The Collingwood property is located in an area prospective for gold-base metals in the northwest Nelson region, South Island, New Zealand. Covering an area of over 167.5 km2 in the coastal foothills of Golden Bay, the property is irregularly shaped and also comprises six smaller parcels discontinuous from the main body of the property. The property encompasses the lower 25 km reaches of the Aorere River valley (see property map).
Superior was issued the Exploration Permit (EP 52218) for the Collingwood property in mid-December 2010.
Gold was produced historically from the Aorere Valley, initially through alluvial gold workings scattered throughout the property area, and later from hard-rock deposits in the hills and on the valley sides. In 1856 the Aorere Goldfield became the first officially proclaimed goldfield in New Zealand, with alluvial gold first discovered near the confluence of Lightband Gully and Appos Creek. This sparked a small gold rush with about 1,500 miners converging on the district and the recovery of about 24,000 oz of gold (NZ Mines Department, 1887) over the following decade, before the more easily won gold was exhausted. The actual gold rush itself lasted for 3 years, during which Collingwood was touted as the capital of New Zealand, however the spectacular finds in Otago and the West Coast around Ross subsequently drew the miners away.
The majority of the detrital gold was won from basal quartz conglomerates and river terrace deposits amenable to sluicing operations. The more prominent of these sluicing operations were located at Appos Flat and the lower reaches of the Slate River. According to MRC Ltd (1907), the Golden Gully mine peripheral to Appos Flat produced 40,000 ounces of gold in approximately seven months from an area of only 4.2 hectares.
Exploitation of a gold-bearing gossan at Johnston's United recorded production of 18,745 oz of gold at an average grade of 9.4 g/t from 1869 to 1896. Other mined areas reported only minimal gold production, with quartz reefs at the Phoenix mine assaying up to 4.6 g/t gold, but which were too small to sustain any significant development. Limited siliceous gossan material from the Ophir mine was processed, but no production figures were recorded. Two shafts were sunk into silver-lead lodes in 1875 at Richmond Hill, but development was limited because of erratic silver grades.
Several companies ccarried out exploration in and around the property area over the period from 1974 to 2007. The historical Johnston United-Ophir mine workings have been the subject of at least three exploration campaigns by different groups. Exploration has targeted the concept of bulk tonnage low-grade gold deposits in the form of precious/base metal sulfide mineralization hosted by metamorphised turbidites, akin to the prospective Mt Read Volcanics of Western Tasmania, which hosts the Rosebery, Hellyer and Que River deposits. Exploration activities included detailed geologic mapping and sampling of underground and surface workings/mineralization, ground geophysical surveys and limited diamond drilling programs.
Exploration in the late 1960s to early 1980s discovered a number of porphyry molybdenum deposits in the district. Mineralization typically occurs as molybdenite disseminations in joint-controlled quartz vein stockworks, with accessory pyrite, chalcopyrite, pyrrhotite and rare galena, sphalerite, and bismuth (Rabone, 1989a).
The old Aorere Goldfields are noteworthy on several counts: this was the country's first major goldfield, it was the first at which sluicing was used, and the first at which the miners collaborated to set down their own regulations. Interesting, too, is the fact that both quartz and alluvial gold occurred close together, and that other minerals, particularly silver, were also mined there.
The Aorere Valley is a 5-km wide valley extending inland from Collingwood, Nelson. It has been filled to a considerable depth by river gravels and sands and young rocks. The foundation (or geological 'basement') of the valley is composed of hard old rocks, which also form the hills to the south-east. About 350 to 300 million years ago, and again about 120 to 100 million years ago, granites were intruded into the Ordovician and other rocks. The heat emanating from the granites altered many of the rocks to form metamorphic rocks. Intrusion of the granites was also accompanied by widespread mineralisation, with the formation of silver, gold, copper, zinc, lead, iron, nickel and tungsten in many areas of north-west Nelson. Mineralisation of the Ordovician rocks is the source of much of the alluvial gold found in many of the streams flowing out of inland Golden Bay.
Preliminary exploration programs will comprise remote sensing studies, airborne geophysical surveys, bulk sampling of prospective alluvial areas, along with reconnaissance to semi-detailed geological mapping and sampling programs. Where justified, the hard-rock exploration process can subsequently be fast-tracked by using portable diamond drill rigs to test sub-surface extensions and continuity of defined surface mineralization.
