Chemical composition: CuFeS2, small amount of Ag, Au and Zn may be present in the lattice.
(i) Form: Crystalline and massive aggregates.
(ii) Colour: Brass-yellow
(iii) Lustre: Metallic.
(iv) Streak: Greenish black.
(v) Hardness: 3-4.
(vi) Cleavage: Imperfect.
(vii) Fracture: Conchoidal to uneven.
(viii) Specific gravity: 4.1 – 4.3.
(ix) Diaphaneity: Opaque.
Use: Chief ore of copper.
Chemical composition: CaS04-2H20;. Minor amounts of Fe, Mn, Cr may be present.
(i) Form: Crystalline, laminated, granular, fibrous (Satin spar) and fine-grained massive (Alabaster).
(ii) Colour: Colourless (Selenite), white, gray, various shades of yellow, red, brown.
(iii) Lustre: Vitreous, pearly and silky.
(iv) Streak: White.
(v) Hardness: 2 can be scratched by finger nail.
(vi) Cleavage: Perfect one set.
(vii) Fracture: Conchoidal.
(viii) Specific gravity: 2.32.
(ix) Diaphaneity: Transparent to translucent, (ix) Tenacity: Sectile
Production of plaster of Paris and making of adamant plaster for interior use. Gypsum serves as a soil conditioner and land plaster for fertilizer. Uncalcined gypsum is used as a retarder in Portland cement. Satin spar and alabaster are cut and polished for ornamental purposes. It is also used in manufacture of gypsum plate used in petrological microscopes.