We have assembled a team of accomplished and successful experts in the mining industry who are committed to achieving the goals of the company and successfully developing the communities in which the company has mining operations.

  • Mike Bunch – Executive Vice President/Chief Operating Officer
  • M. Craig Patrick - Executive Vice President/ Chief Administrative Officer
  • David Tretbar - Vice President of Exploration and Mineral Resources
  • Takashi Nakabayashi - Vice President of Business Development/Secretary and Treasurer
Mike Bunch

Mike Bunch

Executive Vice President/Chief Operating Officer

As the Executive Vice President and Chief Operating Officer (COO), Mike Bunch reports to the President & Chief Executive Officer and is responsible for the company's optimization of day-to-day operating activities, including safe production; expense, cost and margin control; and financial, legal, quality, and environmental management. He directs the short-term and long-range planning and budget development to support strategic business goals and is responsible for execution of operating policies to support overall company goals and objectives.

Career Profile

Mike Bunch is a registered professional mining engineer (Arizona) with more than 25 years of domestic and international mining & mineral process experience including the successful development and startup of a world class copper mine (El Abra, Chile) and a world class lead-zinc-silver mine (San Cristobal, Bolivia).

Prior to joining Summit Mining International in October 2009, Mr. Bunch was Vice President and General Manager of the San Cristobal Mine where he implemented a business management system that moved the project from bankruptcy to profitability in less than a year. San Cristobal became the first mine in the world to achieve simultaneous triple international certification (ISO 9001, ISO 14001, & OHSAS 18001).

Mr. Bunch's professional experience includes senior management positions with both Cyprus Amax and Phelps Dodge at El Abra, Chile (1995), Sierrita, Arizona (1998), Bagdad, Arizona (2000), and La Candelaria, Chile (2003).

From 1989 to 1994, he held multiple operating, maintenance, engineering and project development roles with Cyprus Amax (Sierrita and Twin Buttes, Arizona).

He began his mining career in 1978 at Newmont's underground Magma Mine (San Manuel) where he supervised both operations and development areas including draw and haulage, concrete, timber repair, drifts and raise stations, grizzly drifts, raises, and undercuts.


  • Bachelors of Science Mining Engineering, University of Arizona, 1978
  • Masters of Business Administration, University of Phoenix, 1992
  • Registered Professional Mining Engineer, State of Arizona License #47663, 2008
M. Craig Patrick

M. Craig Patrick

Executive Vice President/ Chief Administrative Officer

As the Executive Vice President, Chief Administration Officer of Summit Mining International, Craig Patrick is responsible for executing organizational strategies, programs and processes designed to support strategic goals and operational objectives for corporate and international administration functions. The responsibilities include the overall management of employment and related legal compliance, compensation, and executive support functions.

Mr. Patrick is responsible for the overall development of systems, structures, policies and programs to meet organizational needs in addition to providing human resources guidance and technical assistance to other functional areas. Mr. Patrick also has responsibility for management of the international assignment and expatriate programs, including tax equalization, and relocation, worldwide compensation and benefits.

Career Profile

Profile Mr. Patrick is a senior executive with more than 40 years of international experience in the mining industry that began as a laborer in an open pit copper/molybdenum operation. His background includes surface/underground operations, crushing /conveying, ore processing, smelting/refining, SXEW, and molybdenum roasting/cannery facilities.

Mr. Patrick’s commodities experience includes coal, copper, lithium, gold, lead, zinc, rhenium, platinum, palladium, iron, silver, and molybdenum. Prior to joining Summit Mining International in 2009, Mr. Patrick held a number of senior level positions, including Vice President Organizational Development for Apex Silver, Vice President, Corporate Development for Golden Phoenix; a mid-tier diversified metals mining company and continued to serve as an advisor to their Board of Directors. From 2005 through mid-2007, Mr. Patrick was an internal consultant in resource management for Phelps Dodge, where he was involved in the development of a Life Cycle System to be implemented throughout the organization and the structuring of an internal reclamation and construction company.

