Placer Mine


Placer mineral district is dominated by at least three - major arc parallel, NNE trending fault zone. The east most zone cuts across Timamana, Makalaya, Amoslog, East of Legaspi-Varona dilational jog and goes out of the sea in the Placer town site. The middle zone traverses Anislagan, Tres de Mayo, Bad-as, Iglesia ni Cristo clay-pyrite zone, Mindoro-Ntina and out in Alipao. The westmost zone is defined by Bagacay, Sta Cruz, Suyoc, Reno-Emma-Irene Didjo Areas and out into the Banbam coastal area. The major deposits are related, confined and controlled by intersections of NNW to NNE compression structures whose interaction yielded high angle ENE to EW tension fractures and dilatational jogs.

North and Northeast trending fold axes are discernable within the Bacuag Formation and Mabuhay Formation related rocks. NNW and NE to E-W thrust faults are known to occur along contacts of younger limestone and Bacuag Fm. and also between tuff/breccias and andesite porphyry, e.g. Nellie, Heine and Emma deposits of MMC.

At MMC's Placer Project, lineaments and faults trending NNW are generally considered as first-order structures and those that trend NNE and NE are second-order structures. The primary compressive stress is interpreted to be directed toward the west, which is related to the direction of subducting plate

Notes on Occurrences of Economic Significant Au-Cu Mineralization in Placer Mineral District
  1. Irene-Didjo: A 50m x 200m area of small-scale gold mining along NE trending faults located at the northwest rim of the Briggs pyroclastics. Mineralization consists of quartz-limonite-pyrite stockworks, 2-15 cm moderately dipping sheeted veins and 3-8m silicified fault breccias. Most of the mineralization is in the fault breccias that persist to a strike length of 200m. Gold grades range from 0.60 g/t Au to 15.0 g/t Au.
  2. Reno-Emma: 1-2m wide, fissure quartz veins in andesite porphyry developing into 10m wide stockwork zones in overlying Briggs pyroclastics. Individual veins have gold values of 3-4 g/t Au, while stockwork zones average 1-2 g/t Au. The quartz texture is chalcedonic and vuggy. Occasional associated base metal sulfides are sphalerite, galena and chalcopyrite. Ore shoots are sited on dilatant portions of steeply dipping NE shears.
  3. Briggs-Colorado-Heine: Fault controlled quartz vein-stockwork-replacement epithermal gold mineralization hosted in andesitic diatreme vent and apron breccias, with subordinate stratiform fill-replacement deposits in sandstone, siltstone and limestone-diatreme slide blocks. Bulk of the gold mineralization occurs in quartz micro-stockworked and silica replaced vuggy diatreme breccias, having gold grades of 1-3 g/t Au. Ore material is peppered with fine hematite, giving it a dark bluish gray color. High-grade (10-300 g/t Au) drussy coarse grained to chalcedonic quartz veins fill fault feeder structures and permeable bedding structures. <1% pyrite is widespread in the deposit, with occasional specks to clumps of sphalerite, galena and chalcopyrite in the vein materials. Some stibnite is found associated with chalcedony in the upper sections of the fault veins and in the flat lying "opal zones". The stibnite bearing chalcedony has assayed to as high as 3000 g/t Au.
  4. Bull Vein-Mindoro: Contiguous vein stockwork epithermal gold mineralization hosted in Mabuhay Clastics (tuff- tuff breccia) and andesite porphyry and controlled by NE, ENE, and WNW fault zones. Elevated gold occurrences are associated with late stage drussy; clear to milky white to amethystine quartz veins/veinlets and hydrothermal breccia fills that terminate at central vugs into small hexagonal quartz crystals, silica crusts, and silica psuedomorphed carbonate rhombs. The quartz veins/veinlets occasionally contain sphalerite and galena in addition to pyrite. Wall rocks are altered to clay and sericite and are highly pyritized. Mineralization overprints earlier porphyry Cu style stockwork mineralization characterized by pyrite-hematite/ magnetite -chalcopyrite -molybdenite mineral assemblage.
  5. Suyoc: Small porphyry copper deposit hosted in fine grained andesitic intrusive and tuff breccias and localized on intersection of major NE and NW shears. The core of the ore zone is characterized by quartz-pyrite-chalcopyrite-magnetite stock-workings. The Suyoc porphyry copper deposit is overprinted by the NE structure controlled Kinto Limbo vein-stockwork epithermal gold mineralization.
  6. Mapaso: Epithermal gold deposits defined by a 100m-300m wide zone composed of a series of sub-parallel ENE faults cutting through mostly Bird's Eye Porphyry. The zone has a mapped strike length of 1.50km. Alteration within the zone is predominantly argillic with silicification and/or quartz veining limited to fault structures and hydrothermal breccias. Elevated gold values are associated with vuggy, milky white to gray pyritized quartz veins/veinlets and hydrothermal breccia fills and the presence of sphalerite and/or galena.
  7. Boyongan: Porphyry copper deposit recently discovered by Anglo-Philex, hosted by a composite diorite porphyry stock containing at least seven distinct phases of intrusions-brecciation. Alteration consists of pervasive K-silicate with weakly developed intermediate argillic overprint and localized advanced argillic lithocap that has been unroofed by erosion. Copper-gold mineralization is associated with dense quartz stockworking. Deep supergene oxidation has affected portion of the Boyongan porphyry deposit. The oxidized zone, up to 600m thick, is characterized by an abundance of cuprite, azurite, malachite, chrysocolla, neotocite, and native copper. Hypogene sulfides include chalcopyrite and local bornite.
  8. Kalaya-An (Bayugo) Gold Copper Prospect - A bulk-mineable, low sulphidation epithermal stockwork Au target, with the upside of finding high-grade bonanza vein feeder structures. At depth, this epithermal mineralization overprints an earlier porphyry copper 'style' deposit.

