Slate, Scihist and Phyllite

It is a metamorphic rock, formed due to low grade regional metamorphism, composed of finely divided micaceous minerals, including chlorite with subordinate quartz and feldspar. All minerals are flattened and elongated in the cleavages plane. It splits easily along the cleavages plane, sometimes schistosity and gneissic textures are well developed.

Commercially, slates are defined as layered stone that can be split into slices of thickness ranging from 8 to 14 mm. Slates/Scihists are generally fine grained and occur in various shades of grey to steel grey, greenish grey, dark grey, purplish grey, brownish, ash and sometimes with other pleasing colours. Slates/Schists have varying degree of hardness. The harder ones are being sometimes used for flooring. These are low cost decorative stones having wide applications after cutting for use in interior as well as exterior decorations.

Schist and slate stones are argillaceous rocks having different grades of metamorphism. Certain planes of easy split called ‘schistosity’, are developed in these rocks due to metamorphism, which make these rocks suitable for decorative use.

Slate is primarily used for roofing, also called roofing shingles. Slate tiles are often used for interior and exterior flooring, stairs, walkways and wall cladding.