1. A SEMINAR TITLED:
TALC MINERALIZATION IN NIGERIA; GEOLOGIC &
PETROGRAPHIC VARIETIES.
BY
OLABISI, OLAMIDE OLUWATOBI
110812037
DEPARTMENT OF GEOSCIENCES (GEOLOGY)
SUPERVISOR: PROF S. B. OLOBANIYI

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ACKNOWLEDGEMENT
I give thanks to the Almighty who has been the source of my wisdom,
strength and guidance in the course of writing this seminar.
I also appreciate my supervisor, Prof S. B. Olobaniyi for his counsel and
time.
Worthy of sincere appreciation are my parents, who have been with me
through time and for providing me with the various resources to carry out this
work. And also, I hereby appreciate my dear colleagues.
Thank you and God bless you all.

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LIST OF FIGURES
Figure 1. Geological sketch map of Nigeria showing the major geological
components;Basement, Younger Granites, and Sedimentary Basins 6
Figure 2. Schist belt localities within the context of the Geology of Nigeria 8
Figure 3. Comparison between Talc and Quartz 11
Figure 4. Demonstrating the hardness test of talc 12
Figure 5. Illustration of Talc depositin Dolomite 13
Figure 6. A miner in a dolomite & talc mine 14

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ABSTRACT
Talc deposits result from the transformation of existing rocks via hydrothermal
activity. Through this process, the components (MgO, SiO2, and H2O) required for
transforming the parent rock into talc are brought by hydrothermal water. The size
and the geometry of the final deposit depend upon the size and nature of the parent
rock, the intensity and scale of the phenomenon. The geological conditions
required for such a transformation to occur are low to medium temperature and
pressure metamorphism.
In Nigeria, talc deposits are found within the Schist belts in the Basement Complex
which is one of the major geological units that comprises the geology of Nigeria.
Hence, it occurs in areas such as Wonu, Iseyin, Ilesha and Isanlu.
The talc deposits in Nigeria have been observed to be characterized by marked
variety of mineralization and petrographic properties. Nonetheless, talc still
remains a mineral that possesses high demand in the industry due to its wide areas
of application, as it used in the manufacturing of various products such as;
cosmetics, paints, textile, etc.
KEYWORDS: Talc, Mineralization, Geologic, Petrographic, Varieties, Nigeria.

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TABLE OF CONTENT
Title Page 1
Acknowledgement 2
List of figures 3
Abstract 4
Table of Content 5
Chapter One: Introduction 6
1.1 Brief Overview of the Geology of Nigeria 6
1.2 The Mineral Talc 7
Chapter Two:Mineralogyof Talc 10
2.1 Chemical Properties of Talc 10
2.2 Physical Properties of Talc 10
Chapter Three: GeologicVarieties & Occurrence
3.1 Formation & Deposit of Talc 13
3.2 Case Studies in Nigeria 16
Chapter Four: Petrographic Varieties 19
Chapter Five: Conclusion 21
References 22

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CHAPTER ONE
INTRODUCTION
1.1 Brief Overview of the Geology of Nigeria
The geology of Nigeria is described by three major litho-petrological units,
which are the BasementComplex, YoungerGranites and the Sedimentarybasins
(Figure 1). The basement complex, which is further divided into the following
units; the Migmatite-Gneiss Complex, the Schists Belt, the Older Granites and
the Undeformed acid and basic dykes, houses most of the solid mineral deposits
in the country (Obaje, 2009).
Figure 1. Geological sketch map of Nigeria showing the major geological components;
Basement, Younger Granites, and Sedimentary Basins (Obaje, 2009)

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Mafic-ultramafic rocks are most prominently found within the Schist belts
(Figure 2) of Southwestern Nigeria as lenticular and ovoid bodies of amphibolite
and meta-ultramafites (Elueze, 1982). The Schist belts which are probably of
middle to upper Proterozoic age, comprise dominantly low-medium grade
metasediments, and occur in basement of mainly older gneisses and migmatites.
They are said to be confined to the western part of the country, west of 8◦E
longitude (Turner, 1983). However, Rahaman (1981) assert that similar suites are
present within the Oban massif in the South-East. The belts are confined to a NNE
trending zone of about 300 km wide.
The schist belts have been mapped and studied in detail in the following
localities: Maru, Anka, Zuru, Kazaure, Kusheriki, Zungeru, Kushaka, Isheyin
Oyan, Iwo, and Ilesha where they are known to be generally associated with gold
mineralization (Obaje, 2009).
1.2 The Mineral Talc
Talc is a platy mineral belonging to the group of silicates. It is formed either
through regional or contact metamorphosis of carbonate sediments or through
hydrothermal alteration of magnesium-rich magmatic rocks. Ideally, all rocks
containing talc are metamorphic rocks and talc is thus present as a secondary
mineral (Mondo Minerals).
It is also called steatite or, in chemical terms, hydrated magnesium silicate.
It is the main component of soapstone. Accompanying minerals include magnesite,
dolomite, chlorite, serpentine, calcite, chlorite, and in some cases sulphides, quartz,
tremolite or vermiculite.

