The Topia mine is located near the town of Topia, Durango State, Mexico, approximately 235 kilometres northwest of the city of Durango. The property is accessible by traveling north for approximately 200 km on paved Highway 23, and west for 150 km on a paved and gravel road to Topia. The Topia town is presently served by daily small-aircraft flights from Durango and Culiacan and is the principal centre for the area with schools, shops, a small hospital, and public telephone and internet access.

Topia is a silver-gold-lead-zinc mine consisting of several narrow-vein, underground operations utilizing a modified cut-and-fill mining method known as ‘resuing’. The mines are typically accessed by unpaved mountain roads leading to adits that either follow the veins into the mountains or are driven to cross-cut them. The veins range from 15 to 150 cm wide, with an average of 30 cm. Broken ore is hauled from the mines by eight-tonne truck to the central processing plant on the edge of town.

The plant capacity is approximately  220 tonnes per day average over the year but is being de-bottlenecked to run 270 tonnes per day average and at an instantaneous rate close to 300 tpd on a daily basis. The plant consists of a two-stage crusher which produces a fine ore mill feed (3/4 inch), a grinding circuit consisting of three ball mills, and two conventional flotation circuits producing a high-quality silver- and gold-rich lead concentrate plus a zinc concentrate. The concentrates are transported to the Pacific port of Manzanillo, where they are sold to commodity traders. From Manzanillo, the concentrates are shipped to smelters worldwide for the extraction and refining of metals.

Operating Results

  2018 2019 2020
Tonnes ore milled (000's) 74 79 57
Ore silver grade (g/t) 344 392 352
Plant silver recovery (%) 93.4 93.9 92.0
Metal production, (000's Ag Eq oz)1 1,548 1,785 1,086
Silver production, (000's oz) 761 939 597
Gold production (oz) 1,087 1,344 835
Lead production (tonnes) 1,958 1,960 1,233
Zinc production (tonnes) 2,361 2,576 1,714
Cash cost / Ag oz (US$)2 6.90 12.09 14.77
  1. Metal production is expressed in terms of silver equivalent ounces, (Ag eq oz), the formula for which depends on the gold, silver, lead and zinc metal prices used in each year and hence are only indicative.
  2. Cash costs per ounce of silver is a non-IFRS measure used by the Company to manage and evaluate operating performance at each of the Company's mines. It comprises the cost of production, cost of concentrate transportation and the cost of smelter and refining charges, net of the credit from the sale of by-product metals, (gold, lead and zinc). Refer to the "Non-IFRS Measures" section in our MD&A.

Resource Estimates

The mineralized veins at Topia are laterally extensive and can locally be followed for more than four kilometres. They are steeply dipping and, due to their narrow width, mine development is ‘on-vein’ rather than parallel to it. Consequently, the veins are drilled at wide spacing from surface to trace their lateral continuity, then detail sampled underground as development progresses. Very little underground exploration drilling is conducted. In this way, Inferred Mineral Resources are defined primarily from surface drilling while these are upgraded to Measured & Indicated Resources once the underground sampling is complete. This methodology also proves adequate as a guide to mine planning.


  Tonnes Grade Grade Grade Grade Contained Contained
    Ag (g/t) Au (g/t) Pb (%) Zn (%) Ag eq (oz) Au eq (oz)
Measured 310,600 474 1.36 4.02 4.20 9,920,000 124,000
Indicated 165,300 436 1.34 3.57 3.79 4,850,000 60,625
M&I 475,900 461 1.35   3.87 4.06 14,770,000 184,625
Inferred 400,400 434 1.34 2.86 2.97 10,720,000 134,000


  1. 2018 Mineral Resource Ag eq oz were calculated using 80:1 Ag:Au ratio, and ratios of 1:0.0636 and 1:0.0818 for the price/ounce of silver to price/pound of lead and zinc, respectively. The ratios are reflective of average metal prices for 2018.
  2. CIM Definitions were followed for Mineral Resources.
  3. Area-specific vein bulk densities as follows: Argentina - 3.06t/m3; 1522 - 3.26t/m3; Durangueno - 3.12t/m3; El Rosario - 3.00t/m3; Hormiguera - 2.56t/m3; La Prieta - 2.85t/m3; Recompensa - 3.30t/m3; Animas - 3.02t/m3; San Miguel - 2.56t/m3.
  4. Measured, Indicated, and Inferred Mineral Resources are reported at a cut-off net smelter return (NSR) as follows: 1522 Mine US$193/t, Argentina Mine US$172/t, Durangueno Mine US$144/t, Recompensa Mine US$151/t, Hormiguera Mine US$152/t, El Rosario Mine US$173/t, La Prieta US$235/t, Animas US$149/t, and San Miguel US$248/t.
  5. Totals may not agree due to rounding.
  6. A minimum mining width of 0.30 metres was used.
  7. Mineral Resources are estimated using metal prices of US$1,225/oz Au, US$15.50/oz Ag, US$1.00/lb Pb, and US$1.15/lb Zn; and metallurgical recoveries of 94% for Ag, 60% for Au, 94% for Pb, and 93% for Zn.

Robert F. Brown, P. Eng. was designated as the Qualified Person by Great Panther for the Topia Mine under the meaning of National Instrument 43-101.

NI 43-101 Technical Report on the Topia Mine

Durango, Mexico   |   July 31, 2018

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