Name: Marmato mine.
Location: The mine is located in the Caldas department, in the Middle Cauca gold district, in Colombia.
Mine Owner/s: Gran Colombia Gold announced the spin-off of its Marmato mining assets through a reverse takeover transaction with Bluenose Gold Corp in February 2020. The resulting issuer is named Caldas Gold Corp.
With the transaction completed, Caldas Gold is well capitalised to take the Marmato project forward.
Brief Description: Marmato comprises three separate areas within a historic mining district – Zona Alta (upper zone), Zona Baja (lower zone) and Echandia (the northern portion of the project).
Brief History: The Marmato district has been exploited since precolonial times by the Quimbaya people. The Spanish colonists assumed control of the Marmato mines in 1527 and the area has been in almost continuous production ever since.
The current mine has been in operation since 1991.
Primary Metals/Minerals: Gold.
Secondary Metals/Minerals: Silver.
Geology/Mineralisation: The mineralisation in the current mine comprises three distinct phases. The first phase is characterised by the mesothermal vein/veinlet mineralisation, which defines the Marmato Deeps mine, followed by an epithermal low sulphidation style, superimposed by an epithermal intermediate sulphidation phase.
Gold/silver mineralisation is mainly hosted by a pyrite/sphalerite vein to veinlet system fitting in a sinistral transpressional shearing system, which is associated with intermediate argillic alteration within the host porphyritic rocks. About 92% of the gold-/silver-bearing particles are intergrown with sulphides or occur at sulphide-gangue grain boundaries. Current mining in the area is through narrow underground stoping of the higher-grade vein mineralisation.
Reserves: Not stated.
Resources: Total measured resources as at July 31, 2019, were estimated at 2.1-million tonnes grading 4.9 g/t gold. Indicated resources are estimated at 15.2-million tonnes grading 3.5 g/t. Inferred mineral resources are estimated at 44.9-million tonnes grading 2.3 g/t gold.
Mining Method: On October 4, 2017, Gran Colombia announced a change in the focus of Marmato’s mining style – from openpit to underground mining, which includes an increase in cutoff grade for the mineral resource estimate and the addition of new material from the deep mineralisation below the existing Mineros Nacionales mine.
Major Infrastructure and Equipment: The Marmato mining assets principally comprise the existing producing underground gold mine (including the right to mine in the lower portion of the Echandia licence area), the existing 1 200 t/d processing plant and the area encompassing the Deeps mineralisation, all located within the Zona Baja mining licence area.
The mine has a mature and functioning infrastructure system, including all the necessary facilities and supporting utilities to produce at the planned production levels. The current facilities include a security checkpoint that provides access to the office and administrative office area.
The facilities include employee motorcycle parking, a meeting area, a cafeteria, multiple shops and warehouses, a camp with cafeteria, an exercise and sports field, equipment storage yards, a compressor station, a welding shop, a 500 kW back-up generator, a processing plant, an underground mine, explosives storage a short distance from the mine that is managed by the military, a main power substation and distribution powerlines with motor control centres at key loads. The site is considering additional water supply from the Cauca River to supplement water availability during the dry season.
Prospects: The preliminary economic assessment completed on the mine in 2019 charts a path for expansion of mining operations at Marmato, ultimately comprising two distinct operations – the existing Upper Zone operation and a new Deeps Zone operation that is situated directly below the Upper Zone vein system.
Caldas aims to develop the Deeps Zone mineralisation, build a new 4 000 t/d processing plant and new dry stack tailings storage facilities. Mechanised mining using an underground longhole stoping method is expected to start in 2023, with an additional estimated 1.6-million ounces of gold recovered over a 16-year mine life.
Contact Details:
Caldas Gold
Tel +1 416 360 4653
Email investorrelations@caldasgold.ca
Website https://www.caldasgold.ca