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Several types of talc deposits may be distinguished according to the present
composition and parent rock from which they are derived. The talc deposits in
Nigeria are associated with the amphibolites of the schist belts (Elueze, 1982).
They generally belong to the group of important non-metallic mineral resources
that are consumed in several industries. Magnesian minerals notably talc,
Mg3Si4O10(OH)2 are substantial constituents of some of the mafic-ultramafic rock
units in Nigeria.
Figure 2. Schist belt localities within the context of the Geology of Nigeria (After Woakes et
al 1987)

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Talc is majorly applied in the cosmetic, refractory, ceramic and textile
industries. It is a principal raw material in the manufacture of powder, paint, soap,
paper, rubber, insecticide, pharmaceuticals, cosmetics and roofing. The versatility
of talc as an industrial mineral has resulted in its dire need for industrial purposes.
It has become imperative that rocks forming talc be mineralize to meet its demand
in industries.

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CHAPTER TWO
MINERALOGY OF TALC
2.1 Chemical Properties of Talc
Although the composition of talc usually stays close to the generalized
formula above, however, some substitution occurs. Small amounts of Al or Ti can
substitute for Si; small amounts of Fe, Mn and Al can substitute for Mg; and, very
small amounts of Ca can substitute for Mg. When large amounts of Fe substitute
for Mg the mineral is known as minnesotaite. When large amounts of Al substitute
for Mg the mineral is known as pyrophyllite.
Talc has a high capacity for absorbing organic substances, the opposite
applies to water; talc is hydrophobic and insoluble. It is also acid-resistant,
chemically inert and non-toxic. Its resistance to heat, electricity and acids make it
useful for lab counter tops and electrical switchboards. It is an important filler in
paints, rubber and insecticides.
Talc often replaces other minerals atom by atom to form pseudomorphs, taking the
form of the replaced mineral. Thus, a specimen of what appears to be
milky quartz would actually be talc (Figure 3).
2.2 Physical Properties of Talc
Talc is usually green, white, gray, brown or colourless. It is a translucent
mineral with a pearly luster. It is the softest known mineral (Figure 4) and hence
assigned a hardness of 1 on Mohs hardness scale (Geology.com).

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It is a monoclinic mineral with a sheet structure similar to the micas. Talc
has perfect cleavage that follows planes between the weakly bonded sheets. These
sheets are held together only by van der Waals bonds which allows them to slip
past one another easily. This characteristic is responsible for talc’s extreme
softness, its greasy, soapy feel and its value as a high temperature lubricant
(Geology.com).
Talc occurs as foliated to fibrous masses, and in an exceptionally
rare crystal form. It has a perfect basal cleavage, and the folia are non-elastic,
although slightly flexible. As such, it can be easily scratched by a fingernail. It is
also sectile (i.e. can be cut with a knife). It has a specific gravity of 2.5–2.8 g/cc.
Talc is not soluble in water, but it is slightly soluble in dilute mineral acids. It is an
odourless mineral, with a scaly texture.
Figure 3. Comparison between Talc and Quartz

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Figure 4. Demonstrating the hardness test of talc

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CHAPTER THREE
GEOLOGIC VARIETIES AND OCCURRENCE
3.1 Formation & Deposit of Talc
Talc can be formed in different geological environments or processes. There
are various processes involved in the deposition of talc deposits are described
below;
1. Talc derived from magnesium-rich carbonate rocks.
Figure 5. Illustration of Talc deposit in Dolomite.
More than half of world production comes from this kind of deposit, found
in ancient metamorphosed carbonate sequences. This talc is generally pure and
white.

