|
King-king |
|
|
Mindanao, Philippines |
| Main commodities:
Cu Au
|
|
 |
|
|
 |
Super Porphyry Cu and Au
|
IOCG Deposits - 70 papers
|
All papers now Open Access.
Available as Full Text for direct download or on request. |
|
|
The King-king porphyry copper-gold deposit is located in the southeast of the island of Mindanao, 35 km east of Davao City across the Davao Gulf, and 11 km inland of the western coast of the southeastern peninsula of the island (#Location: 7° 11' 27"N, 125° 58' 19"E).
The King-king deposit was discovered during an exploration program carried out by the Philippines company Nationwide Development Corporation (NADECOR) between 1966 and 1968. Between 1969 and 1972, Mitsubishi Mining Corporation drilled 54 diamond drillholes and conducted metallurgical studies, but subsequently withdrew. In 1981, NADECOR entered into an Operating Agreement with Benguet Corporation. Between 1991 and 1994, Benguet drilled 69 diamond drill and 25 reverse circulation holes, and completed an in-house feasibility study. In 1992 a Mineral Production Sharing Agreement (MPSA) was signed between NADECOR (as Leaseholder and Contactor), Benguet (as Operator) and the Philippines Government. Between 1995 and 1997, Echo Bay Mines, Inc. obtained an option on the project and drilled 128 holes (52 718 m) and completed a Feasibility Report. Upon the acquisition of Echo Bay by Kinross Gold in 2003, the latter waived its option to proceed with the King-king project. In 2009 NADECOR and Russell Mining and Minerals, Inc. signed a letter of intent to work together to develop the project. In 2010, after little activity on the project, the Philippines Department of Environmental and Natural Resources ordered NADECOR to develop and start a work program, and Benguet to hand over possession in order to allow for immediate resumption of the project. Russell Mining and NADECOR signed an agreement for the former to earn up to 60% of the project, while Russell Mining, NADECOR and Benguet reached a settlement agreement, wherein Benguet relinquished their right, title and interest in the project and in the Operating Agreement. Russell Mining assigned its interests in the Project to Ratel Gold Limited and took over management of Ratel, which changed its name to St. Augustine Gold and Copper Limited, a publicly traded company on the TSX. In March 2015, the Philippines Environmental Management Bureau approved the King-king Environmental Impact Statement, and issued King-king’s Environmental Compliance Certificate. In August 2016, the Philippines Mines and Geosciences Bureau renewed the Mineral Production Sharing Agreement (MPSA) over the King King deposit held by NADECOR and St Augustine Gold and Copper. However, in February 2017, the Philippines Department of Environment and Natural Resources announced it would cancel 75 MPSAs throughout the country on environmental grounds, "to keep the country’s watersheds off-limits to destructive mining". One of these MPSA's was the King-king title. No further development plans for the project have been sighted, although St. Augustine continues to report it as an asset.
Regional Setting
The southeastern Mindanao Peninsula is bounded by two parallel subduction systems – the north-south trending East Mindanao trench, which is a segment of the Philippine Trench, located off the east coast of Mindanao, and the sub-parallel north-south trending Davao Trench below the Davao Gulf. The latter is expressed as the Philippines Fault that extends over the length of the Philippines, from southern Mindanao to northern Luzon. The King-king deposit is located on the western flank of the eastern Mindanao Cordillera that forms the core of the peninsula. King-king is the most southerly of a 75 km long, NNW-trending, group of porphyry copper and gold deposits that runs across southeastern Mindanao. The King-king district itself is bounded by two major splays of the Philippines Fault that make it a tectonically-active arm. One is ~20 km to the east, whilst several km to the west, a north-south thrust fault runs parallel to Davao Gulf, with King-king located on the over-riding side.
