Sunstone Metals Ltd (ASX:STM) has delivered broad gold and copper assays from four more holes in the upper 500 metres at El Palmar Project in Ecuador, confirming the project as a "substantial" porphyry discovery.
The latest assays extend the known, continuous mineralisation to an area of at least 500 x 300 metres with 500 metres of vertical extent from surface, and include:
- 167 metres at 0.57 g/t gold and 0.14% copper from 112 metres;
- 165.9 metres at 0.58 g/t gold and 0.15% copper from 19.1 metres, including 78 metres at 0.79 g/t gold and 0.17% copper from 95 metres;
- 243.9 metres at 0.43 g/t gold and 0.12% copper from 13.1 metres, including 58 metres at 0.64 g/t gold and 0.13% copper from 95 metres; and
- 162.05 metres at 0.38 g/t gold and 0.13% copper from 10.15 metres.
In addition, early-stage deep drilling has intersected peripheral mineralisation in wall rock that is interpreted to be close to higher grade mineralisation, providing further exploration targets at depth.
Moving forward, Sunstone’s cash and equity investments remain strong at $30 million, allowing expanded exploration activities at both El Palmar in northern Ecuador and Bramaderos in southern Ecuador.
Project location in Ecuador.
“Project of immense scale”
Sunstone MD Malcolm Norris said: “These latest results confirm El Palmar is a substantial project of immense scale with grades which are in line with those seen in many of the world’s high-profile porphyry deposits.
“And there is huge scope to continue growing the discovery, with the strong result from hole EPDD011 opening up the eastern and north-eastern sectors for further drilling.
“This area will be explored initially with an undercut hole, with further drilling targeting untested magnetic anomalies and surface gold-copper soil anomalies in this area.”
Norris said the discovery was shaping up as a series of targets across an extensive vertical and lateral interval of the 750-metre diameter El Palmar intrusive complex and additional satellite targets.
He added: “We continue to expand the zone of porphyry gold-copper mineralisation.
“The targets in the upper 500 metres in the southeast and eastern sectors have a clear relationship between gold, copper and magnetite and so drill targeting is aided by our robust 3-D magnetic model.
“The success of this approach is shown by the results in this release from holes EPDD007, 008, 010 and 011.”
Drill results
The latest El Palmar results comprise all assays from drill holes EPDD007, 008, 010 and 011 in the upper 500 metres zone of the southeast sector and holes EPDD009 and 016, which drilled deeper into the El Palmar system in the central sector.
Drill hole EPDD010 was drilled over and to the south of EPDD002, 006 and 007 and also defined continuity of mineralisation both above and south of EPDD002.
Drill hole EPDD011was drilled to the north and into a previously undrilled area. This hole was drilled at a shallow angle of -350 and, as such, has defined a broad mineralised zone which will now be explored to depth.
Notably, all holes within the south-eastern and eastern portions of the El Palmar intrusive complex have defined strong mineralisation from surface
Drill hole EPDD009 was drilled to test a deep magnetic anomaly below and west of the two shallower mineralised zones in EPDD004, but the hole deviated and lifted so that it passed over the upper section of the anomaly.
Nevertheless, EPDD009 intersected 513 metres at 0.17 g/t gold and 0.09% copper from 225 metres, including 68 metres at 0.14 g/t gold and 0.1% copper within a syn-mineral bi-modal quartz diorite body.
The broad interval of 513 metres of anomalous gold and copper comprises two of these syn-mineral intrusives and the intervening mineralised wall rock.
Drill hole EPDD016 was drilled to test a sub-vertical magnetic anomaly in the northwest area of the El Palmar target.
The hole intersected two phases of diorite with variable veining, and traces of chalcopyrite and molybdenite to the end of hole at 974 metres.
El Palmar cross-section.
What is next?
Several highly prospective satellite anomalies that are also related to deeper magnetic bodies will be drilled in 2022
Sunstone will also begin exploration of compelling epithermal targets on the northern part of the concession where historical surface rock chip results yielded encouraging results.
Furthermore, new assay results from the Bramaderos Project are expected within a fortnight
Norris adds: “Targets below 500 metres were less well defined in magnetics, but a large Spartan magnetotelluric (MT) survey had just been completed which maps conductivity and resistivity.
“This will now be integrated with magnetic models to deliver higher confidence deep drill targets.
“We have identified clear extensive intervals of deep gold and copper mineralisation in holes EPDD009 and 016 to depths of up to 900 metres.
“For example, EPDD009 intersected 513 metres at 0.17 g/t gold and 0.09% copper from 225 metres. Such long intervals of mineralisation are typical in the adjacent wall rocks to syn-mineral porphyry intrusions.
“We expect these relate to adjacent zones of better mineralisation that are yet to be drilled within the El Palmar intrusive complex.
“Our exploration program will now focus on defining drill targets in this domain.”