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Riacho dos Machados mine, Brazil

18th August 2017

By: Thabi Shomolekae

Creamer Media Senior Writer

     

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Name: Riacho dos Machados (RDM) mine.

Location: The mine is located in the north of Minas Gerais, in Brazil.
 
Holding and Controlling Company: Brio Gold.

Brief Description: The mine is a conventional openpit and carbon-in-leach operation.

The property comprises 14 tenements and two mining concessions of about 24 072 ha.

Brief History: Companhia Vale do Rio Doce (CVRD) discovered the Mineração Riacho dos Machados (MRDM) deposit in early 1986. CVRD operated the property as an openpit gold mine until it was closed in 1997.

During the late 1990s, most site facilities were removed or reclaimed after cessation of mining activities, except for the power and water supply systems.

The mine remained inactive from 1997 to October 2008. Carpathian acquired the mineral rights to the mine in 2008 and started with prospecting and exploration.

Carpathian rebuilt the mining and process facilities from 2012 to 2014, with the mining and processing of openpit ores starting in March 2014.

Brio Gold acquired the mine in April 29, 2016.

Products: Gold.

Geology/Mineralisation: The RDM gold deposit occurs in the north-south-trending Araçuaí Fold-Thrust Belt along the eastern margin of the São Francisco Craton, a major Archean-age basement block, which underlies more than one-million square kilometers in eastern Brazil.

The Araçuaí Fold Belt is 15 km to 45 km wide and comprises a series of metavolcanic-metasedimentary rocks of late Archean to late Proterozoic age, which were deposited in a broad intracontinental to oceanic rift-type basin that existed between the São Francisco Craton and the Congo Craton (now part of Africa).

The mineralisation has a typical amphibolite facies mineral association, which is progressively altered to greenschist facies assemblage.

The principal host for the gold mineralisation is the quartz muscovite schist of the RDM Group. The mineralisation occurs in a belt of hydrothermally-altered rock developed along a district-scale shear zone that extends almost 30 km along a N20°E strike direction and dips 40° to 45° east.

Mineralisation occurs in the hydrothermal/shear zone, and gold grades are closely related to the sulphide content, especially arsenopyrite.

Reserves: Total proven and probable reserves as at March 31, 2017, were estimated at 27.39-million tonnes grading 1. g/t gold.

Resources: Total measured and indicated resources as at March 31, 2017, were estimated at 6.12-million tonnes grading 0.95 g/t gold.

Total inferred resources as at March 31, 2017, were estimated at 9.54-million tonnes grading 1.19 g/t gold.

Mining Method: Conventional openpit mining, including drilling, blasting, loading and hauling.

Major Infrastructure and Equipment: The property includes the openpit mine, openpit waste storage facilities and processing facilities.

Electricity at the mine is currently supplied by eight diesel-powered generators.

Brio Gold completed the construction of a water storage dam in the first quarter of 2017, which will allow for a consistent water supply.

Prospects: As a result of a large mineral reserve and resource, and optimisation initiatives, Brio Gold has updated the RDM mine plan. The enhanced mine plan is expected to result in more efficient mining, increased waste and ore productivity and lower operating costs.

The mine life has been extended by three years for a total of nine years and average yearly production over the life-of-mine has increased by 3% when compared with the prior mine plan.

Meanwhile, Brio Gold hopes to commission the new grid-connected power line in the second quarter of 2018, replacing the current lower-capacity diesel power generators. This is expected to reduce costs, improve grid/recovery and expand mill throughput. The connection to low-cost grid power will complete the plant expansion from an operating capacity of 7 000 t/d to 9 000 t/d.

Contact: Brio Gold investor relations

Contact Details:
Brio Gold
Tel +1 416-860-6310
Email info@briogoldinc.com
Website http://briogoldinc.com

Edited by Sheila Barradas
Creamer Media Research Coordinator & Senior Deputy Editor

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