The geology of the western Mindanao Peninsula includes:
• Inliers of pre-Jurassic amphibolite schist, after ultramafic and mafic protoliths;
• Significant areas of Cretaceous greywacke, with shale interbeds and spilitic pyroclastics. These are the principal country rocks surrounding the King-king deposit;
• Cretaceous to Paleocene ultramafic and mafic rocks;
• Paleocene to Eocene marine deposits, largely wackes and shale, with minor basal conglomerates, reef limestone and calcarenites;
• Oligocene to Miocene, largely tuffaceous, sandstones and marine clastics;
• Upper Miocene to Pliocene, largely tuffaceous sandstone or marine clastics;
• Upper Miocene to Pliocene hypabyssal felsic intrusions, generally dacitic with andesitic plugs;
• Pliocene to Pleistocene marine and terrestrial sedimentary rocks with local coraline limestone.
Geology
The main King-king deposit is a low-pyrite porphyry copper system with locally significant associated gold, and is the largest of several prospects associated with mineralised intrusives distributed along a NE-trending belt measuring some 6 x 3 km. These mineralised intrusives have been emplaced within a folded Cretaceous to Paleocene volcano-sedimentary sequence, apparently along pre-existing NW-trending anticlinal axes, which have been eroded to expose the intrusive cupolas. The intrusions are believed to have been emplaced during the middle- to late-Miocene.
The deposit, as defined by a 0.2% Cu cutoff, is elongated along a 110° trend with dimensions of ~1800 x 250 to 550, averaging 400 m and an apparent steep NE dip. It has been split into 5 zones, namely, from west to east, Tiogdan, Casagumayan and Lumanggang, forming a linear, inter-connected mineralised zone, with a fifth, Bacada, being immediately to the south of Lumanggang. The sixth, Bibutaan, is separated and ~500 m to the north of Casagumayan. The deposit has also been subdivided into two, based on grade distribution, namely,
i). an eastern segment (corresponding to Lumanggang), where Cu mineralisation is generally very erratic, and where the better gold grades occur in pockets, usually associated with localised zones of strong silicification and quartz stockworks; and,
ii). the western segment, within the Casagumayan and Tiogdan areas, which generally carries higher copper and gold values and is more uniformly mineralised. These two segments are alternatively interpreted to represents parts of the same body, or to be related to two or more adjoining mineralising systems associated with separate, though probably related, intrusions.
The deposit is predominantly hosted by an elongate, dyke-like, 120° striking, diorite intrusive complex, and to a lesser extent, by the intruded volcanic and sedimentary country rocks. The diorite complex comprises a biotite diorite porphyry and accompanying hornblende diorite and diorite porphyry, which are late magmatic differentiates of the former. Local brecciation accompanied the diorite intrusions into the predominantly volcanic wallrocks, resulting in the development of intrusion breccia along the contacts. The volcanic country rocks comprise NW striking and SW dipping pyroclastics, mainly tuff and lithic tuff, with andesitic flows and intercalated sedimentary rocks, mostly wackes. Reversals of dip is locally common, forming minor anticlines and synclines south of the main King-king deposit. These country rocks have not been identified within the ore zone, where alteration has obliterated the textures of the protoliths. Intrusion of the dioritic complex continued beyond the emplacement of porphyry copper mineralisation, as evidenced by the presence of post-mineral hornblende diorite porphyry, diorite porphyry and dacite porphyry, which occur as peripheral stocks bounding the Lumanggang and Bacada areas, and as northwest-trending lenticular bodies or dykes flanking the porphyry mineralisation. One 5 to 15 m wide hornblende diorite porphyry dyke has been traced for >1000 m along and within the southern flank of the deposit. Elongate hornblende diorite stocks bounding the southern and western margins of Bacada also trend NW.
