This document discusses using magnetic methods to map iron bodies and anomalies in Aceh Jaya Province, Indonesia. It provides background on manganese mineralogy, the magnetic properties of rocks and minerals, and the earth's magnetic field. The study area is in Babahlo Region, Aceh Jaya Province. Geomagnetic data was collected over several days in July 2011 to measure the total magnetic field and identify anomalies, which could indicate locations of iron deposits for potential exploitation.

1. International Refereed Journal of Engineering and Science (IRJES)
ISSN (Online) 2319-183X, (Print) 2319-1821
Volume 2, Issue 4(April 2013), PP.46-54
www.irjes.com
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Mapping of Iron body or anomaly by using magnetic methods in
Aceh Jaya Province Indonesia
Adi Susilo1
and Walid Mohamed,2
1
Geophysics, Brawijaya University,Malang, Indonesia,
2
Geophysics, Brawijaya University,Malang, Indonesia,
ABSTRACT : In Indonesia, manganese is often found in the shape of sediment mining grain, which is mostly
composed of oxide. It is usually associated with volcanic activity and alkali rock. Manganese may be presented
in the form of minerals such as Pirolusit and Psilomelan, or sometimes in the form of Rhodokrosit, Rhodonit,
Manganit, Brausit, and Nsutit. Manganese reserve of Indonesia is very huge and distributed throughout many
locations. The presence may be in various degrees of small lens shape. The already observed manganese
reserve is 5.35 millions tones, while the mining reserve is 490 thousands tones. The mining is operated by the
private mining company.
Manganese rock exploration is looking for the lateritic form or primary rock. Prospect region shall be
determined before exploration. Nangro Aceh Province is a promising region for exploration due to its geology.
During the exploration and the geological mapping, manganese rock deposit is identified based on the previous
Geological Mapping Report (Rahmat, 2011) which indicates that manganese rock at Babahlo Nangro Aceh
Region (KP Area of PT SURYA TAMBANG PERKASA) is very potential for exploitation.
Keywords : geological mapping, magnetic, Aceh Jaya Province Indonesia
I. INTRODUCTION
Manganese rock at KP of PT SURYA TAMBANG PERKASA, Aceh Jaya, Nangro Aceh Province has
great prospect for exploitation because the result of geological mapping shows that the manganese reserve is
abundant. However, in Aceh Jaya, none manganese rock is exploited for industry, export and domestic interests.
The development of manganese rock resource, hydrogeology, and the access and mining of manganese are not
considered, possibly due to community issue in the prospect region.
The report of manganese rock sediment exploration shall be submitted as the condition of the mining
activity. Exploration activity must consider the result of preliminary study because it gives a more detail
description of the sediment condition of excavated material. The result of this study will determine the reliability
and the prospect of sediment before going toward exploitation stage (the mining process).
Exploration survey against manganese rock deposit may involve geophysic, in this case using
Geomagnet method. This method measures magnetic field variation on the earth surface due to the magnetized
thing below earth surface. The measurement data can inform the physic of rock, the geometry of rock below
surface, and the position of depth. This information will be useful for us to understand the relationship between
the physic nature and observation data. This relationship will always include mathematic equation (mathematic
model). Using this mathematic model, we can obtain the precise information of physic nature below the surface
and the depth position.
II. MINERALOGY OF MAGNESIUM
Worldwide manganese mineral is only 0.1 % of earth crust, but being one of 12 substances with
greatest rate within earth crust. There are more than 300 manganese minerals acknowledged, but only 13
minerals are often found in the commercial grain deposit. The main grains of manganese are Pirolusit and
Psilomelan.
III. MAGNETIC PROPERTIES OF ROCKS.
The magnetic properties describe the behavior of substance under the effect of magnetic field. This
magnetic phenomenon occurs from the electric loaded movement in the substance. There are three groups of
material based on its magnetic properties:
A- DIAMAGNETIC SUBSTANCE.
Electron shell of the substance under the effect of electron magnetic field will rotate and produce magnetization
in the reverse direction against Lenz Law. Rock-forming atoms have paired electron shell. If it obtains magnetic

