Barra Grande yields small stones

Toronto-based Trans Hex International (THI-V) has processed 31 of 172 samples from the first pit at the Villa Barroso target on the Barra Grande diamond project in Brazil’s Minas Gerais state.

So far, 2,430 cubic metres of bank material from level 5 have yielded 28 diamonds totalling 14.9 carats, for an average grade of 0.61 carat per 100 cubic metres and an average stone size of 0.53 carat. The largest stone recovered weighed in at 1.55 carats. Level 5 is a 1-metre-thick intermediate gravel body. It contains the target’s highest heavy mineral content.

Trans Hex notes that, although commercial grades are not yet emerging from level 5, results indicate that the average stone size is reasonably large and all of the stones are of gem quality.

The 172 samples comprise a 16,800-cubic-metre bulk sample of intermediate and basal gravels from the first trench. The sampling program is aimed at providing an initial estimate of diamond grades and values. The samples were processed in a 15 tonne-per-hour, run-of-mine pan plant, which, along with a slimes dam, was completed in January.

Diamonds at Barra Grande are hosted in a 3-to-5-metre-thick, matrix-supported gravel horizon on an undulating red argillic bed of variable thickness. The argillite, in turn, rests on an uneven sequence of basaltic volcanics. Regional and infill drilling have indicated total gravel resources of at least 100 million cubic metres in the three targets at Barra Grande.

Earlier this year, Trans Hex exercised its option for a half-interest in the project, having fulfilled a US$2-million spending requirement. The company’s interest rose to 60% after Verena Minerals (YVM-V), the vendor, failed to secure its share of funding.

Verena plans to raise $1 million by issuing 3.3 million units via a private placement. One unit consists of one share and two-thirds of a share purchase warrant. One warrant allows the holder to buy another share at 40. The financing is subject to regulatory approval.

Verena has the right to recover the 10% within 90 days of receiving a bankable feasibility study. Should it choose to do so, it must repay its pro rata share of funding, plus 50% of that amount, as a penalty.

Processing of samples from the southern site will continue through June. The plant will then turn to samples collected from a northern site. Those results are expected in November.

During March, three samples of gravel, totalling 1,200 cubic metres, were excavated from the Sertaozinho artisanal mine site. Ten diamonds totalling 3.1 carats were recovered. The average grade of the basal gravels (784 cubic metres) was estimated at 0.35 carat per 100 cubic metres. The average stone size was pegged at 0.34 carat.