Nano-fibriforin silica was extracted from chrysotile by the acid-leaching method. The acid-leached residue of chrysotile has been studied by TEM, XRD, FTAR, and thermal analysis techniques, etc. When the magnesium leaching degree (MLD) is over 90%, the nano-fibriform silica consists of hydrous silicon dioxide (above 90%) with small amount of magnesium trapped inside the Si-O network. The amount of hydroxyl on surface of nano-fibriform silica is 6 unit nm(-2). This value is between the values of turned and precipitated silica. This study shows that nanofibriform silica is a kind of amorphous matter with a high special surface area (368 m(2)/g), a high adsorption (330 cm(3)/g), and a larger pore volume (0.51 cm(3)/g). The diameter of a single silica fiber is 20-30 rim. The nitrogen adsorption isotherm is similar to Type TV curve. The nano-fibriform silica is one of mesopores materials. (c) 2005 Elsevier Inc. All rights reserved.