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field from beyond orbit, the electron will produce low magnetic field to challenge against the outer magnetic
field. This substance has negative and small k susceptibility, and does not depend on outer magnetic field. The
example substances are bismuth, graphite, gypsum, marble, quartz, and salt.
B- PARAMAGNETIC SUBSTANCE.
This substance has less saturated outer most part of electron shell, with not-paired spun electron. If the
outsider magnetic field is presented, the spin is processing to produces magnetic field with parallel direction to
the outside field to strengthen this field. However, magnetic moment is randomly oriented by thermal agitation,
and therefore, its k susceptibility is positive and > 1, and also depending on temperature. The example
substances are manganese, pyroxene, olivine, garnete, biotite, amphybolite and others.
Within magnetic things, the field produced by permanent atomic magnetic moments tends to empower the
outside field, while the field dielectrics from dipoles always challenge against the outside field, whether these
dielectrics have either induced or oriented dipoles. In both cases, the power of induced M (magnetic moment per
unit volume) directly relates with H magnetic field:
where k is magnetic susceptibility, and thus
In general, susceptibility is two-rank tensor. Indeed, k symbolizes "quasi isotropic" of the susceptibility.
Diamagnetic Substance, therefore, has negative susceptibility. This measure is suitable for the rock which makes
up the mineral (Tarling and Hrouda, 1993). Diamagnetic susceptibility does not depend on temperature. The
dependability on temperature of paramagnetic susceptibility is explained by Curie Law or Curie-Weiss Law.
C- FERROMAGNETIC SUBSTANCE .
Many electron shells are only filled by one electron, and therefore, the shell is easily induced by the
outside field. The inducement is further supported by the presence of parallel spun groups with establishing
magnetic dipoles (domain) with similar direction, especially in the outside magnetic field. Its k susceptibility is
positive and >> 1, and depending on temperature. The example substances are iron, nickel and cobalt.
D- Anti-Ferromagnetic.
Some domains are producing magnetic dipole with reverse direction such that whole magnetic moment
is very small. Anti-ferromagnetic material has crystal defect, small magnetic field, and small susceptibility. Its
susceptibility may be similar to paramagnetic field but the price of anti-ferromagnetic will increase until Curie
point but decrease again based on Curie-Weiss Law. The example substance is hematite (Fe2O3).
E- Ferrimagnetic
Some domains are anti-parallel but the number of dipole in each direction is not similar. Therefore, it
has relatively huge magnetization resultant. The susceptibility is high depending on temperature. The example
substances are magnetite (Fe3O4), ilmenite (FeTiO3), and pirhotite (FeS).
IV. Magnetic Properties of Mineral.
Mineral is also classified as:
a. Diamagnetic Mineral
b. Paramagnetic Mineral
c. Ferromagnetic Mineral
d. Ferrimagnetic Mineral
e. Anti-ferromagnetic Mineral
a) Diamagnetic Mineral and Paramagnetic Mineral
Because of the presence of non-stoichiometry-Fe or Mn-ion (Manganese), some minerals are
paramagnetic (Petersen, 1985). Some degrees of these minerals are shown by Dortman (1976) as positive and
relatively higher, and thus, it is assumed that the sample observed has dirt (Fe, Ti) which produces positive
superimposed component.

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Figure 1 The Table of Susceptibility Rate of Paramagnetic Mineral (Dortman, 1976).
Figure 1. Order tectonic and sedimentary basins in Kalimantan.
Iron (Rao and Bhimasnkaram, 1960)

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Figure 2. The Table of Susceptibility Rate of Manganese Mineral Associated with Iron (Rao and
Bhimasnkaram, 1960).
b- Ferro-, Antiferro-, and Ferromagnetic Minerals
The most important mineral which is abundant in the ferromagnetic rocks is titanium oxide. Iron, iron
oxyhydroxide and iron sulfide are also presented but not abundant (Beil and Petersen, 1982).
Fe-Ti-oxide is "substance" dominated magnet, and it is a magnetic rock which is particularly presented in Terner
System.FeO (wustite) - Fe2O3 (hematit, maghemite) - TiO2 (Rutile)
This system provides “the most fundamental knowledge about the characteristic of general
ferromagnetic rocks” (Nagata, 1966). Terner System contains chemical compositions such as:
● Mineral oxide in the rock magnetism (Nagata, 1961): FeO (wustite), Fe3O4 (magnetite), γ-Fe2O3
(maghemite), α-Fe2O3 (hematite), FeTiO3 (ilmenite), Fe2TiO4 (ulvospinel), Fe2TiO5 (pseudobrookite) and
FeTi2O5 (ilmeno-rutil, ferropseudobrookite); and
● Four-series (solid solution serial), including titanomagnetit, ilmeno-hematit, pseudobrookite, and
titanomaghemite.
Below is the elaboration of some relevant parameters.
Figure 3.. The Terner System of Rock Ferromagnetic Characteristic (Nagata, 1966).
Serial titanomaghemite: its structure of cubic / inverse spinal. This serial has final member of magnet,
ulvospinel, which has equation of Fe3-X TixO4 with 0 ≤ x ≤ 1. It is characterized by saturated magnetization,
early susceptibility, and reduction Currie-temperature with increased x, as shown as follows (Bleil and Petersen,
1982):

