MINERALOGY OF MINERALIZED PEGMATITE OF RAS MOHAMED … · 2020-05-08 · 2017 Vol. 7 (1) January-April, pp. 65-80/Raslan et al. Research Article Centre for Info Bio Technology (CIBTech)

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2017 Vol. 7 (1) January-April, pp. 65-80/Raslan et al.

Research Article

Centre for Info Bio Technology (CIBTech) 65

MINERALOGY OF MINERALIZED PEGMATITE OF RAS MOHAMED

GRANITE, SOUTHERN SINAI, EGYPT

Mohamed F. Raslan, ٭Mona M. Fawzy and Hanaa A. Abu-Khoziem Nuclear Materials Authority, Cairo, Egypt

Author for Correspondence٭

ABSTRACT

An economically important rare-metal mineralization is recorded in the mineralized pegmatite injected in

alkali-feldspar microgranite of Gabal Samma at North Ras Mohammed granitic pluton, Southern Sinai,

Egypt. The studied mineralization was found as distinguishable megascopic crystals scattered within the

pegmatitic bodies of Gabal Samma granite and reach up to tens of centimeters. The mineralogy and

geochemistry of the studied rare metal mineralization were determined using microscopic examination

and X-ray Diffraction (XRD) as well as scanning electron microscope (SEM). These minerals include a

unique occurrence of colored ishikawaite (uranium- rich samarskite) together with fergusonite-Y, allanite,

titanite, zircon-thorite association, uranothorite and fluorite. The obtained SEM data for the studied

minerals are showing the compositional limits of these minerals as specified in the literature. The

occurrence of colored ishikawaite varieties (light brown, reddish dark brown and dark greenish brown)

was recorded for first time in Egypt. The analytical data indicate that the increased color intensity of

ishikawaite mineral is most probably due to increase of uranium content. Accordingly, Nb, Ta, Y, U, and

REE together with Zr and Th mineralization of the Ras Mohamed pegmatite can be considered as a

promising target ore for its rare-metals.

Keywords: Mineralized Pegmatite, Ishikawaite, Fergusonite-Y, Allanite, Titanite, Zircon-Thorite

Association, Uranothorite, Southern Sinai

INTRODUCTION

Several rare metal mineralization occurrences have been recorded in different localities of the Eastern

Desert and South Sinai of Egypt.

However, these mineralizations are mainly restricted to the granite pegmatite bodies associated with the

younger granite that are widely distributed in the Eastern Desert (Ibrahim et al., 1996; Abdalla et al.,

1998; Ibrahim, 1999; Ammar, 2001; Abdalla and El Afandy, 2003; Ali et al ., 2005; Abd El Wahed et al.,

2005; Raslan, 2005; Abdel Warith et al., 2007; Raslan et al., 2010 a & b; Raslan and Ali, 2011; Raslan,

2015) and South Sinai (El Aassy et al., 1986; El Reedy et al., 1988; Abdel Monem et al., 1997; Saleh,

2006; Bisher, 2007; Abu Khoziem, 2012).

Several studies worldwide have revealed the presence of granite-pegmatite-hosted rare-metal

mineralizations including Nb-Ta oxides and zircon (e.g., Matsubara et al., 1995; Erict, 2005; William et

al., 2006 and Pal et al., 2007). Rare-metal mineralization can be attributed either to magmatic or post-

magmatic metasomatic processes (Schwartz, 1992; Abdalla et al., 1998).

The study area is located in the Southern most part of Sinai Peninsula at North Ras Mohamed area

between latitudes 27° 47` – 28° 9`N and longitudes 33° 55` – 34° 24`E (Figure 1). The area is traversed

by regional road between El-Tour City on the Gulf of Suez and Sharm El-Sheikh City and several desert

roads.

Topographically, the study area is distinguished from the Northern part by its rugged terrain and relief,

and characterized by low, moderate to high topographic features. It includes Gabal (G) Khashabi, G.

Attsharqi, G. Sahara, G. Samma, G. Umm-Adawi and G. Mezriya. The general elevation decreases gently

from the east to the west. The main Wadis (streams) dissecting the area are Wadi (W) Lathi, W. Umm-

Adawi, W. Mander, W. Ngeibat, W. Khashabi, W. Sahiya and W. Att El Gharbi. Some of these wadis

drain ultimately into the Gulf of Aqaba and others into the Gulf of Suez.




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The aim of the present paper is to identify mineralogical and chemical characteristics of radioactive as

well as economic heavy minerals of pegmatites associating alkali-feldspar microgranite of the G. Samma

from N.W. Mander.