The principal lithologies have been described as follows:
Diorite Complex
• Syn-mineral Biotite Diorite Porphyry - the main intrusive at King-king, and the most important host to Cu-Au mineralisation. It is generally brownish, and medium- to coarse-grained, and is characterised by ~10% primary 'book' biotite. It is crumbly in the near-surface when not silicified, or when lacking well-developed quartz veinlets. Along or near the contact with the volcanic wallrock, it commonly exhibits strong breccia texture with pebble- to occasional cobble-sized angular xenolithic fragments that are tightly welded in the rock matrix. These clasts are fragments of the intruded country rocks that were traversed by the magma during intrusion. Copper mineralisation within this intrusive is predominantly bornite with subordinate chalcopyrite, usually occurring as fracture fillings. Bornite appears to increase towards the western half of the orebody from the Casagumayan to the Tiogdan zone. Copper and gold grades within this intrusive average 0.37% and 1.17 g/t respectively.
• Intra-mineral Hornblende Diorite Porphyry - which occurs as stocks within the centre of the Lumanggang and Casagumayan zones. It is brownish-grey, porphyritic, and medium- to coarse-grained, with large subhedral plagioclase (andesine) and hornblende phenocrysts, occurring in an interlocking feldspathic matrix. Thin sections indicate the hornblende phenocrysts comprise 10 to 20 vol.% of the rock. Locally, it contains 1 to 3 vol.% primary biotite. Where the Main orebody is developed within this rock type, grades average 0.37% Cu and 0.44 g/t Au.
• Intra-mineral Diorite Porphyry - which has a lighter colour, a relatively finer matrix, more dispersed plagioclase (andesine) and hornblende phenocrysts compared to the Hornblende Diorite Porphyry, whose hornblende is more tightly packed. It contains 3 to 5% hornblende which has locally been entirely altered to secondary biotite, leaving a plagioclase-dominated texture. It locally has a smooth line contact with the Hornblende Diorite Porphyry, although the contacts are predominantly gradational. In some intersections. Hornblende Diorite Porphyry clasts are found within the Intra-mineral Diorite Porphyry. The Intra-mineral Diorite Porphyry is the least mineralised of the intrusives, with grades in the ore zone averaging 0.37% Cu and 0.38 g/t Au.
• Intra-Mineral Dacite Porphyry - which appears to be only a minor intra-mineral intrusive occurring as a series of dykes with well-defined contacts cutting the Biotite Diorite Porphyry. It is generally massive, coarse-grained and porphyritic, with large euhedral to subhedral plagioclase (andesine) phenocrysts that are as much as 0.5 cm in size, which with hornblende, are set in a fine feldspathic matrix. Contained mineralisation is predominantly fracture filling with almost equal amounts of bornite and chalcopyrite. Accompanying alteration is propylitic, similar to that of the post-mineral dacite porphyry mapped external to the mineralisation, where chlorite, epidote and calcite are the predominant alteration assemblage. Where bornite is the predominant mineral, copper grades are generally >0.2% with occasional values of >1% Cu near contacts with the intruded Biotite Diorite Porphyry.
• Intrusion/Hydrothermal Breccia - drilling at Lumanggang has encountered hydrothermal breccias, or breccia pipes, that have been interpreted to be intra- to late-mineral. The largest of these breccias appears to have a 40 x 60 m, 60° elongated, elliptical shape in plan. Clasts are pebble- to cobble-sized, angular, and dominated by volcanic rocks which occasionally carry copper oxides and Intra-mineral Diorite Porphyry fragments. The clasts have commonly been rotated, with rounded edges, rimmed by rock flour, although, tightly welded pebble- to cobble-size angular to sub-angular fragments are also evident. Grades range from 0.04 to 0.68%, averaging 0.27% Cu, and from trace to 0.6, averaging 0.21 g/t Au.
• Post-Mineral Diorite Porphyry - which occurs to the west of the ore zone in the Lumanggang Zone, and extends towards Binutaan, as a NW-trending, 900 x 60 to 120 m stock. It is coarser than the Intra-mineral Diorite Porphyry, has only undergone weak propylitic alteration, and is essentially barren of sulphides. It generally has a greenish hue, due to chlorite diffused in the matrix, with local specks of epidote. It contains >25% oligoclase to andesine plagioclase and 2% quartz.
