Name: Bolañitos mine.

Location: The mine is located in the state of Guanajuato, in Mexico.

Holding and Controlling Company: Endeavour Silver (EDR).

Brief Description: The Bolañitos mine is Endeavour Silver’s second and most profitable mine, situated on 2 500 ha in the second-largest historic silver mining district in Mexico.

The mine comprises three operating mines – Bolañitos, Lucero and Asunción – which are located near the town of La Luz, about 12 km to the north-east of Guanajuato. The Bolañitos mine and the 1 600 t/d processing plant are situated about 5 km west of Cebada. All of the mines are readily accessed by paved and gravel roads. EDR also owns the inactive Cebada mine, located about 5 km north of the city of Guanajuato, and the inactive Golondrinas mine, which is 3.5 km to the south-west of Cebada.

Brief History: In 1968, Fresnillo Company acquired claims and incorporated Negociación Minera Santa Lucía (now Cebada) and the Peregrina mine. A photogeological study in the area of the Cebada mine holdings was completed in 1973.

Production began at the Cebada mine in 1976. The mine produced 1.28-million tonnes between 1976 and 1995.

In 2003, Grupo Guanajuato closed the Torres, Sirena, Peregrina and Apolo mines. The Bolañitos, Golondrinas, Asunción and Cebada mines stayed in production on a break‐even basis.

EDR acquired the Bolañitos project – which included, Mina Cebada, Mina Bolañitos, Mina Golondrinas and Mina Asunción, as well as a few other currently closed mines – from Peñoles, the owner at the time, and Minas de la Luz, the operator at the time, in 2007. Minas de la Luz was kept on as the operator of the mines until June 2007, when EDR assumed control.

Products: Silver and gold.

Geology/Mineralisation: The Bolañitos mine is located in eastern part of the Guanajuato mining district, in the south-eastern portion of the Sierra de Guanajuato, which is an anticlinal structure about 100 km long and 20 km wide. Bolañitos is located on the north-east side of this structure where typical primary bedding textures dip 10° to 20° to the north‐north-east.

Economic mineralisation at Bolañitos is known to extend as much as 250 m vertically from 2 300 m to 2 050 m elevation, except for the La Luz vein that extends 400 m vertically from 2 300 m to 1 900 m.

The Guanajuato mining district is characterised by classic, high-grade silver/gold, epithermal vein deposits with low sulphidation mineralisation and adularia‐sericite alteration. Veins in the Guanajuato district are typical of most epithermal silver/gold vein deposits in Mexico with respect to the volcanic or sedimentary host rocks and the paragenesis and tenor of mineralisation.

The Guanajuato mining district hosts three major mineralised fault systems – La Luz, Veta Madre and Sierra.

Of the geological formations associated with the Guanajuato district, only the Esperanza and La Luz formations occur in the Bolañitos mine area with mineralisation residing primarily within the La Luz formation. Mineralisation is known to dissipate at the contact with the Esperanza formation.

The Veta Madre was historically the most productive vein in the Guanajuato district, and is by far the most continuous, having been traced on the surface for nearly 25 km. The vein dips from 35° to 55º to the south-west, with measured displacement of about 1 200 m near the Las Torres mine and 1 700 m near the La Valenciana mine. The most productive veins at Bolañitos strike parallel to the Veta Madre system.

Bolañitos mineralisation is directly related to faulting. Mineralisation occurs as open‐space fillings in fracture zones or impregnations in locally porous wall rock. Veins that formed in relatively open spaces are the main targets for mining.

Mineralised veins at Bolañitos consist of the classic banded and brecciated epithermal variety. Silver occurs primarily in dark sulphide‐rich bands within the veins, with little mineralisation within the wall rocks. The major metallic minerals reported include pyrite, argentite, electrum and ruby silver, as well as some galena and sphalerite, generally deeper in the veins. Mineralisation is generally associated with phyllic (sericite) and silicification alteration, which forms haloes around the mineralising structures. The vein textures are attributed to the brittle fracturing‐healing cycle of the fault‐hosted veins during and/or after faulting.

Economic concentrations of precious metals are present in “shoots” distributed vertically and laterally between nonmineralised segments of the veins. Overall, the style of mineralisation is pinch‐and‐swell, with some flexures resulting in closures and others generating wide sigmoidal breccia zones.

Reserves: Total proven reserves as at December 31, 2016, were estimated at 157 000 t grading 90 g/t silver and 2.84 g/t gold. Probable reserves were estimated at 238 000 t grading 104 g/t silver and 1.81 g/t gold.

Resources: Total measured resources as at December 31, 2016, were estimated at 89 000 t grading 150 g/t silver and 2.29 g/t gold. Indicated resources were estimated at 698 000 t grading 162 g/t silver and 2.04 g/t gold. Inferred resources were 1.15-million tonnes grading 153 g/t silver and 2.29 g/t gold.

Mining Method: Conventional drill-and-blast methods are used to extract the ore at Bolañitos, with ramps and adits providing access to the mining areas.

Major Infrastructure and Equipment: The mine has its own fleet of scoops, trucks, and drills. Ore is typically delivered to the surface by contactors using truck haulage up the ramps.

The processing plant has a capacity of 1 600 t/d following an expansion project in 2012, which added 6 × 16 vibration screens, four additional flotation cells of about 14 m³ each, six first cleaner cells of about 2.9 m³ each, six second cleaner cells of 1.42 m³ each, conveyor belts and a flocculent mixing system.

Prospects: Endeavour plans to optimise throughput at Bolañitos and regain access to reserves at the mine.

Contact: Investor relations, Meghan Brown.

Contact Details:
Endeavour Silver Corp
Tel +1 604 685 9775 
Fax +1 604 685 9744
Email info@edrsilver.com
Website http://edrsilver.com