Geologic Setting

Based on the field observations and relationships, the rock units can be arranged chronologically,

beginning with the youngest, as following (Figure 2): sedimentary cover, post Cambrian dykes, post

Cambrian granites, Cambro-Ordovician Araba Formation, post-granitic dykes (precambrian dykes),

pegmatites and aplites, Younger granites (alkali-feldspar microgranite, alkali-feldspar granite,

syenogranite, monzogranite), dokhan volcanic, older granites and metamorphic rocks (the oldest), Abu

Khoziem (2012).

Pegmatites are considered as the most abundant rocks bearing anomalous radioactive signature. The

pegmatites and aplites are disseminated among all granitic types. The pegmatites occur as simple or

complex aggregate pockets and dykes. According to radioactivity magnitude, more interesting pegmatites

are the following: 1-Alkali-feldspar microgranite of G. Samma occurs as pod-like bodies with an oval

shape extending for about 100 m. 2-Monzogranite of W. Um Adawi occurring as pockets varying in size

from 0.5 to 30 m and dykes with thickness of about 25 cm and extent of about 15 m. 3- The contact

between the monzogranite and the alkali-feldspar granite at the upstream side of W. Lathi. Pegmatites

occur as dykes with thickness of about 50 cm and extent of about 20 m. 4-Monzogranite at the

downstream side of W. Umm Malaq, where pegmatites occur as dykes with thickness of about 50 cm and

extent of only about 75 cm. 5-Akali-feldspare granite in the Eastern side of G. Att El Sharqi, where

pegmatites occur as small pockets varying in size from 0.25 to 0.75 m.

The Nb-Ta mineralization associated with pegmatites can be distinguished even by naked eye especially

in W. Lathi, W. Um Adawi and N.W. Mander (Figure 3). On the other hand, non-radioactive pegmatites

are widely distributed in the studied area within all granitic types. They are recorded both as zoned and

unzoned pockets that vary in size from 0.5 to 50 m.

Figure 1: Location Map of the Study Area




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Figure 2: Geological Map of the Studied Area North Ras Mohamed, South Sinai, Egypt (After

Saleh, 2006)

Figure 3: Close-up Photographs Showing A- Rare Metal Mineralization Associated to Pegmatite

Present as Large Black and Brown Grains; B- Vugs Filled with Nb-Ta Oxide Minerals




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Sampling and Analytical Techniques A large bulk composite sample representing different mineralized zones of pegmatite bodies associating

the alkali-feldspar microgranite of G. Samma from N.W. Mander and weighing approximately 70 kg was

collected for mineralogical investigation. The sample was crushed, ground, and sieved before subjecting

the liberated size fractions to heavy-mineral separation, using bromoform (specific gravity = 2.85 g/cm3).

The heavy mineral grains were manually picked from each of the obtained heavy fractions under

binocular microscope. Some of these selectively picked grains were analyzed by X-ray diffraction

technique (XRD) after heat treatment using Philips X-ray generator model PW 3710/31 a diffractometer

with automatic sample changer model PW1775 (21 position). The X-ray radiation used is Cu-target tube

and Ni filter at 40 kV and 30 mA. This instrument is connected to a computer system using X-40

diffraction program and ASTM cards for mineral identification. The metamict state is characterized by

structure disorder (amorphous to X-rays) while the crystal habit is frequently well developed. The

essential features of this state were discussed by Pabst (1952). The metamictic state can be changed by

appropriate heating of such mineral at temperatures higher than 400 °C leading to their recrystallization.

Some of the separated grains were examined by Scanning Electron Microscope (SEM). This instrument

includes a Philips XL 30 energy-dispersive spectrometer (EDS) unit. The applied analytical conditions

were an accelerating voltage of 30 kV with a beam diameter of 1μm for a counting time of 60-120 s and a

minimum detectable weight concentration ranging from 0.1 wt % to 1wt %. All these analyses were

carried out at the laboratories of the Egyptian Nuclear Materials Authority (NMA).

RESULTS AND DISCUSSION The systematic and detailed mineralogical examination of the heavy minerals obtained from the bulk

composite sample of Ras Mohamed pegmatite revealed the presence of several economic minerals. Thus,

in addition to the Nb-Ta oxide minerals (ishikawaite and fergusonite), a Th-U mineral (thorite or

uranothorite) was discovered in close association with zircon. Microscopic examination of the heavy

fractions of the four size classes (− 0.800+ 0.600 mm), (− 0.600 + 0.400 mm), (− 0.400 + 0.200 mm), and

(− 0.200 + 0.063 mm) revealed that the content of the accessory minerals in the bulk composite sample of

the studied Ras Mohamed pegmatite amounts to approximately 2.5 wt %. The contents of heavy and

accessory minerals have been determined using the counting technique. These data indicate that

ishikawaite (uranium-rich samarskite) is the predominant mineral followed by zircon-thorite association

and allanite in all size fractions (− 0.800-0.063 mm). In addition to those minerals, fergusonite, titanite,

and fluorite occur in much lower amounts.