• Post-Mineral Hornblende Diorite Porphyry - which is greenish-grey, and is megascopically similar to the Intra-mineral Hornblende Diorite Porphyry, except that it has only been subjected to propylitic alteration, and is not mineralised. It commonly contains specks of disseminated epidote. It is distinguished from the Diorite Porphyry, which only carries 1 to 2% hornblende, by the presence of ≥10% hornblende phenocrysts, and by the presence of relatively euhedral plagioclase laths. It is located on the western flank of the mineralised diorite complex, but also occurs as dykes within the mineralised zone. Both the main mass and dykes appear to have been influenced by a pre-existing NW-trending fracture system, as seen to the east and south of Bacada. Everywhere encountered, the copper grade drops drastically to <0.1% Cu inside of this intrusive phase.
• Post-Mineral Dacite Porphyry - characterised by large, up to 0.5 cm, subhedral plagioclase and hornblende phenocrysts set in a fine- to medium-grained feldspathic matrix. The plagioclase occurs as medium to large sub-angular to sub-rounded crystals, with up to 10% medium- to large-phenocrysts of sub-angular to sub-rounded primary quartz. The rock is propylitically altered, characterised by matrix epidote and chlorite, and calcite in microveinlets.
Sedimentary and Volcanic Country Rocks
• Pre-mineral Tuff and Andesite Country Rocks, that are dominated by greenish to brownish-grey pyroclastic and lithic tuff, and andesite flows. The tuffs are massive to bedded, fine-grained to aphanitic and, where relatively unaltered, grey to dark-grey. Locally they are lithic. The andesite flows are either aphanitic or porphyritic, with medium-sized plagioclase phenocrysts in the latter, and no recorded intrusive contacts noted between the tuff and andesite. These volcanic rocks generally strike NW, with moderate to steep SW dips, except where locally folded to dip north. Sulphide mineralisation within the volcanic rocks is generally confined to the contact zone with the intrusive complex, with grades ranging from 0.06 to 0.84, averaging 0.22% Cu total and; from trace to 0.87, averaging 0.18 g/t Au.
• Pre-mineral Sedimentary Rocks, which overlie, but are also locally intercalated with, the the volcanic rocks surrounding the deposit. The sediments are generally thinly and rhythmically bedded. Individual beds locally contain 1 mm diameter greenish to reddish volcanic fragments. The sedimentary rocks generally strike NW and dip SW, although dip reversals to the NE are common due to localized steep folding, particularly to the south of the main deposit. Clastic rocks include arkosic greywacke, feldspathic wacke, lithic wacke, tuffaceous siltstone and shale. These rocks contain 12 to 35% plagioclase, as well as accessory quartz and hornblende and rare pyroxene and biotite. The rock fragments, that comprise 10 to 15% of the lithic wacke, are andesitic.
NOTE: Ibrado, et al. (2013) and Hester, et al. (2010) have described intra- and post-mineral Hornblende Diorite Porphyry, Diorite Porphyry and Dacite Porphyry as separate phases/pulses. It is uncertain if this is only based on the presence or degree of alteration and mineralisation, or if intrusive relationships between the interpreted intra-mineral and post-mineral bodies of each of the lithologies have been observed. Ibrado, et al. (2013) state that the "post-mineral hornblende diorite porphyry, diorite porphyry and dacite porphyry occur as peripheral stocks bounding the Lumanggang and Bacada zones, and as northwest-trending lenticular bodies or dykes flanking the porphyry mineralisation". This may imply intrusions of a given composition are mapped as intra- or post-mineral based on their proximity to the mineralised system.
