Assay results from reverse circulation (RC) drilling at the Castelo de Sonhos (CDS) gold project of TriStar Gold continue to show significant intervals in new holes.
"We're glad that the new drilling is consistent with our exploration target concept," says Nick Appleyard, TriStar's President and CEO. "We've known since last year that we've got considerable potential for growing the resources along the strike of the mineralized conglomerate. But the July results from in-fill holes in the heart of Esperança South now demonstrate significant upside potential even in areas where indicated resources were previously reported. Thick intervals running well above the deposit average point to potential additional resources beyond the pit shell that constrained the 2014 resource."
Drilling will continue through August into early September, reaching a planned 120 to 150 RC holes, at which time a new mineral resource will be estimated, followed by the completion of an initial scoping study (PEA). The PEA is scheduled to be completed before year end.
New reefs identified in heart of the deposit
On this section only one drill hole (CSH-12-083) was previously available for resource estimation; one thick mineralized interval in this hole controlled the location of the pit shell within which resources were reported. New holes within ±50m of this section now make it apparent that the pit shell used for the next resource update will be larger, and will include thick reefs (with true thickness >10m) that lie outside the previous pit shell, with gold grades above the project average. In particular, CSH-17-191 encountered 14m running at an average of 3.2 g/t, with several shorter intervals above 5 g/t.
Grades and thicknesses remain strong in extensions
All RC holes are vertical, and drilled to a target depth of 120m. A few holes were terminated short of their 120m target due to local conditions; any hole that reaches less than half of its target length is deemed to be abandoned prematurely, and will be redrilled. The significant intervals (using a 0.4 g/t cutoff) not previously reported in holes for which assays were available for more than half of the sample intervals.
Several individual intervals in these new holes run above 10 g/t, with CSH-17-188 reaching 27.8 g/t. Some of the individual reefs in these new holes are considerably thicker than the deposit average, which has historically been approximately 4m. With all of the new drilling being vertical, to a target depth of 120m, all of the reported significant intervals are within reach of an open pit. Although diamond drilling has identified strong mineralization below 120m, the upcoming PEA will focus only on a stand-alone open pit mine, and will not address possible longer term potential from underground mining.
Update on new Brazilian mining law
On July 25, 2017, Brazilian President Michel Temer signed into law three provisional measures, referred to as MP 789, MP 790 and MP 791, that affect mining projects throughout the country. They take effect immediately, with Congress being allowed a reasonable period of time to review and amend them.
MP 789 addresses taxation and royalty issues; its principal effect on the Castelo de Sonhos project is to increase the government royalty on gold production from 1% to 2%.
MP 790 modernized the country's mining code, parts of which had become inconsistent with other regulations since it was last updated, more than 20 years ago. These changes include: an initiative to align Brazil's reporting codes with international reporting codes such as NI 43-101; the ability to extend the period during which geology and engineering studies can be done; ending the possibility of a mineral concession being claimed if the holder of the rights is late in filing certain reports; specific guidance on mine closure; and changes to the schedule of reporting deadlines. All of these are helpful to TriStar as it works to advance the Castelo de Sonhos project.
"We welcome all of these changes," says Nick Appleyard. "They improve transparency in the regulatory framework, and are designed to relieve companies and the regulators from political pressure. All of this should make it easier and quicker for us to bring Castelo de Sonhos through the feasibility and permitting process, and to construct a successful and profitable mine."