma, the details of which are given in the monograph of bhasma.