Structure
The major faults within the main King-king deposit and it's immediate surrounds are generally NW-trending and dip steeply to the NE. These faults, where within the deposit, show localised silicification with associated quartz veinlets along their walls. The second major set of faults at King-king trend NNW. However, the dominance of the NW set is reflected in the preferred orientation of the post-mineral Hornblende Diorite Porphyry dykes, the epithermal quartz stockwork zone in the Casagumayan and Tiogdan zones and the elongation of the entire main deposit. The same trend is also expressed by the Post-mineral Hornblende Diorite Porphyry stocks situated peripheral to the main King-king deposit. These NW-trending structures played an active part during the emplacement of the mineralised diorite complex and the post-mineral intrusives. The NNW faults, appear to have also influenced to some extent the emplacement of the Hornblende Diorite Porphyry as indicated by the dykes near Tiogdan.
On a district-wide scale, the NW fabric defines the orientation of the faults and veins, and orientation of the longer axes of post-mineral diorite stocks in Binutaan to the north. Folding is evident outside of the main King-king deposit, with axes generally trending NW, and localised deviations to the east and west.
Alteration
Four major and two locally overprinting hydrothermal alteration styles have been defined in and around the main deposit. From the central core, outwards, these are:
• K Silicate (Potassic) Alteration, which predominates in the mineralised diorites, particularly the biotite diorite porphyry, and the volcanics that are close to the intrusive contacts. It comprises quartz-sericite-biotite (±K feldspar), with chlorite, magnetite, ±epidote, ±pyrite, and accompanies the bulk of the sulphide mineralisation of the deposit. It is divided into two sub-zones, namely the:
- K Feldspar Sub-Zone which defines the central core of the main mineralised body and is also central to the alteration system. It is characterised by megascopic K feldspar, which occurs along fractures lined with quartz veinlets, as spots partially rimming primary plagioclase, and as complete matrix replacement, giving the rock a pinkish hue. Locally, the K feldspar is so intense as to impart an almost uniform pink colouration. Stain tests from this sub-zone show K feldspar contents ranging from 5% to as high as 90%.
- Biotite Sub-Zone, which envelopes the K feldspar core, and is generally characterised by pervasive and interstitial secondary biotite and sericite occurring as dispersed flakes; shredded disseminations; or pigment-like infusions within the matrix; and as partial to complete replacements of hornblende. Chlorite locally partially replaces biotite or alters the plagioclase, whilst sericite, where pervasive, almost totally replaces the plagioclase. Quartz is found within the biotite sub-zone as matrix replacement and as microveinlets. Magnetite occurs as disseminations, micro-fracture fillings, and locally as small clots, intimately associated with chlorite-altered biotite. Epidote occurs as disseminations, fracture fillings and as flakes, sometimes attached to chalcopyrite and bornite on the walls of the quartz veinlets and quartz vugs.
• Quartz-Sericite-Chlorite Alteration, which comprises a quartz, chlorite, sericite, ±pyrite, ±magnetite, ±biotite, ±epidote assemblage. This alteration is responsible for a generally light greenish grey to greenish colour in the altered rocks, with a local brownish tinge from relict biotite specks and/or disseminations. This zone largely envelopes the K silicate alteration zone, both vertically and laterally. Quartz is mainly found as replacements and veinlets, whilst sericite and chlorite are pervasively dispersed in the matrix. Pyrite, whilst ubiquitous but generally <1 vol.%. Chlorite and sericite, ±magnetite, are more abundant along micro-fractures rather than in the matrix.
• Sericite-Clay-Chlorite Alteration overprints both the K silicate and Quartz-Sericite-Chlorite alteration, and imposes a pale greenish white or off-white colour. It renders the rock crumbly, particularly in zones with very weak silicification or veinlet development. Pyrite is weak to absent, whilst magnetite is found as veinlets or as disseminations that are partially to wholly altered to hematite. Relict biotite occurs as brownish patches in the less weathered outcrops. Epidote is commonly seen in the matrix, and occasionally in fractures.
