Morphology: subspherical, 12-20 mm in diameter, external surface is bluish green to olive green in colour, showing blunt short projections. Internally it is buff in colour.
Active constituents: 50-70% pyrogallol tannin: gallotannic acid, gallic acid and ellagic acid.
Uses: Medicinally: astringent, haemostatic used in treatment of hemorrhoids in form of supp. or oint.
Industrially: 1- in manufacture of ink and paints
2- in tanning of leather.
Chemical test: FeCl3 → bluish black colour.