NOVELTY - Preparing high purity silicon dioxide comprises: (a) preparing a sample of an acidifying agent or acidifying agent and water, with a pH of less than 2, preferably less than 0.5; (b) preparing a silicate solution with a viscosity of 2-10000 poise; (c) adding the silicate solution to the sample, such that the pH of the resulting precipitating suspension is maintained to less than 2, preferably less than 0.5 at any time; (d) separating and washing the resulting silicon dioxide, where the wash medium has a pH of less than 2, preferably less than 0.5; and (e) drying the resulting silicon dioxide.    USE - The silicon dioxide is useful: in the production of elementary silicon or as a high purity raw material for the production of high purity quartz glass for optical wave guide or glass equipment in laboratories and electronics; as a catalyst carrier or as a starting material for the production of high purity silica sols for polishing the discs of high purity silicon (waver); for the production of glass blanks e.g. boules; for the production of glass molded bodies, e.g. pipe systems, over cladding tubes or core rods; as inner cladding materials in optical wave guides; for the production of core materials in planar waveguides; for the production of crucibles; for the production of optical lenses, prisms and photo masks; for the production of diffraction gratings, electrical-, thermal- and magnetic insulators; for the production of containers and instruments for chemical-, pharmaceutical-, semiconductor- and solar industry; for the production of glass rods and glass tubes; for coating of metals, plastics, ceramics or glass; as fillers in metals, glass, polymers, elastomers and lacquers; as a polishing agent for semiconductor materials and electric circuits; in the production of lamps; and as a carrier material for the production of solar cells (all claimed).    ADVANTAGE - The silicon dioxide obtained by the method is of high purity.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for silicon dioxide comprising the impurities aluminum (less than 1 ppm), boron (less than 0.1 ppm), calcium ( less than or equal to 0.3 ppm), iron ( less than or equal to 0.6 ppm), nickel ( less than or equal to 0.5 ppm), phosphorus ( less than or equal to 0.1 ppm), titanium ( less than or equal to 1 ppm), zinc ( less than or equal to 0.3 ppm), where the sum of other impurities and sodium and potassium is less than 5 ppm.