The core has returned 177m grading 1.1 grams per told gold equivalent from 7m, including 15m at 5gpt from 81m with 1.7m at 22.3gpt, revealing the presence of new areas of epithermal gold-silver mineralisation as it drills ahead to the underlying copper-gold porphyry system.

 

"This is a phenomenal result," he said.

 

Limon is a large 1.5km by 1km alteration system that is open to the north, east and west, and there is some evidence of mineralisation to the south from prior drilling.

 

Norris said it could "materially change the Bramaderos project", and he should know, having been involved in the early days at the world- class Cascabel discovery in northern Ecuador and Tujuh Bukit in Indonesia.

 

There are already six different large but lower-grade porphyry targets at Bramaderos but the epithermal discovery opens up a range of new possibilities.

 

Limon has all the right rocks and could compare favourably with Australian deposits such as Cadia East, Boddington and Boda-Kaiser in Australia in terms of grade and tonnes, Norris said.

 

"We are absolutely in the ballpark," he added.

 

Last December, Sunstone announced a maiden resource for its Brama-Alba porphyry deposit of 2.7 million ounces AuEq and set an  exploration target of between 3.3-8.6Moz AuEq, but it also noted that it needed to define higher-grade starter pit areas that could potentially support a development by paying capital costs.

 

"We have a huge upside, we think we can make this a 10Moz district," Norris said. 

 

With success at Limon, 2.7km from Brama-Alba, Sunstone is reviewing is exploration target and expects both tonnes and grade will end up being higher.

 

Sunstone also has two rigs drilling at El Palmar in northern Ecuador, where it is starting to see evidence of Cascabel-style mineralisation, with trace chalcopyrite as it approaches the target zone.

 

The visual copper content appears to be increasing, Norris said.

 

"We should know if it is a significant discovery within weeks," he added.

 

Sunstone shares closed off 3% yesterday at 3.5c, valuing it at $92 million.

 

The stock has traded in a range of 2.7-8.2c over the past year.