|Land Package:||6,616 hectares|
|Deposit type:||Copper-Zinc Skarn|
|Operation:||Underground mine, room & pillar; flotation plant|
For the fourth quarter and year ending December 31, 2014, the Bolivar Mine produced the following:
|Bolivar||3 Months Ended||12 Months Ended|
|Dec 31, 2014||Dec 31, 2013||Dec 31, 2014||Dec 31, 2013|
|Copper (000 lb)||3,604||3,652||14,946||9,391|
|Zinc (000 lb)||0||0||0||930|
(A detailed summary of production is presented in the Company's Jan 27, 2015 press release.)
MINERAL RESERVES AND RESOURCES
On April 17, 2013, the Company released an updated NI 43-101 compliant reserve and resource estimate for the Bolivar Mine completed by Gustavson Associates LLC of Lakewood, Colorado.
|Proven and Probable
|Measured and Indicated
- The effective date of the mineral reserve and resource estimate is Dec 31, 2012.
- Mineral resources are reported using a 0.66% CuEq cut-off.
- CuEq is based on metal prices of $3.56/lb Cu, $0.96/lb Zn and $26.28/loz Ag and metals recoveries of 82%, 81% and 77% respectively. Gold content was not considered in the CuEq calculation.
- Details of the estimate are provided in the Company's Aug 30, 2012 and Apr 17, 2013 press releases and within a NI 43-101 compliant technical report filed on SEDAR on May 31, 2013.
- Measured, Indicated and Inferred Resources include Proven and Probable Reserves.
- Mineral resources that are not mineral reserves do not have demonstrated economic viability.
(Complete details of the reserve and resource estimate are available in the NI 43-101 technical report - please click here)
Sierra Metals owns 100% of the Bolivar mine located in state of Chihuahua, Mexico, Bolívar is a copper-silver-zinc-gold underground mine using room-and-pillar mining method. The property comprises 12 mining concessions covering approximately 6,616 hectares within the municipality of Urique, in the Piedras Verdes mining district of Chihuahua, Mexico. During 2011, the Company completed the construction of the Piedras Verdes Mill, which is located only 6 kilometres from the Bolivar Mine and had an initial capacity of 1,000 tpd, resulting in a declaration of commercial production in November 2011. The Mill was expanded to 2,000 tpd in November 2013 and at that production rate, the reserves provide a 10 year mine life with an additional year of processing from the stockpile for a total of 11 years.
The Bolívar property is a district-scale property considered prospective for new discoveries of precious metal and bulk-tonnage copper-skarn deposits.
Sierra Metals purchased the claims for the Bolívar Mine between 2003 and 2004, and has conducted mining activities at the Bolívar Mine since February 2005. In 2013, the daily mining rate was approximately 2,000 tonnes per day from the El Gallo Mine. Mined materials are currently transported to Sierra Metals' Piedras Verdes Mill. The mill has a capacity of 2,000 tonnes per day and contains a grinding and two flotation circuits: one for production of copper-silver-gold concentrate and one for production of zinc concentrate. The concentrates are shipped offsite for sale.
The Bolívar property is located in the municipality of Urique, approximately 255 km southwest of Chihuahua, Chihuahua, and roughly 1,250 km northwest of Mexico City. The Project area is situated in the rugged mountainous terrain of the Sierra Madre Occidental, bounded by Copper Canyon, located 50 km north and east of the Bolívar Mine, El Fuerte River, located 18 km south of the Bolívar property, and the villages of Piedras Verdes, 1.5 km north of the Bolívar Mine, and Cieneguita, Chihuahua, located 7.5 km north and west of the Bolívar Mine. The geographic center of the property is located at approximately 27° 05' N Latitude and 107° 59' W Longitude.
Access to the Bolívar Mine is located approximately 397 km from Chihuahua City, consisting of 325 km along paved roads and 70 km by all-season gravel roads to Piedras Verdes village, then 2 km south to the Bolívar Mine.
