Geological Characterization of the Infanta Nickel
Laterite Deposit, Brooke’s
Point, Palawan
Rufo S.
Cabanlig, Jr. 1, Omar Teogenes A. Alfonso2,
Rikki Pamela L. Pineda1, Marvin M. Ubaldo1,
Brenda C. Jumangit1, Godfrey E. Atienza1 and
Jane Kristine A. Teves1
1MacroAsia Corporation, 12/F, Allied Bank Center, 6754 Ayala Avenue,
Makati City
2
MacroAsia Corporation, Infanta Nickel Project, Bgy. Ipilan, Brooke’s
Point, Palawan
Abstract
The
Infanta Nickel Laterite Deposit in Ipilan, Brooke’s Point,
Palawan was discovered in the early 1970’s and later mined by
Infanta Mineral and Industrial Corporation (IMIC) in 1977 to 1978.
The IMIC’s name was later changed to MacroAsia Corporation
(MAC) in 1995. MAC entered into a Mineral Production and Sharing
Agreement (MPSA No. 220-2005-IVB) with the Republic of the
Philippines in December 2005. The UP Geoscience Foundation, Inc.
(GSF) was commissioned to do a preliminary assessment of the area in
August of 2006 and the first phase of Geological and Resource
Evaluation of the prospect was completed in March 2007. Subsequently,
four additional core drilling and two test pitting campaigns were
undertaken.
Similar
to other nickel laterite deposits in South Palawan, the area is
underlain by the Palawan Ophiolite which is comprised of an
ultramafic complex, gabbro, pillow basalts and its sedimentary
carapace. The ultramafic complex consists of lherzolites,
harzburgites, dunites, pyroxenites and peridotites. These
ultramafics, with lherzolites being dominant in the area, serve as
parent materials of the laterite deposit. Serpentinization plays a
major role as evidenced by the presence of serpentine, talc and
chlorite in core samples and under the microscope. Silicification is
also apparent as boxworks formed along fractures. Also associated
with the presence of silica are garnierite which appear as its
coating material. Minor occurrences of metamorphics, dunite and
basalt have also been observed. Weathered schists present in the
western portion of the tenement are the favored upland farmlots of
the kaingineros.
Core samples were obtained and assayed to determine its mineral
composition. Chemical analyses identified a 14-mineral suite. Among
the metals and minerals identified are Ni, Co, Fe and MgO. Limonite
yielded Ni values of < 1% to about 1.64%. In most of the samples,
Ni content increased in the saprolite layer with values in the range
of < 0.5% to as high as 2.72%. Average for both limonite and
saprolite layers combined is about <0.5% to 1.72%. Cobalt, on
the other hand, displayed decreasing values from limonite (0.04 -
0.25%) to saprolite (<0.05 to 0.27%). The average values for the
limonite-saprolite layers are from <0.05 to 0.27%. Iron also
exhibited decreasing values of >20 - 48.18% in the limonite layer
to <10 - 48.95% in the saprolite layer. Average values for both
limonite-saprolite range from 15.20 - 41.11%. MgO concentrations show
an increasing trend from limonite (>0.80 – 17.60%) to
saprolite (>3.0 – 36.52%) while average values range from
1.39
Laterite thickness range from about 2 meters to 37.4 meters with an
average of about 15.18 meters. Thickness of limonite ranges from 0.6
to 24 meters. Limonite is generally thicker than saprolite which is
0.4 to 20 meters in thickness.
Relationship between Ni-enrichment and rock type is inferred. Another
factor is the degree of serpentinization which may influence the
leaching process and subsequent metal accumulation. On the other
hand, factors which may have dictated laterite formation and
thickness are topography, climate, rock mineralogy, geologic
structures and time. These are discussed in relation to the extent at
which the deposit in the area has developed.
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