We propose to carry out an elastic neutron scattering experiment at the High Magnetic Field Facility for Neutron Scattering of the Helmholtz-Zentrum Berlin on the natural mineral atacamite in applied magnetic fields up to 25 T and temperatures down to 1.5K (4He cryostat). Atacamite, with chemical formula Cu2Cl(OH)3, exhibits a magnetic behavior which is characteristic of a frustrated quantum magnet and further, band structure calculations suggested that the system can essentially be understood in terms of a quantum sawtooth chain. Depending on the ratio of the coupling constants there is a 1/2-magnetization plateau predicted by theory, and which we observed recently in magnetization measurements up to 50 T. We wish to study the plateau phase above 21 T for H || c axis by means of elastic neutron scattering.