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The talc is formed by the alteration of sedimentary magnesium carbonate
rocks (dolomite and magnesite) at elevated temperature and pressure below the
Earth's surface (Figure 5). While the magnesium is fixed insitu, the silica is
transported by silica-containing hot fluids to react with the Magnesium-bearing
carbonates to form talc. These altered rocks are then talc-rich dolomites or
magnesites. This type of deposits usually delivers the massive talc (Figure 6)
accompanied by carbonates, chlorite and some quartz. The mineral composition is
generally 30 - 100% talc, 0 - 70% chlorite/carbonates and 0.1 - 0.5% quartz.
Figure 6. A miner in a dolomite & talc mine.
2. Talc derived from serpentine.
This type of deposit provides about 20% of the world’s talc. Here, the crude
ore is always grey but can be upgraded - generally using floatation techniques - to
improve mineralogy and whiteness. This type of Talc formation occurred when

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heat and chemically active fluids altered rocks such as dunite and serpentinite into
talc.
3. Talc from alumino-silicate rocks.
About 10% of world production comes from these deposits. They are
sometimes found in combination with magnesium carbonate deposits. The crude
ore is generally grey due to the presence of chlorite (another phyllosilicate), but no
up-grading is generally necessary as chlorite, like talc, is a functional mineral
conferring benefits to a number of industrial applications.
In this case, talc is stable under high-pressure conditions up to a temperature
of about 700°C in association with phengite, Mg-garnet, Mg-chloritoid and
kyanite in metapelites (Al-rich metamorphic rocks). The deposits are often found
in combination with magnesium carbonate deposits. As fourth type, talc may be
formed by direct transformation of magnesium clays. Due to the impurities
associated with the talc ore, no such deposits are currently being mined.
4. Talc from magnesium-rich sedimentary rocks.
Talc is formed by direct transformation of magnesium clays. No deposits
belonging to this category are currently being mined.
This wide diversity of origin and types naturally gives rise to a wide variety
of ores and product grades, which differ according to their mineralogical
composition, colour and crystalline structure (micro-crystalline or lamellar).

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3.2 Case Studies of Talc Mineralization in Nigeria
The meta-ultramafites in Nigeria are of variable minerology and texture. Those
rich in talc and in magnesite occur notably in various Nigerian localities some of
which include Wonu, Iseyin, Ilesha, Isanlu, Egbe and Tegina.
The above mentioned places show the various forms/types in which talc
mineralization occurred in Nigeria, including the geologic & petrographic
properties.
Wonu
In Wonu area, talc bodies are found as lenses and bands along a belt with a
composite Northerly strike length of about 4 km, they are closely related with
amphibolites, quartzites and quartz veins. The area is generally thickly forested
and the depth of weathering is penetrating, which could explain for the relatively
poor exposure of the rocks. Besides, talc which may be over 80%, samples
contains in addition, various proportions of tremolite, anthophyllite, chlorite,
muscoviteand serpentine. X-ray studies of some also reveal the presence of
kaolinite and goethite. Specimens obtained towards the margins of some bodies
with amphibolites, tend to be rich in tremolite observed as Irregular plates in a
matrix of acicular talc.
Ilesha
Talc bodies are widely distributed within the Ilesha amphibolite complex, and are
commonly associated with structural elements. The Ilesha Units are generally
similar to those of Wonu, and anthophyllite, tremolite/actinolite and/or Chlorite

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may be significant contents of some outcrops. Muscovite-bearing types usually are
more fissile. (Elueze and Ogunniyi, 1985) have suggested that minerals such as
kaolinite detected in some diffractograms, were perhaps formed from subsequent
alteration.
Iseyin
In Iseyin district (roughly 90 km northwest of Wonu), talcose rock occur
along possible fracture zones (Rahaman, 1973). They are also found as relatively
small void and lenticular masses, which seldom exceed 2 km in strike length. The
enclosing and related rocks include biotite-garnet/staurolite schists, quartzites and
amphibolites.
The Iseyin talc deposits comprise massive and foliated types. Talc is usually
the, oft abundant, and other components found in different percentage, are
chlorite, tremolite/actinolite and muscovite. A variety has been described to
contain subordinate amounts of quartz and pyroxene partially replaced by talc.
Opaque Minerals and sphene are accessory constituents of most samples.
Isanlu
Around Isanlu in Egbe Area, Talc-rich rocks are emplaced prominently
along a northeasterly belt extending for over 3 km. Variation in colour of
exposures also reflect compositional disparities, and those bearing tremolite and/or
chlorite tend to be greenish. On the other hand, outcrops that are largely talc are
whitish and may be massive.