• Propylitic Alteration, which forms the outer periphery of the alteration envelope, is characterised by the predominance of chlorite. Two sub-zones have been recognised, with a gradational common contact, namely the epidote-rich inner sub-zone and an outer sub-zone that contains little or no epidote. Calcite is common in the propylitic zone, occurring as fine flakes disseminated throughout the matrix, as well as in thin veinlets or fracture fillings. Pyrite is sparingly found, occurring as discrete grains and occasional as fracture fillings. Quartz generally occurs as micro-stringers, occasionally interspersed with microcrystalline calcite. Chlorite is commonly found as micro-veinlets or as fracture fillings, whilst epidote occurs either dispersed disseminated within the matrix, interspersed with quartz veinlets or superimposed on the plagioclase.
• Argillic Alteration, which is a minor component of the alteration pattern, overprints the other alteration types, and is apparently limited to the Bacada area, the SE arm of the main deposit, and the area just southeast of Bacada. It is interpreted to represent a late epithermal event, and includes both localised advanced argillic alteration and more extensively distributed intermediate argyllic assemblages. The intermediate argillic zone surrounds and overprints Bacada, and is, in turn, locally overprinted by patches of advanced argillic alteration. The latter is characterised by chalky-white, leached material and strong kaolinite alteration, which occurs as microveinlets, together with fine-grained disseminated pyrite, whilst whitish, 0.3 cm wide quartz veinlets are also evident locally. The clays have been identified as illite and kaolinite, although alunite, characteristic of advanced argillic assemblages, has not been recognised. The argyllised ridges at Lumanggang, immediately to the north, appear to be supergene, tapering downward and persisting no deeper than 5m, whilst the silicified outcrops are strongly leached. Pyrite has not been seen, and the existing pits and vugs indicate that if it was present, it has been completely leached.
• Quartz-dominated Alteration overprints all other alteration zones, and occurs in distinct 140° trending bands within the copper deposit in both the Casagumayan and Tiogdan areas. Here it defines a 800 x 75 m zone, and is interpreted to be related to later epithermal events superimposed upon the porphyry system. This alteration has been divided into two sub-types, namely a:
i). Quartz Stockwork Sub-zone, that is characterised by a network of well-developed, densely interlacing quartz veinlets in which the earlier alteration mineral assemblages, including sulphides, have been, to a large degree, preserved. This stockwork generally carries elevated gold levels, averaging >1.0 g/t Au. At surface, in the Casagumayan and Tiogdan zones, the stockwork forms a steeply NE dipping, 140° trending, 800 x 25 to 140 m band that has been well-exposed by artisanal miners. A more limited stockwork has been outlined in the Lumanggang area, occurring as an irregular, pipe-like 200 x 75 m zone in plan. As at Casagumayan, this zone also contains generally elevated gold values. Microthermometry analysis of samples from quartz stockwork yielded a homogenisation temperature averaging 253°C, well within the epithermal range.
ii). Pervasive silicification, that is texture-destructive, obliterating much of the secondary biotite and preserving only remnants of the feldspars, mafic and original sulphide minerals. It is only found over a restricted area, and is characterised by extreme pervasive quartz replacement to >50 vol.% silica, which appears to have largely destroyed the original copper and gold mineralisation in those rocks that are replaced. It is commonly transitional with the quartz stockwork zone, suggesting that it is an advanced form of the latter. Grades in this sub-zone range from 0.02 to 0.17% Cu total and 0.02 to 0.19 g/t Au.
Mineralisation
Mineralisation within the elongate, dyke-like dioritic intrusive complex at Kink-king is predominantly hosted by the biotite diorite porphyry, followed by intra-mineral hornblende diorite porphyry and intra-mineral diorite porphyry. Within the volcano-sedimentary country rocks, tuffs appear to be the most receptive, particularly adjacent to, or along contacts with the intrusives. Mineralisation occurs as fracture fillings and to a lesser extent as disseminations in the diorite porphyries and adjacent wallrocks. The bulk of the mineralisation is composed of hypogene sulphides. Ibrado, et al. (2013) and Hester, et al. (2010) suggest rapid regional uplift, high rainfall and erosion have removed any leached capping, thick oxide or supergene sulphide enriched zones.
