Geology & Geotechnics of Grasberg.

“Geologi dan Geoteknik – Tembaga Terbuka Grasberg” (Buku Seri 1) was produced by PT. Freeport Indonesia in 2013. This hard cover 290-page large format book was prepared by a large team, and presented in Bahasa Indonesia, with limited availability from PT. Freeport and MGEI.

The main chapter headings are 1) Introduction, 2) the role of the mine geologist, 3) geotechnical and hydrology aspects, 4) the transition from open pit to underground mining, 5) management of the geoscience open pit data base, 6) photo gallery. A positive feature of this book is the accompanying 81 photos, 117 figures, 18 tables and 6 graphs.

The contents start out with a short introduction to the conceptual geological ore emplacement of Grasberg. The role of mine geologist (about 90 pages) is very much a practical site guide to the wide range of mine geological works. This includes some detail, such as the local rock logging sheets along with pictures of key rock types, metallurgical test work, ore controls, drill programs, pit wall design, dump sites and much more. The geotechnical and hydrology chapter (about 80 pages) starts out with the geotechnical domaining the pit and the calculations required to design a safe pit and dump. It continues with pit and dump stability monitoring etc. The hydrology section starts with basic theory, and continues with its application to Grasberg. The smaller section on transition to underground mining is a view into the learning phase of underground mining, including some geotechnical & mine operational issues encountered and overcome. The database management system includes a view into the laboratory Qa/Qc programs, geochemical data, images of core logs, the link between production drilling & mine geology, and much more.

Now that the Grasberg pit has ended, this book is a valuable technical record of Indonesia’s most significant copper & gold mine that future generations of geoscience students can learn from. We must thank these pioneering site geologist, miners, hydrologists and others for undertaking such operational work, and for the considerable effort to produce this book. We must also thank PT. Freeport Indonesia for supporting the development and publishing of this book. It is herein hoped that other mines can follow this lead to record the technology and effort of Indonesia’s exploration, mining and smelting industries.