GOLD AND PRECIOUS METALS — Mispec tests targets at Jampang

What copper-gold porphyry deposits lack in grade, they more than compensate for in volume, making them one of the most sought-after geological targets. For this reason, Mispec Resources (MPE-M) has set its sights on porphyry targets at its Jampang property on the Indonesian island of Java.

Jampang lies 150 km south of the capital, Jakarta, and covers 20,530 ha spread over six Mining Authorizations (KPs). The property holds a resource estimated at 8 million tonnes grading 2.4 grams gold per tonne in three closely spaced zones.

Originally, Mispec credited the deposit’s formation to a high-level epithermal mineralization event. However, new data from drill core indicate the possibility of a deeper level of formation.

“Fluid inclusion and geothermometry work show much higher temperatures than those reached in epithermal environments,” says James Patterson, Mispec’s vice-president of exploration. “Mineralogical studies also show stannite (a copper-iron-tin sulphide) and bismuth to be present [and] associated with porphyries, so we’re much lower in the system than we originally thought.” Patterson says one of the reasons for applying the epithermal argument stemmed from the prevailing view at the time Mispec entered Indonesia two years ago that porphyries do not occur on Java. However, four porphyry discoveries have been made since that time, one of them on a property abutting Jampang’s western border.

That property, which is owned by Omax Resources (OXR-V) and

Australian-listed Meekatharra, was tested last fall by eight drill holes.

Each intersected large widths of copper-gold porphyry, but assays proved uneconomic. Nevertheless, Patterson is optimistic of his company’s chance of success.

“This was the first porphyry drilled [in Java] and the major part of it seems to occur on our property,” he says. “And even though it wasn’t ore grade, they pulled up 300 metres of the stuff; the model is right and all we have to do now is pump the grade a bit.”

The southernmost portion of the deposit also returned copper grades as high as 3.6% copper over 2.7 metres, including 1.32 grams gold and 29.8 grams silver. The widest copper-rich interval was 30 metres grading 2% copper.

More recently, the company has focused on the Cilubang area, about 4 km southeast of the Jampang deposit. There, recent surface mapping has led to the discovery of several outcroppings of mineralized andesitic lapilli tuff intruded in places by quartz-hornblende. Results from several grab samples of gold and sulphide-bearing quartz veins in the tuff varied between 0.1 and 7.9 grams gold.

The quartz veins strike for 700 metres and are described as predominantly massive with local comb-textured breccia. They contain locally abundant pyrite, with lesser amounts of chalcopyrite, galena and sphalerite, and a thin layer of clay-pyrite alteration occurs adjacent to the veins. Further to the west, outcroppings of altered dacite were discovered during the 1997 field season. One sample of quartz stockwork in the intrusive averaged 11.2 grams gold.

Patterson says that one of the key pieces of evidence for a porphyry underlying Jampang is that the deposit and all of the mineralized showings on the property coincide with a broad anomaly of low magnetic signature. The anomaly is interpreted to reflect an alteration zone associated with an intrusive.

Mispec is currently cutting a 1.5-km-by-800-metre grid in the central part of the anomaly, where the outcroppings of lapilli tuff were found. A geochemical survey and ground geophysical survey will follow.

The company is also attempting to correlate the copper zones in drill core in order to better understand their geological characteristics.

“We want to find out fairly soon whether this porphyry is 100 metres or 1 km underground,” says Patterson, “and whether it carries values or not.” Mispec can earn up to a 90% interest in the property by issuing 20 million shares to its current joint-venture partner, Hunamas Putra Interbuana. If approved by regulatory bodies, the issuance would nearly double the company’s outstanding shares to roughly 43.9 million (or 46 million shares fully diluted). The remaining interest in the property is held by the state-owned mining company Aneka Tambang.