NOTE: The development of such a leached cap and supergene sulphide enrichment would require that since exposure of the hypogene mineralisation, the climate in Mindanao had been significantly drier than at present over a sufficiently long period to form such a profile. In addition, as the host intrusive is a mafic-rich diorite, supergene sulphide enrichment is unlikely, but rather the development of supergene oxides.
The following ore zones are described:
• Oxide Zone, which is up to 150 m thick below the ridge tops, thinning drastically towards the valleys, where it only extend to a depth of a few metres. The transition to sulphides is usually quite abrupt, with the mixed zone seldom being more than a few tens of metres in thickness. The greatest thickness of oxidation is in the Lumanggang zone, the east of the main deposit.
The oxide and mixed oxide-sulphide zones are characterised by partially oxidised chalcopyrite and bornite, with occasional tenorite, malachite, chrysocolla, cuprite and other copper oxide minerals, together with the iron oxides, such as hematite, jarosite and goethite. Malachite and chrysocolla are generally associated with ridge-forming, resistant, highly silicified rocks and quartz stockworks, and as such are over-represented in outcrop. Coarser gold was most abundant in the original soil horizon that has been largely removed by artisanal miners. Gold particles panned along the creeks within the deposit area, typically ranges up to 2 mm in diameter. In general, copper mineralisation in the oxide zone occurs in silicates and phosphates. Copper silicates are the most abundant oxide mineral group present, with those containing MgO and FeO being the most prevalent of this group in the oxide zone.
• Mixed Zone, includes the oxide minerals described immediately above, partially oxidised chalcopyrite and bornite, and limited supergene mineralisation. Hypogene chalcopyrite and bornite are partially to completely replaced by supergene chalcocite and covellite, with covellite almost always rimming bornite. As detailed above, the mixed zone is seldom more than a few tens of metres thick.
• Hypogene Sulphide Zone, which predominantly comprises chalcopyrite with lesser bornite and primary chalcocite, the latter occurring as fracture fillings in the areas of the deposit that are distinctly more bornite-rich. The bornite-rich areas include the biotite diorite porphyry, where bornite partially replaces chalcopyrite and is found in approximately equal, or greater amounts, than chalcopyrite.
Lesser sulphide minerals include molybdenite, which commonly occurs as fracture coatings and in quartz veins. A higher grade molybdenite-bearing shell occurs along the fringes the copper-gold mineralisation. Digenite, covellite, tetrahedrite, galena and sphalerite are found in trace amounts under the microscope.
Gold occurs in a number of forms within the hypogene sulphide zone, including free gold in close association with bornite, and as exsolution intergrowths with other sulphides, particularly chalcopyrite, whilst native gold is occasionally seen on fractures and in quartz veinlets.
The King-king deposit is characteristically pyrite-poor, with <1 vol.% throughout the entire deposit. This is reflected by the relative absence of a pyrite halo surrounding the deposits.
Microthermometry of fluid inclusions in numerous quartz samples from drill core and outcrops indicate high temperatures of homogenization for the mineralising fluids, i.e., >400°, whilst occasional daughter minerals, believed to be halite, have been noted in some samples. These indicate the ore fluids were both high temperature and high salinity. Statistical analysis of 151 homogenisation determinations revealed three thermal populations - the first two with mean temperatures of 848 and 475°C, respectively, and a third population at 253°C. The first two are regarded as typical of porphyry copper systems, whilst the third suggests either an epithermal regime, or possibly mixing with meteoric water, both of which imply emplacement at a shallower depths. These lower temperature samples were mostly from the quartz stockwork outcrops in the gold panning areas and similar stockworks intersected in drill holes.
