A seal for a sensor element of a gas sensor is known, for example, from German Published Patent Application No. 195 32 090 A1, in which the sensor is mounted into a longitudinal bore of a housing by way of at least two sealing members and a deformable auxiliary seal arranged between the sealing members. The two sealing members are made of magnesium aluminum silicate (steatite), and the sealing member mounted between those sealing members is made of the hexagonal allotrope of boron nitride.