Provided is a pyrogenically prepared SiO2 powder in the form of aggregated primary particles having a statistical thickness surface area (STSA) of 10-500 m2/g, a thickening action based on the STSA of 4-8 mPas·g/m2, and a micropore volume of 0.03-0.07 cm3/g, and a process for preparing the pyrogenic SiO2 powder, which involves: introducing hydrolyzable silicon compounds, a primary gas comprising oxygen, and a primary combustion gas into a mixing chamber to produce a mixture; igniting the mixture in a burner to produce a flame, which is burned into a reaction chamber to produce the pyrogenic SiO2 powder and gaseous substances; and separating the pyrogenic SiO2 powder from the gaseous substances, wherein a ratio of the amount of primary combustion gas introduced to a stoichiometric amount of primary combustion gas required is referred to as gammaprimary and has a value of less than 1, and wherein a ratio of the amount of primary gas comprising oxygen introduced to a stoichiometric amount of primary gas comprising oxygen required is referred to as lambdaprimary and has a value of greater than 1.