Apex Silver's wholly owned San Cristobal property is considered to be the world's largest
primary silver mine development project. It is also one of the largest zinc mining projects
in development today.
Apex Silver’s 65%-owned (Sumitomo Corporation - 35%) San Cristobal property is considered to
be one of the world’s largest silver-zinc-lead development projects.
San Cristobal is located in the Potosi district of southwestern Bolivia and hosts approximately
470 million ounces of silver and 8 billion pounds of zinc and 3 billion pounds of lead contained
in 231 million tonnes of open-pittable proven and probable reserves. As the orebody is open both
at depth and laterally, reserve expansion potential is considered excellent.
The San Cristobal deposit occupies the central portion of a depression associated with volcanism.
The four-kilometer diameter depression is filled with fine to coarse-grained volcanoclastic sedimentary
rocks. Disseminated and stockwork silver-lead-zinc mineralization formed locally both within the
volcanoclastic sediments and in the intrusions themselves.
Initially, the two largest areas of mineralization, the Jayula and Tesorera deposits, were drilled
separately. Subsequent drilling resulted in a nearly two-fold increase in reserves as it was discovered
that the Jayula and Tesotera deposits were one large and continuous deposit, now called the San Cristobal
The company commenced development and construction of San Cristobal following Board approval received
in December 2004.
Construction of a power line from the town of Punutuma to San Cristobal has been completed and began
drawing power from the national power grid during November 2006. During 2006 began mining ore began
at the San Cristobal project and as of December 31, 2006 approximately stockpiled 6.5 million tonnes
of work-in-process ore.
Approximately 1.3 million tonnes of the total stockpiled ore are sulfide ore
and the remainder is oxide ore. The sulfide ores will be processed through the San Cristobal mill first
with the oxide ores scheduled for processing later in the mine life.
A long-term agreement is in place for the transportation of the concentrates by rail to the port
in Mejillones, Chile. Construction of the rail spur from the mine site to the main rail line began
during the third quarter of 2006. It is expected to be completed during the second quarter of 2007.
Concentrates will be unloaded from the rail cars at a facility at the port in Mejillones and then
loaded into ships for export. Once the concentrates have arrived in Mejillones, they will be shipped
by bulk carriers to smelters around the world.
The ore’s primary lead material is silver-rich galena (lead sulfide) and the primary zinc material
is sphalerite (zinc sulfide). San Cristóbal will mainly produce two products: a zinc/silver
concentrate and a lead/silver concentrate. Silver’s end uses are in photographic paper and film,
electronics and jewelry/tableware, batteries, brazing alloys, solder, mirrors, medicines, dental
fillings, ammunition, medals, and coins. Zinc is used in steel galvanizing and lead in acid batteries.