Niobium-Tantalum Oxide Minerals

A. Ishikawaite (Uranium-Rich Samarskite): (Fe, U, Y) (Nb, Ta) O4

Under the binocular microscope, the examined ishikawaite crystals were found to be distributed in almost

all size fractions between 0.800 mm and 0.063 mm. The defined ishikawaite (uranium-rich samarskite)

crystals are generally massive grains of anhedral to subhedral and granular form and having a

characteristic vitreous or resinous luster.

Also, the investigated mineral crystals are generally translucent, compact, metamict and hard. It is

interesting in this regard to mention that ishikawaite in the studied samples exhibits a wide range of

colors.

Some of the grains are yellowish brown, while others are reddish dark brown and dark greenish brown

with different gradations. It is worth to mention that nearly all ishikawaite grains cited in the previous

literature in Egypt are black in color (Raslan, 2008). Therefore, the presence of colored varieties of

ishikawaite in the studied samples was recorded for the first time in Egypt. Scanning Electron Microscope

(SEM) data of the studied ishikawaite grains show that the mineral is enriched in niobium, uranium and

thorium. The obtained data of the investigated ishikawaite of yellowish brown color (Figure 4A and B),

dark reddish brown ishikawaite (Figures 4C and D) and dark greenish brown color (Figsure 4E & F) are

shown in Table 1.




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Table 1: SEM Chemical Analyses of Different Colors of Ishikawaite

Dark Greenish Brown Reddish Dark Brown Yellowish Brown Element Oxide

35.7 48.7 58.1 Nb2O5

1.0 2.6 2.6 Ta2O5

1.1 1.3 2.1 TiO2

29.6 19.3 9.9 UO2

5.2 4.7 9.8 ThO2

3.5 4.1 2.7 FeO

8.7 5.0 - Y2O5

3.3 4.2 3.9 CaO

- - 5.6 PbO2

- - 0.5 Ce2O3

- - 0.6 Nd2O3

2.0 2.1 - Al2O3

0.6 0.6 - MnO

8.4 5.7 4.2 SiO2

1.0 1.7 - Sc2O3

100 100 100 Total

Samarskite is a group of the Nb-Ta mineral varieties occurring in pegmatite granites and having the

general formula Am Bn O2 (m+n) where A represents Fe2+

, Ca, REE, Y, U and Th while B represents Nb,

Ta and Ti. According to Hanson et al., (1999), the complete metamict state, alteration and the broad

variation of cations in A-site of these mineral varieties render their crystal structure a problematic case.

Therefore, these authors have proposed a nomenclature for the samarskite group of minerals based on

their classification into three species.

Thus, if the REE + Y are the dominant, the name samarskite-(REE + Y) should be used with the dominant

of these cations as a suffix. If U + Th are the dominant, the mineral is properly named ishikawaite

whereas if Ca is the dominant cation, the mineral should be named calciosamarskite. Hanson et al., (1999)

have also reported that ishikawaite and calciosamarskite are depleted in the light rare-earth elements

(LREE) and enriched in the heavy rare-earth elements (HREE) together with Y. Recently, samarskite-

(Yb) has been identified as a new species of the samarskite group (William et al., 2006). It is interesting

to mention that ishikawaite with an average assay of about 50 % Nb2O5 and 26 % UO2 has been identified

for the first time in Egypt in the mineralized Abu Rushied gneissose granite (Raslan, 2008). From the

obtained data, it is quite clear that the studied Nb-Ta mineral variety of Ras Mohamed pegmatite reflects

the chemical composition of U and Th-rich samarskite species. The lines of evidence of the latter

(ishikawaite) can be summarized as follows:

1. The obtained SEM data revealed that Nb2O5 is dominant in the investigated mineral where it attains

content of 58.14 wt % in the yellowish brown variety. The sum of average content of Ta2O5 and TiO2

attains 4.76 wt %, which is much lower than content of Nb2O5. Also, Nb2O5 is dominant in the reddish

dark brown variety (48.68 wt %) and the sum of average content of Ta2O5 and TiO2 attains 3.90 wt %,

which is much lower than content of Nb2O5. The Nb2O5also is dominant in the dark greenish brown

variety (35.72 wt %) and the sum of average content of Ta2O5 and TiO2 attains 2.13 wt %, which is much

lower than content of Nb2O5. The samarskite group comprises only those species in which the Nb content

in B-site is higher than that of Ta and Ti (Hanson et al., 1999).

2. The studied mineral actually falls within the compositional limits of both samarskite-Y and ishikawaite.

Both samarskite-Y and ishikawaite have a dominant Nb in the B-site and the distinction between the two

varieties must be based on the content of A-site occupancy.