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The talc bodies are again intimately associated with
amphibolites/amphibole schists and micaceous schists. In addition, quartzitic
rocks and quartz veins are encountered within the belt. Cataclastic features are
observed commonly in adjacent amphibolites, which may be evidence of shearing
along this zone.
CHAPTER FOUR
PETROGRAPHIC VARIETIES
Meta-ultramafites are present within the schist belts, in close association
with amphibolites. They are generally widespread, but individual occurrences are
usually of restricted extent of a few square kilometers. The ultramafic schists are
commonly found as lenses and bands intercalated with amphibolites and
metasedmients,often along lineament structures. Various units are localized in
South-western Nigeria, besides the occurrences in the Egbe and Ilesha- Apomu
areas, (Rahaman 1973) has shown that amphibolites and ultramafic schists are
closely associated with belts of low-medium grade politic schists in the Iseyin
district (about 150 km NW of Ilesha). In these occurrences, talc-bearing schist
constitute the pre-dominant class and outcrops may contain essential or minor
quantities of tremolite, actinolite, serpentine, anthophyllite, chlorite and/or
Magnesite. However, some units contain one or more of these other mineral as the
dominant component, with scanty amount of talc. Foliation marked by the
alignment of platy or flaky constituents is strong in most outcrops, althoughsome
may be asbestiferous or massive in character. In general, one or more
mineralogical and/or textural variety of rock may be present in a single occurrence.

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Talc schists are usually well foliated as defined by alignment of fine platy to
fibrous aggregates of talc. Those rich in tremolite may exhibit imperfect
schistosity, whereas the micaceous types are usually more fissile compared to other
varieties. Outcrops are frequently found as relatively small low-lying exposures.
Variations in megascopic properties of the samples are reflected in features
observed in thin sections. Samples of talc schist often display well marked
parallelism of fibrous aggregates and platelets of talc. In thin sections of talc-
tremolite schists, tremolite forms slender grains, fibrous aggregates and irregular
plates set in a finer-grained felty matrix of flaky talc. Tremolite may be replaced by
platy crystals of talc. Radial-fibrous or stellate groups and plaited aggregates of
talc flakes are usually present in the thin sections of talc-serpentine schists.
Tremolite rocks compared to talcoserocks, generally are pale green in colour
and often form rather extensive masses of outcrops. They commonly grade into
amphibolites and amphibolite schists. Tremolite/actinolite – anthophyllite schists
form extensive hills within the amphibolite complex, and bands of tremolite-
anthophyllite rocks occur within the amphibolite complex, and bands of tremolite-
anthophyllite rocks occur within amphibolites in Tegina and Maru areas. The
common minor constituents of these meta-ultramafites include chlorite, talc, and
sometimes serpentine. Carbonates and ore minerals are usually present as
accessory constituents.
In some, the ore minerals include chalcopyrite and pyrrhotite, which may be
found in various stages of decomposition (Elueze, 1981). The related amphibolites
and amphibole schists are mostly mostly hornblendites and hornblende schists
usually containing some plagioclase, magnetite, ilmenite and sulfides.

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Occurrences of chlorite schists and talc magnesite schists are likewise
encountered within these ultramafic complexes. Outcrops are often well oriented
parallel to the the regional northerly trend. In samples of talc-magnesite schist,
magnesite often occurs as lineated porphyroblast in a finer-grained groundmass of
plaited flakes and fibres of talc. In some thin sections, shredy aggregates of chlorite
are interstial to magnesite crystals. Whereas in chlorite schists, they are developed
to the near exclusion of other minerals, in these rocks, spinels and magnetite are
likewise present as minor or accessory constituent
CASE STUDIES
1) Baba ode talc occurrence in south western nigeria
The Baba Ode talc with a preliminary quantitative estimation of 3 million tons,
occurs in close association with a mafic complex. This complex is surrounded by a
series of compositionally variable gneisses, syenites, phillytes and mica schists,
granites and coarse pegmatites in the entire Iseyin-Oyan schist belt.
Two petrographic varieties were found, a white talcose, and a fibrous light grayish
tremolitic variety characterize the body. X- Ray and petrographic studies show that
mineralogically they comprise mainly of talc, tremolite and chlorite with
subordinate quartz and muscovite. Chemical analysis of representative samples
using Atomic Absorption Spectrometer (AAS) instrumentation methods show that
the tremolitic variety is higher in Si20 (53.97%) and Al203. (1.9%) than in the
talcose. Fe (t) as Fe203 (4.35%) and Ca0 (1.7%) content in the two varieties are
non-variable. While Mg0 values in the talcose (33.25%) is higher than in the
tremolitic type (31.39%). Concentration of Ti02, Mn02, Na0 and P205 for both
varieties does not exceed 0.25%.
Firing characteristics reveal an average loss on ignition (L.O.I) of 4.21% for the
two types. Linear shrinkage (L.S.V) average 1.35% while average water absorption
capacity is 4.1%. A flat to gently undulating topographic configuration and easy