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Tc = 851 - 580x-150x2
In relative with titanomagnetitues abundance, Bleil and Petersen (1982) explain that: "titanomagnetities ... ... is
the most common magnetic mineral in the rocks.... Magnetite aggregate may occur in some kinds of rocks such
as frozen rock, metamorph, and sediment. This aggregate is found in certain meteorite, but not observed in the
moon sample. Usually, it is produced from various subsolidous reactions. Due to its magnetism on rocks, Serial
Ilmenite-hematite: the structure is hexagonal/rombohedral. This serial has final member of ilmenite and
hematite, and the formula is
Fe2-x TixO4 with 0 ≤ x ≤ 1
For the detail of complex relationship between the characteristic and composition, see Bleil and Petersen (1982).
The serial produces natural characteristic orientation. Hematite is the carrier of remanent magnetization is the
sediment (mainly in the specular grain and pigment). In the frozen rock, the main composition of serial is
chemical properties of the rock. Due to the reduction of alkalinity,
ilmenit is reduced, but subsolidus reaction increases ilmenite. This serial is also found in various metamorph
rocks.
Serial Pseudobrookite: The structure is ortorombik. The serial is defined by the final member of
Pseudobrookite Fe2TiO5 and FeTi2O5 ferroPseudobrookite. At room temperature, Pseudobrookites is
obviously paramagnetic (Bleil and Petersen 1982). It is found in the natural occurrence of frozen and
metamorph rocks.
Serial Titanomaghemite: The structure is spinal. Titanimaghemite is produced by oxidation of
titanomagneties at 300°C (Petersen, 1985) with +. change on Fe2 + Fe3. In maghemite, one member and other
are shown by formulation (Fe, Ti, δ) 3O4, where δ shows that the emptiness is variable at metal ion sites in
crystal structure. The magnetic properties are controlled by the composition and affected by “ratio of oxidation”,
Fe2O3 / (Fe2O3 + FeO). The ratio of oxidation to Currie temperature is increased. Titanonaghemite is the main
magnet constituent in the basaltic sea basement, but it is also found in the continent frozen rock (Bleol and
Peterson 1982). Pyrrotite FeS1-x is a representative from iron sulfide (monoclinier and hexagonal) with
ferrimagnetik behavior. The representative of iron oxyhydroxides α gutit-FeOOH and lepidocrocite γ-FeOOH
are ortorombic.
V. Earth Magnetic Field
Earth magnetic field is characterized by physic parameters, which are also called as the element of
earth magnetic field (Figure 1). These are measured by direction and intensity of magnetization.
These physic parameters are:
a. Declination (D), which is the angle between magnetic north and horizontal component, as
counted from north toward east.
b. Inclination (I), which is the angle between total magnetic field and horizontal plane, counted
from horizontal plane toward vertical plane at the below.
c. Horizontal Intensity (H), which is the rate of total magnetic field on the horizontal plane.
d. Total Magnetic Field (F), which is the rate of total magnetic field vector.