Mineral Occurrences and Potential Exploration Targets

Within the Immediate Vicinity of Active and Suspended Mining Pits

1. Epithermal Gold Targets

Vein-stockwork, low Sulphidation, epithermal gold deposits are more widespread and voluminous in the Placer mines. The most productive of these deposits are Heine-Briggs-Colorado and New Tinupan-Bull Vein-Mindoro. Lesser deposits were also mined at Reno, Varona and Legaspi. Elevated gold occurrences in these epithermal deposits are associated with drussy fine crystalline to chalcedonic quartz veins/veinlets that contain occasional galena and sphalerite and rare stibnite. Low temperature boiling textures such as quartz needles, silica crusts, and silica psuedomorphed carbonate rhombs are common. Wall rock alteration is dominated by silica and illitic clay.

Discovery of additional epithermal gold deposits is possible in the short term (within six months to 2 years). This entails a sound understanding of the geology, alteration and structure of the mine area. Targets areas may be inferred by reviewing existing geologic maps and both hard copies and digital copies of geological, geochemical and geophysical database. Selection of quality drilling targets requires sound ground-truthing of structures and important geological units such as diatreme. Arcuate diatreme or breccia pipe contacts may localize gold mineralization (e.g. Wafi, PNG or Kidston, Queensland, BCI's Balatoc Diatreme (???) although gold may be localized in quartz veins along structures which cross-cut the diatreme (Kelian, Indonesia) or which flanks porphyry coppers (Victoria, Lepanto) Detailed structural and geological mapping is essential. Furthermore, epithermal gold systems show vertical and lateral zonation of their alteration and mineralization, and the zonation is best understood by examination of drill cores and comparing adjacent drill holes.

2. Porphyry Copper Targets

Small and low-grade deposits of porphyry copper are present in the Placer mines at Bull Vein, Mindoro West and Suyoc. At Bull vein and Mindoro West, the porphyry mineralization is characterized by veinlets of chalcopyrite +pyrite ±molybdenite ±magnetite ±hematite with or without quartz in clay-chlorite-sericite altered basaltic to andesitic flows and clastics. At Suyoc, it is characterized by chalcopyrite +pyrite veinlets with quartz in silica-clay-sericite altered fine-grained porphyry. These porphyry copper deposits are overprinted by later epithermal gold mineralization.

