Bluestone Resources (TSXV: BSR; US-OTC: BBSRF) has tabled a new resource estimate for its Cerro Blanco underground gold-silver project in Guatemala, upgrading resources to the indicated category and adding 308,000 oz. gold to the inferred category.
The project now contains 3.7 million measured and indicated tonnes grading 10.1 grams gold per tonne and 37.9 grams silver for 1.2 million oz. gold and 4.5 million oz. silver, with more than 96,000 oz. gold in the measured category.
The project also contains 1.3 million inferred tonnes at 8.1 grams gold and 23.6 grams silver for 357,319 oz. gold and 1.04 million oz. silver.
"These significant improvements over the 2017 estimate are a result of an improved 3D geological understanding of the deposit owing to all of the structural geological work, mapping, sampling, and infill drilling we have completed," Bluestone president and CEO Darren Klinck said in a press release.
The company also calculated a separate, bulk-tonnage resource estimate that includes lower grade mineralization in the project's overlying silicified cap as well as low-grade envelopes around the high grade veins. Although the company is working toward feasibility focused on underground mining, it says the bulk tonnage resource represents a "future opportunity" if it ever considers mining from the surface.
According to the bulk tonnage estimate, Cerro Blanco contains 60.5 million measured and indicated tonnes grading 1.5 grams gold and 7.1 grams silver for 2.9 million oz. gold and 13.8 million oz. silver.
The resources come as a result of nearly 130,000 metres of drilling by Bluestone and past operators. The company's recent infill program included more than 12,500 metres across 28 undrground holes and 30 surface holes.
The company tabled a preliminary economic assessment for Cerro Blanco in February 2017. According the report, the project has a US$317 million after tax net present value at a 5% discount rate and a 43.9% after tax internal rate of return.
Shares of Bluestone are currently valued at $1.39 with a 95 ? to $1.60. The company has an $89 million market capitalization.