Field Trip: Climax Porphyry Molybdenum Deposit

Stegen or 520-887-7262
Richard Smith
Reese Ganster

Fee: By March 1, 2006. $100 Member, $185 Nonmember, $50 Student

The Climax mine was for many years the single largest producer of molybdenum.  Since 1918, approximately 470 million tons of ore was mined by underground and open pit methods that produced about 1.9 billion pounds of molybdenum metal.  The Phelps Dodge 2004 Annual Report lists the reserves for Climax as 156 million tons grading 0.19% Mo that would be mined from an open pit.  In addition, 87 million tons at an average grade of 0.25% Mo are classified as mineralized material that could be mined from underground methods should market conditions warrant.

Climax-type porphyry molybdenum deposits are named for the Climax mine.  The Climax orebody formed in several mineralized episodes associated with successive intrusions of high silica, granite porphyry.  There are two separate ore shells, the Upper and Lower orebodies, and the erosional remnants of a third, the Ceresco deposit, that are centered on the apex of plug-shaped intrusions.  The orebodies are stockworks containing complex networks of molybenite bearing veinlets. 

The tour will provide a unique opportunity to examine each of the oreshells and their associated intrusive rocks of this world-class deposit by inspection of key core holes through the deposit.  If the weather and low snow accumulations allow, outcrops in the pit and caved area will be viewed.  The core examination and surface tour will be supplemented by cross sections and surface or underground geological maps.  A key part of the recent Climax work has been the reclamation of tailings and management of the water resources.  These on-going environmental projects, so critical to any historic and current mining operation, will be presented and discussed. 

The field trip will depart from Keystone at 7a.m. and will return in the late afternoon.  A field trip guidebook and lunch will be provided.   We will be at an elevation of 11,300 to 11,700 feet, so each participant will need to be dressed accordingly.  Even though the mine is not actively mining, hard hats, safety glasses, and safety boots are required.  Each person will need to supply their own safety equipment.