Petra Strunk: 1, 3; Anke Bracht: lead picture, 2, 4 Petra Strunk: 1, 3; Anke Bracht: lead picture, 2, 4 TEXT Dr. Petra Strunk, AT Mineral Processing, Anke Bracht M.A., ZKG International
Petra Strunk: 1, 3; Anke Bracht: lead picture, 2, 4