3. Samarskite-Y has been described as a mineral with Y + REE dominant at the A-site (Nickel and

Mandarino, 1987).




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4. The investigated mineral is actually rich in both uranium and thorium, where the yellowish brown

variety contain (9.88 %) and (9.80 %) respectively. The dark brown variety contains U (19.29 %) and Th

(4.73), whereas the dark oily or dark greenish brown variety contains 29.57 % and 5.21 % for uranium

and thorium respectively.

5. The investigated samarskite variety separated from the Ras Mohamed pegmatite is characterized by

dominant U + Th, Nb> Ta + Ti and relatively rich in Y.

6. In summary, the studied mineral most probably falls within the compositional limits of other

ishikawaite cited in the previous literature.

Finally, the analytical data indicate that increasing color intensity of ishikawaite mineral is most probably

due to increasing of uranium content; the uranium content increase gradually from 9.88 % in the lighter

colored variety to 19.29 % in the reddish darker brown, and to 29.57 % in the very deep colored variety.

B. Fergusonite-Y: (Y, REE>Ca, U, Th) (Nb, Ta) O4

Under the binocular microscope, the defined fergusonite grains are generally massive grains of anhedral

to subhedral and granular form and having a characteristic vitreous or resinous luster. Also, the

investigated mineral crystals are generally translucent, compact, metamict and hard. The fergusonite

crystals are mainly velvet-yellow brown to honey yellow in color.

The SEM data of the studied fergusonite crystals (Figures 4G and H) show that the mineral is enriched in

niobium, yttrium and REE elements. The obtained SEM analyses of the investigated fergusonite of

velvet-yellow brown to honey yellow color (Figures 4G and H) have resulted in Table 2.

Table 2: SEM Chemical Analyses of Fergusonite-Y

Wt. (%) Element Oxide

41.0 Nb2O5

3.6 Ta2O5

14.1 Y2O5

27.3 ΣREE

3.2 UO2

5.5 ThO2

0.7 CaO

3.4 Al2O3

1.0 MgO

100 Total

The fergusonite group consists of REE-bearing Nb and Ta oxides, many of which are metamict and

therefore, commonly poorly characterized. The structure of fergusonite group is comparable to that of

samarskite group but with large A-sites. Most of these minerals are monoclinic, although orthorhombic

and tetragonal unit cells arise from cation ordering. Similar to other (Y, REE, U, Th)-(Nb, Ta, Ti) oxides,

fergusonite (ideal formula: YNbO4), occurs typically as an accessory component in granites (Poitrasson et

al., 1998) and granitic pegmatites (Ercit, 2005). Accordingly, the obtained data reflect the chemical

composition of fergusonite-Y and show that the mineral is enriched in niobium (41.03 wt %) in B-site,

yttrium (14.14 wt %) and total REE elements (27.33 wt %) in A-site.

Pure monomineralic sample from ishikawaite grains of various colors and fergusonite were prepared by

hand picking and subjected to XRD analyses. The obtained XRD data for ishikawaite and fergusonite

after annealing (heat treatment) are presented in (Figure 5A & B). The data conforms to the ASTM cards

index No. 10-398 and 4-0617 for samarskite and No. 9-443 for fergusonite-Y.




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Figure 4: A- Ishikawaite Crystals with Yellowish Brown Color; B- EDX and BSE Image of

Yellowish Brown Ishikawaite; C- Ishikawaite Crystals of Reddish Dark Brown Color; D- EDX and

BSE Image of Reddish Dark Brown Ishikawaite; E- Ishikawaite Crystals with Dark Greenish

Brown Color; F- EDX and BSE Image of Dark Greenish Brown Ishikawaite; G- Fergusonite

Crystals with Velvet-Yellow Brown to Honey Yellow in Color; H- EDX and BSE Image of

Fergusonite Crystals




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Figure 5: A-XRD Diffractograme of Various Colors Ishikawaite; B- XRD Diffractograme of

Fergusonite-Y

Zircon-Thorite Association

Under a binocular microscope, zircon occurs as dark brown massive compact grains that are generally

translucent to opaque (Figure 6A). The surface of the zircon grains is generally ill-defined, rough, and

dull. It possesses a zonal structure with almost translucent to isotropic zones. Morphologically, some

crystals are typically short to equidimensional, with a length/width ratio of 1:1, and they tend to exhibit

square to trapezoid, rhombic or hexagonal cross sections (Figures 6 B & C). Other zircon grains occur as

bright yellow massive compact crystals (Figure 6D). Scanning electron microphotographs confirm that

A

B




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almost all the investigated zircon crystals characteristically contain several black inclusions of thorite

(Figures 6 B, C & E).