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Figure 4. There Elements of Earth Magnetic Field
Main magnetic field in the earth is changing with time. To keep the uniformity of earth magnetic field values,
the standard is made, which is called International Geomagnetics Reference Field (IGRF), which is revised once
in 5 years. IGRF values are obtained from the measurement of the average of width coverage of 1 million km2
in the one year period.
Earth magnetic field comprises to three parts:
1-Main magnetic field (main field)
Main magnetic field is defined as the average field which is the result of measurement at long term and covering
the width more than 106 km2.
2- Outside magnetic field (external field)
The effect of outside magnetic field may come from the outside the earth, and it represents the result of
ionization in the atmosphere caused by ultraviolet beam from the sun. This external field source associates with
the electric current flown in the ionized layer at atmosphere, and thus, the field change is accelerated with time.
3-Anomaly magnetic field (main field)
Anomaly magnetic field is also called as local magnetic field (crustal field). This magnetic field is produced by
rocks composed of magnetized mineral such as magnetite ( 87 SFe ), titanomagnetite ( 42 OTF ie ) and others in
the earth crust
In the survey on magnetic method, the target of measurement is the variation of magnetic field measured on the
surface (magnetic anomaly). In general, magnetic field anomaly is caused by remanent magnetic field and
induced magnetic field. The remanent magnetic field plays great role in the rocks magnetization because it
determines the rate and direction of magnetic field. However, it always associates with previous magnetic event
such that it is complex for observation. Anomaly found in survey is the result of mixture of ermanent and
induced magnetic fields. If the direction of remanent magnetic field is parallel with induced magnetic field, the
anomaly is greater, and so is the reverse. In the magnetic survey, the effect of remanent field is negligible, if
magnetic field anomaly is less than 25 % of main magnetic field of earth (Telford, 1976), such that the
measurement of magnetic field is as follows
ALMT HHHH


where : TH

: total magnetic field of the earth
MH

: main magnetic field of the earth
LH

: external magnetic field
AH

: anomaly magnetic field .

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VI. Conclusion and Results
The measurement of geomagnetic data is conducted by surevy team from University of Brawijaya Malang, East
Java, from 15-21 July of 201 at Babahlo Region, IE Jeureungeh Region, Sampoinet Subdistrict, Aceh Jaya
District, Nangro Aceh Darussalam Province. The location of survey is at the following coordinates:
POINT LONGITUDE (EAST) LATITUDE (NORTH/SOUTH)
A 95o
30'49.74'' 4o
56'59.26''
B 95o
31'12.53'' 4o
56'59.26''
C 95o
31'12.53'' 4o
56'13.30''
D 95o
30'49.76'' 4o
56'13.30''
AREA WIDTH: 100 Ha
Table 1. The Coordinate Points of The Location of KP.Exploration of PT. Surya Tambang Perkasa
Figure 4.1. The Survey Location Map at Babahlo Region, IE Jeureungeh Region, Aceh Jaya District
Figure .2. The Survey Location Map at Babahlo Region in 3D

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Data are collected using Magnetometer Device, in the Proton Precision Magnetometer (PPM). Data collection
spread includes 1624 data collecting points, as shown in Figure 4.3 as follows.
Figure 4.3. The geomagnetic data collecting points which are correlated with the contour of magnetic value
spread at survey location.
The result of data measurement correlated with topographic contour at Babahlo region is shown in Figure 4.4
and 4.5.
Figure 4.4. Topography Contour Map which is overlaid with magnetic value spread from the result of
measurement at survey location in 2D.

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Figure 4.5. Topography Contour Map which is overlaid with magnetic value spread from the result of
measurement at survey location in 2D.
Figure 5. Topography Contour Map which is overlaid with magnetic value spread from the result of
measurement at survey location in 2D.
ACKNOWLEDGEMENTS
First of all, many thanks to my big family (My mother, my Father, my sisters, my brothers Mostfa,
ali,almhde) for their prayer, patience and invaluable support during my long lasting study in a distant country.
I would like to say thanks to our Lord Allah Subhanahu wa Ta’ala and to the Messenger Zoher alhdad peace be
upon him that guide me to the beautiful path in my live. I dedicated all of my life and work to them totally
Second My special thanks to Adi Susilo, PhD for providing me with the opportunity to work on this paper. I
also appreciated their guidance, encouragement to make this paper, spending extensive time in the field during
data processing, and always being available to discuss interpretation of the data. I would like to thank, Dr. Eng.
Didik R., for reviewing this paper. Their suggestion improved significantly this manuscript.
Finally I would like say thank to all of my friends: Mr. Ramdahan, Mr. Abdulrazak et al. And also my friend
Nabil in Libya , thank you so much for your friendship.
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