A new interesting growth phenomenon for amorphous materials has been discovered for silica fibers prepared by a Sn-assisted vapor-liquid-solid growth method. The fibers exhibit triangular cross sections (see figure) and are surface decorated with SnO2 nanoparticles, forming SiO2/SnO2 heterostructures. They have a typical length of several tens of micrometers (some may even reach a length of over 100 mu m) and a mean diameter of ca. 0.5-2.5 mu m.