In addition, several zircon crystals were subjected to semi quantitative analyses using SEM. While the

SEM microphotograph (Figures 6B & C) reflect morphological features of the investigated zircon as well

as its uranothorite inclusions, the SEM analysis (Figures 6B & C) and Table 3 confirm the semi

quantitative chemical composition of zircon and the thorite inclusion, respectively.

However, the latter tends to be uranothorite species due to the presence of a remarkable amount of

uranium (11.43 %) together with Th (35.81 %) and Si (13.27 %). The uranothorite inclusions are present

in variable sizes ranging from 1 μm to 40 μm. They occur either as numerous minute inclusions in a zonal

distribution pattern, especially in the outer zone of the zircon grain (Figures 6B & 6C), or as randomly

distributed inclusions of varying sizes (Figures 6E).

Zircon incorporates uranium into its lattice and encloses the radioactive materials as minor inclusions.

The observed color changes of zircon have long been a matter of debate.

The documented high contents of U, Th and REE may enhance metamictization and color variation of

zircon. It is noteworthy that Ali et al., (2005); Abdel Warith et al., (2007); Raslan, (2009); Raslan et al.,

(2010b) reported the presence of thorite inclusions in rare-metal mineralization and accessory heavy

minerals (zircon, samarskite and spessartine garnet) that are separated from some Egyptian granitic rocks

and their associated pegmatites.

Table 3: SEM Chemical Analyses of Dark Brown and Yellowish Brown Zircon

Yellowish Brown Zircon Dark Brown Zircon Elements

57.5 68.3 Zr

14.7 2.0 Th

4.7 1.6 U

3.2 2.9 Hf

7.3 2.2 Fe

11.6 19.5 Si

1.1 2.1 Ca

- 1.6 Al

100 100 Total

Uranothorite: [ (Th,U) SiO4]

Uranothorite occurs as pale to dark yellow brown grains that are generally translucent to opaque. They are

found as massive grains of anhedral to subhedral and granular form, having a characteristic vitreous or

resinous luster (Figure 6F). Scanning Electron Microscope (SEM) data (Figure 6 G & H) and Table 4

reflects the morphological features and chemical composition of uranothorite. These results indicate that

the major elements in uranothorite are ThO2 (59.61 wt %), SiO2 (15.47 wt %) and UO2 (14.28 wt %).

Also, minor amounts of Fe2O3 (1.42 wt %) and CaO (1.48 wt %) were reported as substitution in

uranothorite.

Table 4: SEM Chemical Analyses of Uranothorite


15.5 SiO2

1.5 CaO

1.4 Fe2O3

59.6 ThO2

14.3 UO2

7.8 ZrO2

100 Total




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Figure 6: A- Zircon Crystals with Dark Brown Color; B- EDX and BSE Image of Zircon; C- EDX

and BSE Image Showing a Zonal Structure in Zircon and Uranothorite Inclusions; D- Zircon

Crystals with Light Brown Color; E- EDX and BSE Image of Zircon and Uranothorite Inclusions

together; F- Uranothorite Grains with Dark Brown Color; G- BSE Image of Uranothorite; H-

EDX of Uranothorite




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REE-Bearing Minerals

A. Allanite: [(Ca, REE, Th)2 (Fe2+

,Al)3 Si3O12 (OH)]

Allanite occurs as black massive translucent crystals of anhedral to subhedral form and has a

characteristic vitreous luster (Figure 7A). SEM data of the studied allanite crystals (Figure. 7B) show that

the mineral is enriched in silica, alumina, iron, calcium and REE elements. The obtained SEM analyses of

the investigated allanite have resulted in Table 5.

The accessory mineral allanite [(Ca, REE, Th)2 (Fe2+

,Al)3 Si3O12 (OH)] is a prime target for dating

geological processes because it plays a key role in the storage and mobility of geochemically important

trace elements including the rare earth elements (REE), strontium and thorium. Allanite occurs in a wide

range of rock types, but is most commonly reported as an accessory phase in metaluminous granites to

tonalites and pegmatites (Exley, 1980; Giere and Sorensen, 2004).

Table 5: SEM Chemical Analyses of Allanite

Wt. (%) Elements Oxide

33.3 SiO2

13.4 Al2O3

17.2 Fe2O3

9.5 CaO

11.1 Ce2O3

10.6 La2O3

0.9 Nd2O3

0.6 Pr2O3

2.0 MnO

1.4 ThO2

100 Total

B. Titanite: [CaTiSiO5]

Titanite occurs as brownish yellow massive translucent crystals of anhedral to subhedral form and having

a characteristic vitreous luster.

Generally, it is widespread as an accessory mineral occurring in igneous rocks. It is a calcium titanium

silicate mineral (CaTiSiO5) with sphenoid habit.