Resources and Reserves
Mineral Resources, as at 9 August 2011 (Ibrado, et al., 2013) were:
Measured + Indicated Mineral Resource
Oxide Ore - 161.863 Mt @ 0.431% Cu total, 0.266% Cu soluble, 0.535 g/t Au;
Sulphide Ore - 800.389 Mt @ 0.233% Cu total, 0.030% Cu soluble, 0.317 g/t Au;
TOTAL - 962.252 Mt @ 0.254% Cu total, 0.062% Cu soluble, 0.334 g/t Au;
Inferred Resource
Oxide Ore - 33.303 Mt @ 0.276% Cu total, 0.160% Cu soluble, 0.337 g/t Au;
Sulphide Ore - 155.513 Mt @ 0.202% Cu total, 0.024% Cu soluble, 0.249 g/t Au;
TOTAL - 188.816 Mt @ 0.215% Cu total, 0.048% Cu soluble, 0.265 g/t Au;
TOTAL Measured + Indicated + Inferred Resource - 1151.068 Mt @ 0.248% Cu total, 0.060% Cu soluble, 0.323 g/t Au.
Ore Reserves, as viewed on the St. Augustine Gold and Copper Ltd website viewed September, 2024, were:
Proved + Probable Ore Reserve
Heap Leach Ore - 95.164 Mt @ 0.311% Cu total, 0.177% Cu soluble, 0.143 g/t Au;
Oxide Mill Ore - 67.114 Mt @ 0.432% Cu total, 0.281% Cu soluble, 0.779 g/t Au;
Sulphide Mill Ore - 398.657 Mt @ 0.290% Cu total, 0.038% Cu soluble, 0.417 g/t Au;
Low Grade Mill Ore - 56.981 Mt @ 0.190% Cu total, 0.023% Cu soluble, 0.212 g/t Au;
TOTAL - 617.916 Mt @ 0.300% Cu total, 0.084% Cu soluble, 0.395 g/t Au.
NOTE: Resources are inclusive of Reserves
The information in this summary has been drawn from Ibrado, A.S., Hester, M.G., Earnest, D., Aronson, J.G., Roman, R.J., Rehn, C.C. and Harbort, G.J., 2013 - King-king copper-gold project, Preliminary Feasibility Study, Mindanao, Philippines; an NI 43-101 Technical Report prepared for: St. Augustine Gold and Copper Ltd. (TSX:SAU) by M3 Engineering & Technology Corporation, Tucson, AZ, USA., 274p. and
Hester, M.G., Earnest, D.F. and Aronson, J.G., 2010 - King-king copper-gold project, Mindanao, Philippines; an NI 43-101 Technical Report prepared for: Ratel Gold Limited and Russell Mining and Minerals Inc., by Independent Mining Consultants Inc., 288p.
The most recent source geological information used to prepare this decription was dated: 2013.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
King-king
|
We are endeavouring to ascertain why those pages that display Google Maps cannot now do so correctly, and will remedy as soon as practical.
|
|
|
|
Imai, A., Suerte, L.O., and Nishihara, S., 2009 - Origin of Bornite Pods in Intrusive Rocks at the Kingking Porphyry Copper-gold Deposit, Southeastern Mindanao, Philippines: in Resource Geology v.59, pp. 307-313.
|
Suerte, L.O., Nishihara, S., Imai, A., Watanabe, K., Yumul,G.P. and Maglambayan, V.B., 2007 - Occurrences of Ore Minerals and Fluid Inclusion Study on the Kingking Porphyry Copper-Gold Deposit, Eastern Mindanao, Philippines: in Resource Geology v.57, pp. 219-229. doi:10.1111/j.1751-3928.2007.00018.x
|
|
Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
|
Top | Search Again | PGC Home | Terms & Conditions
|
|
