Napa soil is natural material that is used by West Sumatra people as medicine of stomachache and diarrhea. Napa soil highly contains SiO2 and Al2O3, the presentation is SiO2 63.20 % and Al2O3 16.55%. Thus, napa soil can be used as alternative material as source of silica and it is hoped that it can be used as potential inorganic m aterial as adsorbent, catalyst and additional material in cement industry. In West Sumatera, there are several areas that lies napa soil, they are district of 50 Kota, district of Tanah Datar, district of Pesisir Selatan, and district of Solok. From the calculation of the Langmuir isotherm equation obtained maximum absorption capacity of the soil Napa adsorbent for Cr (III) ion is 3.28 mg per gram of adsorbent. The Napa soil optimum conditions as adsorbent is at pH 5, the optimum concentration of 250 mg / L, particle size 850 µm and temperature of heating 125°C, and the optimum flow rate of 20 drops / min and the adsorbent at with absorption efficiency of 99.89%.