Exploration junior Stavely Minerals (ASX: SVY) has hit a significant zone of bornite during recent drilling at its Thursday’s Gossan porphyry copper and gold deposit in western Victoria.
The company today reported a diamond drill hole at the prospect within its wholly-owned Stavely copper-gold project intersected more than 110m of copper sulphide mineralisation including a wide 44m zone with trace-to-moderate chalcopyrite and bornite mineralisation.
Stavely Minerals executive chairman Chris Cairns said this was the first significant bornite interval ever seen at the deposit and represents an “exciting new development in the company’s ongoing patient search for a world-class porphyry discovery”.
“This is clearly the best interval we have drilled to date and we are confident that the copper assays will reflect the better developed chalcopyrite and bornite mineralisation,” he said.
“The unknown factor, as we have been saying for some time now, is that we expect substantially better gold grades in zones of bornite mineralisation,” Mr Cairns added, saying this could only be verified when the laboratory assays are received in a few weeks.
In the meantime, Stavely is planning to shortly collar a new drill hole to target what it believes is the “core of the porphyry intrusion to the south”.
Current drilling program
The current drilling campaign at Thursday’s Gossan is aiming to progress into the hotter part of the mineralised porphyry system, which is expected to contain higher-grade copper and significantly higher-grade gold.
The current drill hole SMD044 was planned to test a target zone previously targeted by failed drill holes SMD033 and SMD034 late last year.
It is located about 200m south of previous hole SMD028, which returns intercepts including 73m at 0.32% copper and 0.13 grams per tonne of gold from 577m, including 6m at 1.12% copper, 0.44g/t gold and 12g/t silver from 577m.
According to Stavely, the encountered chalcopyrite/bornite mineralisation at SMD044 is interpreted as “wall rock mineralisation” and the causative porphyry intrusion, which should contain the hottest and best-developed mineralisation, remains to be seen.
The company believes this porphyry intrusion may be located to the south of SMD044 and will be targeted by the next hole, SMD045.
The Stavely copper-gold project has an inferred shallow copper resource of about 28 million tonnes grading at 0.4% copper for 110,000 tonnes of contained copper.
Bornite, also known as peacock ore, is an important copper ore mineral that occurs in porphyry copper deposits along with the more common chalcopyrite.