Opawica finds high-grade in Brazil

Toronto-based Opawica Explorations (OPW-T) has received positive results from the first phase of due diligence at the Bom Jardim gold property in the Tapajos district of Para state in north-central Brazil.

Results indicate that high-grade and erratic gold mineralization is associated with sulphide-bearing quartz veins. In addition, tailings from artisanal mining operations are mineralized.

The Bom Jardim property hosts eight known gold-bearing quartz-sulphide veins, including Corpo Principal and E-2. The veins are reportedly associated with a major south-southeast-trending shear or fault structure in Proterozoic intrusive rocks. The veins are moderately to steeply dipping, about 1 metre wide or less, and high grade.

To date, Opawica has completed initial sampling of vein material, stockpiles, dump material and tailings from previous and ongoing mining operations, along with a review of present small-scale operations by garimpeiros.

Initial assays confirm that the veins are locally high grade, with a selected sample from a surface stockpile from the Corpo Principal vein assaying 736 grams gold per tonne. A sample of sulphide-poor material collected underground in shaft no. 3 on the Corpo Principal vein assayed 17.5 grams gold over 10 cm. In addition, six auger samples of tailings material from the Corpo Principal vein averaged 25.6 grams gold, suggesting there has been poor gold recovery from the sulphide vein material.

Opawica assayed several samples, which were taken by a Brazilian geologist. Selected samples of sulphide-rich material collected underground at Corpo Principal returned values of between 10 and 95 grams gold per tonne. In addition, a sulphide-rich sample from underground workings on the E-2 vein returned 141 grams gold. This geologist also took three surface samples of finely ground material from leach pads at the E-2 vein; these averaged 2.5 grams gold.

Unfortunately, many of the main workings on the Corpo Principal vein are below 20 metres, and those on the other veins were recently flooded and could not be sampled or mapped. Also, it was not possible to determine true vein widths.

The Tapajos River region has produced up to 30 million oz. gold since 1958. The Bom Jardim property has produced 15,000 oz. over the past three years, primarily from small-scale artisanal workings at quartz-sulphide veins, as well as alluvial and lateritic deposits.

The Corpo Principal vein extends for about 900 metres along strike, and the structure has been investigated and developed by seven vertical shafts to a maximum depth of 50 metres, along with some lateral workings. The vein varies in width between 0.15 and 1 metre. The average grade of the vein material is 134 grams gold per tonne (3.92 oz. per ton).

The E-2 vein is similar in nature to the Corpo Principal vein and has been investigated by the property-owner at three locations. Two surface trenches and a shaft to a vertical depth of 27 metres were excavated over 306 metres of indicated strike length. The average grade of this vein was 136 grams per tonne (3.98 oz. per ton). The grade was 34 grams per tonne (1 oz. per ton) over a section measuring 2 metres high by 2 metres wide by 2 metres long.

Opawica intends to evaluate the 1,440-hectare property further. This work will entail de-watering, sampling and mapping the underground headings, as well as estimating the tailings resource.

Opawica can earn up to a 100% interest in the property, subject to the vendor’s retaining a 25% net profits interest. The company can achieve this by completing a due diligence review, making cash payments to the vendor, and spending $250,000 within 12 months. Additional payments of cash and shares are necessary within the 24-month period following completion of due diligence.

— The author is a Toronto-based freelance writer on mining issues and a frequent contributor to Nickel magazine.