Kyanite is a silicate of aluminium crystallising in the triclinic system. Crystals are usually long and bladed. Its hardness varies from 4 to 5. Its hardness is 7. Specific gravity of kyanite varies from 3.56 to 3.67. Its colour is blue, green or grey and the streak is uncoloured. It has a vitreous to pearly lustre. 

    Kyanite is mainly used in the manufacture of refractory bricks.

    In India, large deposits of high grade, non-transparent massive Kyanite occurs in Lapsaburu, Bihar.

     Talc is a hydrous magnesium silicate. It usually occurs in foliated and compact masses. Crystals are rare. It is a soft mineral, white, grey or green in colour with a pearly to greasy lustre. It is soapy to touch. Its hardness varies from 1 to 1.5 and the specific gravity is 2.7.

      Talc has a variety of uses. It is used in the manufacture of paints, rubber, ceramics, insecticide, toilet powder, etc.

    Serpentine is a hydrous magnesium silicate and may contain iron or nickel or both. Colour of serpentine varies from white to black and various shades of green. Its streak is white. Hardness varies from 2.5 to 4 and the specific gravity ranges from 2.5 to 2.7. Its lustre is greasy or waxy.

   Serpentine is used as an ornamental stone. Fibrous serpentine is chiefly used in insulation and as a fire proofing material.