The brown color of titanite is attributed to presence of Fe2O3, whereas the yellow varieties are low in iron

content and brown or black titanite may carry 1%, or more, Fe2O3 (Deer et al., 1962). Some titanite

crystals have been found to be metamicted. The obtained SEM analyses of the investigated titanite

(Figure 7C) have resulted in Table 6.

Scanning electron microphotographs confirms that almost all the investigated titanite crystals

characteristically contain several bright inclusions enriched in Y2O3 (22.04 wt %) and P2O5 (7.85 wt %)

most probably due to xenotime substitution (Figure 7D).

Table 6: SEM Chemical Analyses of Titanite


15.0 Al2O3

36.7 SiO2

22.7 CaO

17.1 TiO2

0.8 Nd2O3

0.8 MnO

7.0 Fe2O3

100 Total




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Figure 7: A- Allanite Crystals; B- EDX and BSE Image of Allanite; C- EDX and BSE Image of

Titanite; D- EDX of Bright Inclusions in Titanite; E- Colorless, Rose and Pink Fluorite Crystals; F-

BSE Image and EDX Spectrum of Fluorite

C. Fluorite: CaF2

The fluorite occurs as colorless and colored transparent crystals. They are present as cubes and are

characterized by a vitreous luster. The majority of the fluorite crystals occur as multicolored or as rose,




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pink and blue to violet (Figure 7E). The obtained SEM analyses confirm the chemical composition of

fluorite (Table 7).

Table 7: SEM Chemical Analyses of Fluorite


30.7 F2O

1.4 Y2O3

67.9 CaO

El-Kammar et al., (1997) remarked that the change in the color in the fluorite is controlled by the Y

content, in particular, and the Y group, in general. Several workers attributed the color of the fluorite to

the effect of radioactivity (Deer et al., 1962; Mackenz and Green, 1971; Nassau and Prescott, 1977;

Raslan, 2000). The results of SEM analysis were confirmed by XRD analysis. Mono-mineralic sample

from allanite and titanite crystals were prepared by hand picking and analyzed using XRD technique. The

obtained data are presented in Figure 8. The diffraction lines are in accordance with the ASTM cards No.

(9-474) for allanite and No. (11-142) for titanite.

Figure 8: A- XRD Diffractograme of Allanite; B- XRD Diffractograme of Titanite

Conclusion

Microscopic investigation, SEM, and XRD analyses confirm the presence of ishikawaite mineral species

in the mineralized pegmatite injected in alkali-feldspar microgranite of Gabal Samma at North Ras

Mohammed granitic pluton, Southern Sinai, Egypt. The mineral is associated with fergusonite-Y, allanite,

titanite, zircon-thorite association, uranothorite and fluorite. The occurrence of colored ishikawaite

varieties (light brown, dark reddish brown and dark greenish brown) was recorded for the first time in

Egypt. The analytical data indicate that the increasing of color intensity of ishikawaite mineral is most

probably due to increasing uranium content. The studied pegmatite has high economic potentiality as a

source far as nuclear materials is concerned.

REFERENCES Abd El Wahed AA, Abd El Mottalib AA and Sadek AA (2006). Mineralogical and radio-metrical

characteristics of rare- metal pegmatite at southern Humr Waggat Pluton, Central Eastern Desert, Egypt.

Journal of Middle East Research Center. Ain Shams University, Cairo 19 105-116.




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Abd El Wahed AA, Raslan MF and El Husseiny MO (2005). Radioactive pegmatites of Um Lassifa

granitic pluton, Central Eastern Desert, Egypt: Mineralogical investigation, The 9th International Mining,

Petroleum and Metallurgical Engineering Conference, Faculty of Engineering-Cairo University 12.

Abdalla HM and El Afandy AH (2003). Contrasting mineralogical and geochemical characteristics of

two A-type pegmatite fields, Eastern Desert, Egypt. Egyptian Mineralogists 20 287-328.

Abdalla HM, Helba HA and Mohamed FH (1998). Chemistry of columbite-tantalite minerals in rare

metal granitoids, Eastern Desert, Egypt. Mineralogical Magazine 62 821-836.

Abdel Monem AA, El Aassy IE, Hegab OA, El-Fayoumy IF and El-Agami NL (1997). Gibbsite,

uranium and copper mineralization, Um Bogma area, Southwestern Sinai, Egypt. Journal of

Sedimentology, Egypt 5 117-132.

Abdel Warith A, Raslan MF and Ali MA (2007). Mineralogy and radioactivity of pegmatite bodies

from the granitic pluton of Gabal Um Tager El-Tahtani area, Central Eastern Desert, Egypt. The 10th

International Mining, Petroleum, and Metallurgical Engineering Conference, March 6-8 2007, Mining,

Code No. M3, Faculty of Engineering- Cairo University.

