P-wave velocity measurements on spherical sample (Pconf ≤ 200 MPa; T = 20¿C) and P- and S-wave velocity measurements on cube (Pconf ≤ 612 MPa; T ≤ 600¿C) were carried out. It will be demonstrated that combination of both these data sets increases the accuracy in the determination of the elastic moduli of a sample. The elastic moduli can be calculated to maximum confining pressure, although the data for Pconf > 200 MPa are restricted to three orthogonal directions. Even extrapolation of the data beyond the measuring range appears to be possible, if reliability of the relation used for extrapolation can be ensured.