Areas outside mining pits
Outside of the Norsumico & Magsaysay claim groups and within the MMC MPSA-APSA 0006-X / TEP XIII-003-2000 / EP-XIII-014 are several ready to drill as well as grass root exploration targets. The first and foremost is the Makalaya-Anislagan Au-Cu prospect (Kalaya_An Project) expected as a bulk-mineable, low sulphidation epithermal stockwork Au target, with high-grade bonanza vein feeder structures. At depth, this epithermal mineralization overprints an earlier porphyry copper 'style' deposit. Potential resource, based on the size of alteration, extent of geophysical anomaly and structural-geological setting, indicate that Kalaya_an is comparable or even better than Anglo-Philex's Boyongan Porphyry Au-Copper Deposit where over 100 M tonnes of Oxide porphyry Au-Cu has been fenced drilled. Having appreciated the limited size of Boyongan, Anglo-Philex drilled very close to the Anglo-Philex / MMC Kalaya_an EP Area boundary. Furthermore, Anglo-Philex had drilled the Bagacay prospect, sited immediately north of MMC's Kalaya_an project.

3. Mesel Style Sediment Hosted Replacement

Possible Mesel Style Mineralization Located within the Tres de Mayo Area, SW of Legaspi, characterized by the following encouraging parameters.

  1. Floats of jasperoidal limestone disclosed along creeks and gullies draining the Tres de Mayo area. A handful of these floats have been collected for Au, Cu, As, Sb, Ag, Pb, Zn and Mo metal content analysis. The first two elements are now being assayed in MMC assay laboratory with gold using MIBK. The succeeding suite of elements is being coordinated with Lepanto Mine's assay laboratory in Mankayan.
  2. Good structural address being centrally located at the intersection on the ENE trending Legaspi - Varona Veins and NNE trending shears dominant within the MMC mining district.
  3. Stratigraphically, an extensive (2 km by 3 km)- massive reefal limestone body of adequate thickness (50- 100 m. thick), intruded by dikes and stock of bird's eye andesite porphyry.

This particular area is adjudged to be prospective for having a stratigraphic-structural and geochemical setting similar to the Mesel Mine of Newmont Minahasa Raya, a 1.7 M oz. Au mine located in Ratatotok district in the Kabupaten of Minahasa, North Sulawesi Indonesia.

4. Sweat Quartz-Metamorphic Quartz

Apparently, the Cu-Au veinlet mineralization in the SE portion of NTINA is not related to SCC altered (porphyry copper style) basaltic to andesitic volcaniclastics but rather related to sweat quartz-base metal sulfide (Cpy, py, mag, mo, gal, sph) -gold mineralization attributable to regional metamorphism and thrusting. This gold occurrence is akin to oregenic lode - low sulphide gold-quartz veins e.g. Mother lode in California, USA and the Penjom mine in Malaysia. The veins are characteristically very dry i.e. no alteration selvage as there is very little water-rock interaction. However gold and base metal content of the veins can be very significant (15-30 gpt Au).

5. Other Areas

Grass root targets within MMC's EP Application are as follows.
  1. Potential block faulted extension of Suyoc porphyry Cu mineralization as indicated by a ground geophysical survey at Bugas-Bugas.
  2. Possible sediment hosted gold as well as "Siana-SURICON Style" mineralization in Tagbungabong located on the eastern side of the Exploration permit area.
  3. Potential Heine and NTINA style mineralization as well as sediment-hosted gold mineralization - Carlin/Mesel Style in Magupange sited on the northwestern side of the EP area.

Geology and Mineral Characteristics of Manila Mining's Placer Mine
Volcanic, Volcaniclastic & Sedimentary Rocks
Intrusive Rocks

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Geology and Mineral Characteristics of Manila Mining's Placer Mine
Volcanic, Volcaniclastic & Sedimentary Rocks Intrusive Rocks
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