Mr. Patrick has also held the position of Vice President, Organizational Effectiveness for Kennecott Energy (Rio Tinto), where his primary emphasis was on reorganization and growth of the company through acquisition and merger; Director, Operational Excellence and safety for ASARCO, Inc., where as a General Electric Acceleration Process Facilitator, he led company-wide teams in continuous improvement initiatives; and Stillwater Mining Company, where he was the Vice President of Human Resources for an 800 employee workforce.

While at Cyprus Minerals from 1986 to 1998, Mr. Patrick held the positions of Regional Director, Organizational Services; Manager, Safety and Human Resources for Latin American Operations, and served as Manager of Human Resources and Safety for various operating sites. During that time he was involved in the acquisition of Inspiration Consolidated Copper Company, the start-up of Cerro Verde, Peru, the start-up of El Abra, Chile and a variety of support function initiatives.


  • MBA, 1984
  • B.S.B.A., (Economics), University of Arizona, 1978
David Tretbar

David Tretbar

Vice President, Exploration and Mineral Resources

As the Vice President, Exploration and Mineral Resources of Summit Mining International, David Tretbar is responsible for developing exploration programs, implementing exploration and resource development strategies, and providing technical support in all aspects of mine and mill production. The responsibilities include oversight of the exploration and mine geology programs at Minera San Cristobal in Bolivia, project due diligence for strategic alliances and joint ventures, and executive support functions within Summit Mining and parent company Sumitomo Corporation.

Career Profile

Mr. Tretbar has wide-ranging experience in surface and underground exploration, resource modeling, mine development and production, laboratory operations, mineral analysis, process metallurgy, and project management. Prior to joining Summit Mining International in 2010, Mr. Tretbar held a number of operational management level positions, including Chief Resource Geologist for Apex Silver at Minera San Cristóbal and both Mill Manger and Manager Engineering & Geology for the Ashdown Molybdenum Mine in Nevada.

Mr. Tretbar has worked as an underground mine geologist at several Nevada gold mines, including 4 years at the Getchell Mine where he conducted his Master’s degree research on geochemistry and mineralization of the deposit. He later spent 3 years as process mineralogist for Barrick Gold Corporation at the Goldstrike Operation. From 2004 to 2007 Mr. Tretbar was senior exploration geologist for Alamos Gold at their Mulatos Mine in Sonora, Mexico. While there he designed and directed construction of 2000m of exploration tunnels and managed near-mine exploration programs. At the narrow-vein, high-grade Ashdown Molybdenum Mine in northern Nevada, David simultaneously managed the molybdenum flotation plant and designed the underground ramp access and stope sequence mining plans.


  • B.S. Geology, Northern Arizona University, 1995
  • M.S. Geochemistry, University of Nevada Reno, 2004


  • Certified Professional Geologist – American Institute of Professional Geologists
  • Registered Professional Geologist – Arizona
Takashi Nakabayashi

Takashi Nakabayashi

Vice President of Business Development/Secretary and Treasurer

As the Secretary of Summit Mining International, Takashi is responsible for handling the company’s share transactions, managing internal control issues, compliance issues, managing records retention including document filing and arranging for shareholder’s and directors’ meetings. As the Treasurer of Summit Mining International, Mr. Nakabayashi is responsible for overseeing and directing the financial elements of the company's operations to include approving of payments, cash balance reconciliation, tax filing, salary payroll practice and fixed asset management.

Career Profile

More than 13 years of international business experience. Joined Sumitomo Corporation in 2003 in the Non Ferrous & Raw Material Business Department. From 2003-2005, worked on trading section for Copper, Zinc and Lead Concentrate sales (Cerro Verde, Candelaria, Escondida (Cu Conc) & Red Dog, Tizapa, San Cristobal (Zn /Pb Conc). From 2005 - 2007, worked on investment for the San Cristobal Project (Zinc, Silver and Lead) located in Bolivia. In 2007 was appointed Commercial Manager at Sumitomo Corp. Peru Office, then in 2011 returned to working on the San Cristobal project, first at Sumitomo Corp. in Tokyo, then in 2013 at Minera San Cristobal mine site (CSR&E Department) in Bolivia. As of May 2015 I have been at Summit Mining International in my current position. His specialized field is in Finance and Marketing in the base metals industry.


  • Master of Material Science, Kyushu University