Qualitative determination of the mineralogical composition of sandstone in Amasiri Stone Quarry was performed using X-ray powder diffraction. The d-spacing’s and relative intensities of the x-ray diffraction patterns of the composite sample was compared with the reference diffractogram from mineralogy database. The mineral odinite was identified to be present in the sandstone. The prominent d-spacing’s are 7.18000 (100%), 3.58000(100%) and 1.488000(100%). Odinite is a monoclinic-domatic mineral containing aluminium, hydrogen, iron, magenesium, manganese, oxygen, silicon, and titanium. The chemical formula is (Fe3+, Mg, Al, Fe2+, Ti, Mn)2.5(Si, Al)2O5(OH)4. Cell Dimensions: a = 5.373, b = 9.326, c = 7.363, Z = 2; beta = 104° V = 357.99 Den (Calc)= 2.79. The identification of odinite mineral can be of economic importance because they have been widely used as a foundry-sand bond in the steelmaking industry as well as a binding agent in the manufacturing of iron ore pellets. They are also used to produce earthenware, stoneware and porcelain.