Abu Khoziem HA (2012). Characterization and leaching potentialities of some rare metals from

mineralized rocks, Southern Sinai, Egypt, unpublished Ph.D. Thesis, Faculty of Science, Cairo

University, 223.

Ali MA, Raslan MF and El-Feky MG (2005). Radioactivity and mineralogy of some pegmatite bodies

from Gabal Al-Farayid granites, South Eastern Desert, Egypt. The 9th International Mining, Petroleum,

and Metallurgical Engineering Conference, Faculty of Engineering- Cairo University.

Ammar FA (2001). Mineralogical and radiometric studies on the uraniferous pegmatites of Abu-Dob

area. Journal of Environmental Research 4 52-84.

Berman R (1957). Some physical properties of naturally irradiated fluorite. American Mineralogist 42(3-

4) 191.

Bishr AH (2007). Factors controlling mineralization of some shear zones in granites, South Sinai, Egypt.

Unpublished Ph. D. Zagazig University, Faculty of Science.

Cerny P (1990). Distribution, affiliation and derivation of rare-element granite pegmatites in Canadian

Shield. Geologische Rundschau 79 183-226.

Deer WA, Howie RA and Zussman J (1962). Rock Forming Minerals, Non Silicates, (John Wiley and

Sons, New York, USA) 5 1-371.

Deer WA, Howie RA and Zussman J (1986). Rock Forming Minerals, 2nd edition, 1A, (Longmans,

London, UK)

Deer WA, Howie RA and Zussman J (1992). An Introduction to the Rock Forming Minerals, second

edition, (Longman Group Limited, London, England).

Dollase WA (1971). Refinement of the crystal structures of epidote, allanite and hancockite. American

Mineralogist 56 447-64.

El Aassy I, Botros NH, Abdel Razik A, El Shamy AS, Ibrahim SK, Sherif HY, Attia KE and Moufei

AA (1986). Report on proving of some radioactive occurrences in west central Sinai. International Report

of Nuclear Materials Authority, Cairo, Egypt.

El Reedy MW, Mahdy MA, El Aassy IE and Dabbour GM (1988). Geochemical studies of some

uraniferous sedimentary rock varieties of West Central Sinai, Egypt. In: Fourth Conference on Nuclear

Sciences and Applications, Cairo, Egypt, I, 224-229.

EL-Kammar AM, EL-Hazik NT, Mahdi M and Ali N (1997). Geochemistry of accessory minerals

associated with radioactive mineralization in the Central Eastern Desert, Egypt. Journal of African Earth

Sciences 25(2) 237-252.

Ercit TS (2005). Identification and alteration trends of granitic-pegmatite-hosted (Y, REE, U, Th)–(Nb,

Ta, Ti) oxide minerals: a statistical approach. Canadian Mineralogist, 43(4) 1291–1303.

Ervanne H (2004). Uranium oxidation states in allanite, fergusonite and monazite of pegmatites from

Finland. Neues Jahrbuchfür Mineralogie, Monatshefte 7 289-301.




Research Article


Ewing RC (1975). Alteration of metamict, rare-earth, AB2O6- type Nb–Ta–Ti oxides. Geochimica et

Cosmochimica Acta 39 521–530.

Exley RA (1980). Microprobe studies of REE-rich accessory minerals: implications for Skye granite

petrogenesis and REE mobility in hydrothermal systems. Earth and Planetary Science Letters 48 97-110.

Gieré R and Sorensen SS (2004). Allanite and other REE-rich epidote-group minerals. Reviews in

Mineralogy and Geochemistry, 56, 431-493.

Hanson SL, Simons WB, Falster AU, Foord EE and Lichte FE (1999). Proposed nomenclature for

samarskite-group minerals: new data on ishikawaite and calciosamarskite. Mineralogical Magazine 63

27–63.

Ibrahim ME (1999). Occurrence of U and REE-bearing samarskite in the Abu Dob pegmatites, Central

Eastern Desert, Egypt. Proceeding of Egyptian Academic Science 49 77-89.

Ibrahim ME, Shalaby MH and Ammar SE (1996). Preliminary studies on some uranium and thorium

bearing pegmatites at G. Abu Dob, Central Eastern Desert. Proceeding of Egyptian Academic Science 47

173-188.

Kimura K (1922). Ishikawaite: A new mineral from Ishikawa, Iwaki. Journal of the Geological Society

of Tokyo (in Japanese) 29 316–320.

Mackenzie KJD and Green JM (1971). The cause of coloration in Derbyshire Blue John banded fluorite

and other blue banded fluorites. Mineralogical Magazine l. 38(296) 459-470.