Sierra Metals obtains electricity from the Mexico main grid system with back-up generators at the Bolívar Mine operations. The villages of Piedras Verdes and Cieneguita are located close to the Bolívar mineral concessions, with a combined population of approximately 1,000 people (approximately 750 for Cieneguita and 250 for Piedras Verdes), including some of the mine employees. Company vehicles provide transportation to the Bolívar Mine.
Industrial water is obtained from the Piedras Verdes Dam, a reservoir that is owned and operated by Sierra Metals. The reservoir drains to El Fuerte River, located approximately 2 km south of the Bolívar Mine. According to Sierra Metals, water from the Piedras Verdes Dam is sufficient to supply mine operations, exploration, and mill requirements. Potable water is available from local sources and is sufficient for mining operations.
Small scale mining was conducted in the Piedras Verdes district during the Spanish Colonial days, but historical records of production were not maintained and production values are unknown.
An estimated 300,000 tonnes of mineralized material was reportedly mined from 1998 to 2000, while the Bolívar Mine was under the control of Bencomo Family, but production records for this period are not available.
GEOLOGY AND MINERALIZATION
The Bolivar Property is situated within the Piedras Verdes Mining District, which is within the major north-northwest trending Sierra Madre Precious Metals Belt extending across the states of Chihuahua, Durango and Sonora in northwestern Mexico. Late Cretaceous – Early Cenozoic sedimentary and volcanic rocks underlie the district (Lower Volcanic Series or "LVS").
In the Bolivar area the LVS is reported to be approximately 750 m thick. The rocks of the LVS are overlain by younger continental rhyolitic and dacitic ignimbrites (up to 1.5 km thick) of the Upper Volcanic Suite ("UVS"), which are interpreted to be Middle Tertiary in age. In general, rocks in the area trend northwest and dip gently to the northeast. These rocks are also cut by several northwest and northeast-trending faults.
Skarn-type Cu-Zn-Ag-Au mineralization in the Bolivar area is structurally controlled and forms mineralized zones that are close to structures. Mineralized zones occupy pre-existing fault structures and extensional openings formed during mineralization. The mineralized zones are dominated by calc-silicate minerals and variable quantities of quartz, calcite, and chlorite. Sphalerite and chalcopyrite are the predominant sulphides, commonly ranging from 5% to 30% (combined), with occasional massive sulphide zones. Sulphides occur within the carbonate rocks, which they replace, a common feature in skarn-type mineralization.
The El Gallo ore body consists of two sub-deposits, "El Gallo Superior" (Upper) and "El Gallo" (Lower). Currently the Superior deposit is being mined by the room and pillar method using ramps. Current mining has shown that the hanging wall and foot wall consist of competent and strong formations. The Inferior deposit, which at this time has not been mined, will require a modified room and pillar method of mining to accommodate the physical characteristics of the deposit.
The dip of the Inferior deposit requires that access to the room and pillar stoping areas be achieved by excavations at a maximum ramp inclination of 13%, which will allow rubber-tired equipment to operate.
The Piedras Verdes mill was built in 2011 with an original capacity of 1,000 tpd which was increased to 2,000 tpd in October 2013. The mill uses the flotation process to produce a copper and a silver concentrate. The mill is expanding the processing plant to process ±2,500 mtpd of ore in 2015.
The current calculated resources and reserves at Bolivar represent a portion of the known mineralized horizons of the Upper and Lower skarns. Exploration efforts will continue to focus on upgrading resources to reserves and expanding known mineralization in the vicinity of the El Gallo area, namely Mina de Hierro, Falla Nathalie and El Salto. As well, exploration drilling is currently underway at several high-value targets such as Lilly Norte, a large breccia pipe with disseminated copper mineralization and at La Sidra, a large gold-silver quartz vein system.
At Bolivar, Sierra Metals is focused on completing the expansion of the Piedras Verdes plant to 2,500 tpd from the actual 2,000 tpd in the second half of 2015.
Currently, the plant uses for power source a combination of electrical power from the national grid and from a diesel generator. In early 2015, the Company expects to be fully connected to the national grid.
1For the three month period ending September 30, 2014