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accessibility enhance the mineability of body. The talc bodytherefore with some
beneficiation will be useful in paper, paint, roofing and ceramic manufacturing.
2) Talc Bodies of Kagara Area, Northwestern Nigeria
The study area, Kagara and its environs, lie within the Kushaka Schist belt of the
Basement Complex of Nigeria, Tegina Sheet 142. Talcose bodies in the area occur
in relatively small sizes except in Kumanu / Indaki area where they are massive
and occuras inselbergs. The talc bodies occurin quartz ridge and pelitic-semi
pelitic rocks and make contact with amphibolites and the migmatite-gneiss.
Litho-logically, the area comprises migmatite-gneiss, quartzites, amphibolites,
peliticsemi pelitic rocks, arkosic rocks, granites and undifferentiated rock bodies.
Samples of talcose bodies and host rocks were evaluated for their physical,
mineralogical and chemical properties by petrographic, XRD and XRF analyses.
Mineralogically, the talc bodies contain varying proportions of talc, tremolite,
chlorite, anthophyllite and minor amounts of phlogopites, sapionite and stevensite
which are alteration minerals. Chemically, most of the samples have high silica
and magnesia contents >75% and CaO≤0.01%; Na2O +K2O<0.4%.
Firing tests showed some properties of talc such as colour, shrinkage, permeability
specific resistance, hardness, and strength and pore structure. It was observed that
the samples analyzed are composed ofa good percentage of talc and other minor
minerals such as clay, chlorite, anthophyllite, tremolite, sapionite and phlogopite.
Comparison of the petrographic, mineralogical, chemical and physical data with
some industrial indices indicate that the different samples have industrial potentials
for ceramics, paints, paper, textile, rubber, crayons and plastic making. With
appropriate beneficiation like floatation and bleaching, the different talc samples
can becomevaluable to the cosmetics, pharmaceuticals and food processing
industries (Ihaza C.A et al 2014)

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CHAPTER FIVE
CONCLUSION
Talc bodies are found in relatively small void and lenticular masses and also
in lenses and bands. They are often associated with enclosing minerals and related
rocks include biotite-garnet/staurolite schists, quartzites and amphibolites, quartz
veins. Talc is usually the, oft abundant up to 80%, and other components found in
different percentage, are chlorite, tremolite/actinolite, anthophyllite, muscovite.
Talc deposits are formed via hydrothermal alteration of pre-existing rocks.
In Nigeria, they occur within the Schist belt of the Basement Complex, in areas
such as Wonu, Ilesha, Iseyin and Isanlu having different geologic and petrographic
varieties.
The occurrence of talc in the country is a blessing as talc is a highly sought
mineral due to its high industrial viability.

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REFERENCES
Elueze, A. A., (1981). Geochemistry and petrotectonic setting of metasedimentary
rocks of the Schist belt of Ilesha area, S.W. Nigeria. J. Min. Geol., 18 (1):
194 – 197.
Elueze, A. A., (1982). Mineralogy and chemical nature of metaultramafites in
Nigerian schist belts.Journal of Mining and Geology, 19 (2): 21 – 29.
Elueze, A. A. and Ogunniyi, S. O., (1985). Appraisal of talc bodies of the Ilesha
district, Southwestern Nigeria, and their potentials for industrialapplications.
Natural Resources Development, 21: 26 – 34.
Geology.com http://geology.com/minerals/talc.shtml
Ihaza C.A et al (2014) Appraisal of the Talc Bodies of Kagara Area, Northwestern
Nigeria and their Industrial Potentials
Mondo Minerals www.mondominerals.com/en/talc-production/mineralogy-
geology
Obaje, N. G., (2009). Geology and Mineral Resources of Nigeria, Lecture Notes
in Earth Sciences 120, DOI 10.1007/978-3-540-92685-6 2
Olugbenga A. O et al (2013)composition features and industrial appraisal of
the baba ode talc occurrence, south western Nigeria
Rahaman, M. A., (1973). Review of the basement geology of South-Western
Nigeria. In: Kogbe CA (ed) Geology of Nigeria, 2nd edn, Elizabethan
Publishers, Lagos, pp 41–58

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Rahaman, M. A., (1981). Recent advances in the study of the basement complex
of Nigeria. Abstract, 1st Symposium on the Precambrian Geology of
Nigeria.
Turner, D. C., (1983). Upper Proterozoic schist belts in the Nigerian sector of the
Pan-African Province of West Africa. Precambrian Res 21: 55–79.
Woakes, M., Rahaman, M. A., Ajibade, A. C., (1987) Some metallogenetic
features of the Nigerian basement. J Afr Earth Sci 6:54–64.