Matsubara S, Kato A and Matsuyama F (1995). Nb-Ta minerals in a lithium pegmatite from

Myokenzen, Ibaraki Prefecture, Japan. Mineralogical Journal 17 338–345.

Nassau K and Prescott BE (1977). Smoky, greenish yellow and other irradiation - related color in

quartz. Mineralogical Magazine 41(319) 301- 312.

Nicke lEH and Mandarino JA (1987). Procedures involving the IMA Commission on New Minerals

and Mineral names, and guidelines on mineral nomenclature. Canadian Mineralologist 25 353–377.

Omar SAM (1995). Geology and geochemical features of the radioactive occurrences of Om-Anab

granitic masses, Eastern Desert, Egypt. M. Sc. thesis, Cairo University.

Pabst A (1952). The metamict state. American Mineralogist 37 137-157.

Pal DC, Mishra B and Bernhardt HJ (2007). Mineralogy and geochemistry of pegmatite-hosted Sn-,

Ta- Nb-, and Zr- Hf bearing minerals from the south Eastern part of the Bastar- Malkangiri pegmatite

belt, Central India. Ore Geology Reviews 30 30-55.

Poitrasson F, Paquette J L, Montel JM, Pin C and Duthou JL (1998). Importance of late magmatic

and hydrothermal fluids on the Sm-Nd isotope mineral systematics of hypersolvus granites. Chemical

Geology 146 187-203.

Raslan MF (1996). Mineralogical and beneficiation studies for some radioactive granites along Wadi

Balih, North Eastern Desert, Egypt M. Sc. Thesis, Faculty of Science, Cairo University 1-183.

Raslan MF (2000). Mineralogical and physical separation studies on some radioactive granites from the

Eastern Desert, Egypt. Ph.D. Thesis, Faculty of Science, Cairo University 204.

Raslan MF (2005). Mineralogy and physical upgrading of Abu Rusheid radioactive gneiss, South Eastern

Desert, Egypt. The 9th International Mining, Petroleum and Metallurgical Engineering Conference,

Faculty of Engineering-Cairo University 27.

Raslan MF (2008). Occurrence of Ishikawaite (Uranium-rich Samarskite) in the Mineralized Abu

Rushied Gneiss, South Eastern Desert, Egypt. International Geology Review Journal, 50 1132–1140.

Raslan MF (2009a). Mineralogical and geochemical characteristics of uranium-rich fluorite in El-

Missikat mineralized granite, Central Eastern Desert, Egypt. Geologija 52(2) 213-220.

Raslan MF (2009b). Mineralogical and Minerallurgical characteristics of samarskite-Y, columbite and

zircon from stream sediments of the Ras Baroud area, Central Eastern Desert, Egypt. The Scientific

Papers of the Institute of Mining of the Wroclaw University of Technology, Wroclaw, Poland, No.126,

Mining and Geology XII 179-195.




Research Article


Raslan MF (2015). Occurrence of Samarskite-Y in the Mineralized Umm Lassifa Pegmatite, Central

Eastern Desert, Egypt. Geologija 58(2) 213–220.

Raslan MF and Ali MA (2011). Mineralogy and mineral chemistry of rare-metal pegmatites at Abu

Rusheid granitic gneisses, South Eastern Desert, Egypt. Geologija, 54(2) 205–222.

Raslan MF, Ali MA and El feky MG (2010a). Mineralogy and radioactivity of pegmatites from South

Wadi Khuda area, Eastern Desert, Egypt. Chinese Journal of Geochemistry 29 343-354.

Raslan MF, El-Shall HE, Omar SA and Daher AM (2010b). Mineralogy of polymetallic mineralized

pegmatite of Ras Baroud granite, Central Eastern Desert, Egypt. Journal of Mineralogical and

Petrological Sciences 105(3) 123–134, doi: 10.2465/jmps.090201.

Saleh MM (2006). Geological and radioactive studies on the granitoids rocks, North Ras Mohamed area,

South Sinai, Egypt. Unpublished Ph.D., Faculty of Science, Suez University.

Schwartz MO (1992). Geochemical criteria for distinguishing magmatic and metasomatic albite-

enrichment in granitoids: Examples from the Ta-Li granite Yichun (China) and the Sn-W deposits Tikus

(Indonesia). Mineralium Deposita 27 101-108.

William SB, Hanson SL and Falster AU (2006). Samarskite-Yb: a new species of the samarskite group

from the Little Pasty pegmatites, Jefferson County, Colorado. Canadian Mineralologist 44(5) 1119–1125,

doi: 10.2113/gscanmin.44.5.1119.

Wing BA, Ferry JM and Harrison TM (2003). Prograde destruction and formation of monazite and

allanite during contact and regional metamorphism of pelites: petrology and geochronology.

Contributions to Mineralogy and Petrology 145 228-250.

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