Characterization of the feldspar placer deposits of Umm Shaddad Area, Eastern Desert, Egypt.

In the present study, placer feldspar resources in the Umm Shaddad region, Qusier, Egypt were invested to the appropriateness as raw materials for the glass and ceramic industries. Umm Shaddad area located west of Umm Gheig Lead Zinc Mine, at latitude 25 o 37' and 25 o 41' and longitude 34 o 19' and 34 o 24'. Chemical analyses revealed that the SiO 2 content in the analyzed feldspar placer deposit, is an average of 74.16%. This value is higher than that required for glass industries but lower than the commercial average of ceramic industries. When compared to the commercial average for glass and ceramic sectors, the average content of Fe 2 O 3 (2.48%) is considered high. The average K 2 O content in the analyzed samples is 4.77%, which is higher than the commercial values. Na 2 O content averages 3.05% and Al 2 O 3 averages 11.79%, which are lower than the commercial average for the glass and ceramic sectors. The radiometric effect of the raw feldspar of Umm Shaddad was also evaluated. Activity index of Gamma (I γ ) and Alpha (I α ), Radium equivalent activity (Ra eq ) and Hazard indices (H ex and H in ) are lower than the acceptable world value. However, the total Annual effective dose equivalent (AEDE) of the studied samples ranged between 0.82 to 1.261 with an average 1.137 which is higher than that of the world’s acceptable values. In conclusion, although the feldspar placers of Umm Shaddad have suitable content of oxides after minor treatment while, the high values of total Annual effective dose equivalent (AEDE) diminished its use for either ceramic or glass industries.


INTRODUCTION
Granitoides are the major source of fluxes, after albitites, having fulfilled about 19% of the overall ceramic demand in the period 1970-2015 [1].Alkali feldspars are the primary raw minerals used in the ceramic and glass industries.More than 70 nations have feldspar economic reserves, and more than 50 countries currently supply the majority of the world's feldspar production, which in 2006, 20 Mt of feldspar, 1.4 Mt of nepheline syenite, and 1.4 Mt of aplite, phonolite, and China stone [2].Egypt was one of many nations with feldspar reserves.In 2022, some 400,000 metric tons of feldspar were produced in mines all over Egypt, [3].
Over 90% of all material produced is used in the ceramics and glass industries, which also use feldspar minerals.The production of glass products uses more than 70% of feldspar, while ceramics and other items use 30%.Izquierdo Pazo et al., [4] shown that the low rate and balanced melting of feldspar across the necessary temperature range makes it stand out.Owing to its assistance in the melting of clays and quartz, this is of almost significance for the production of both glass and ceramics.In terms of its chemical and physical qualities, feldspar must meet particular grade and specification requirements for use in the ceramic and glass industries [5].Sinai [6][7][8] and the Eastern Desert [9][10] worked on the granite.The overall output from Ras Mohamed, Sinai, Egypt over the period 1970-2015 was estimated by 3 million tons [1].The potential of yet unexploited granitoid sources appears to be outstanding in some areas, like the Egyptian Eastern Desert [11; 12, 13].
The present study characterizes the mineral composition and radiometric impact of the feldspar placer deposits of Umm Shaddad area, Eastern Desert, Egypt, to study their applicability to use in glass and ceramic industries.

Geology & Geological setting
Umm Shaddad area located west of Umm Gheig Lead Zinc Mine, at latitude 25 o 37' and 25 o 41' and longitude 34 o 19' and 34 o 24' (Fig. 1).It could be reached from umm Gheig through the desert road running to the west of Wadi Umm Gheig for about 20 Kilometer.General outline topography shows that the area is built up of a series of separated granitic masses in which the largest of them is Gabal Umm Shaddad of around 770m above the sea level.These basement rocks exposed in the area of study are mainly arranged starting from the oldest as metavolcanics, metagabbros, granpdiorites, younger gabbros, monzogrznites, syenogranites, alkaline granites and alkaline syenites.A geological map at scale 1:50000 for the study area were modified after [14] (Fig. 2).Granitoids associated to volcanic rocks with a basaltic composition can be found in the rocks of the Umm Shaddad district.[15].Sabet [16] discussed that the granitic intrusion of Umm Shaddad is oval shaped and tectonized xenolitic granitic masses, fine to coarse grain size usually porphyritic composed essentially of alkaline feldspars and quartz and minor amounts of chlorite, sphene, apatite, epidote, zircon and little iron oxides.Umm Shaddad granitic masses are a discordant with the enclosing metamorphic rocks, where the boundary is substantially concordant with the foliation of the metamorphic rocks, (Fig. 2 and Fig. 3).The red granites are sometimes crushed and tectonized to varies extents.Wadi Um Lassifa is the main wadi draining the high granitic hill ranges and peaks of G. Um

Methodology
Thirty-five samples were collected from four vertical sections to cover the studied placer deposit body.
The distance between the sections are about 100 meters; section one and two form the largest alluvial fans at the Northern side of Umm Shaddad granitic body, section three from small fan at the same side.These three sections represent Khore Umm Shaddad alluvium sediments.While, section four collected from the fan at the South side of Umm Shaddad granitic body.The samples from each vertical section were taken from the base to the top every 25 cm.Section number one yielded ten samples., 6 samples from section no.two, 4 samples from section no.three and 15 samples from section no.four (Fig. 4a).All the placer deposits showing several cycles of sedimentation and finning upward, (Fig. 4b).All of the samples underwent mechanical analysis fractionate the sediments into 7 grain sizes and size was investigated by binuclear microscope to identify the mineralogical composition and the relative abundance of minerals to each other.
The mineralogical composition was determined using X-ray diffractometer (PW3710, in the Egyptian Nuclear Material Authority).Chemical analysis was done on seven selected samples (placer feldspar) to measure the major oxides which were done in Acme Labs (Toronto, Canada) by using ICP-MS method (is the analytical technique that uses an Inductively Coupled Plasma to ionize the sample, which provides a lower detection limit down to ppt).Twenty-three samples were chosen to represent the four vertical sections at Umm Shaddad area to evaluate the radiometric effect.After being filled and tightly sealed, cylindrical cans made of plastic with a 212 cm2 volume, 9.5 cm diameter, and 3 cm height were left for more than 30 days to gather free radon and reach radioactive equilibrium before being counted with a -ray spectrometer and then subjected to laboratory tests at the Egyptian Nuclear Material Authority to determine the content of (U, Th, Ra and K) as eU, eTh, Ra, and K%.

A.
B.

A-Mechanical analysis and mineralogical identification:
A representative amount of minerals in sand size (nearly about 0.1 gm, about 700-1000 grains) took by quartering from each sample and sprinkled on a glass slide, to be fixed under the was investigated under the binuclear stereomicroscope, and the weight percent of each mineral in the different samples was calculated.
This method reveal that the studied samples composed of quartz, feldspars, ferromagnesian minerals (mica) and opaque minerals.The percentage of minerals composition different from sample to another.In which the feldspars comprise the essential mineral which range from 56.5% to 88.6% followed by quartz, which constitute the range of composition from 8.1% to 31.32% and the ferromagnesian and opaque minerals ranged in composition from1.17% to 19.6%.

4.1.2.B-X-Ray Diffraction analysis
The composition of the minerals was established using X-ray diffractometer (PW3710) for four samples.
Each sample is a representative for each vertical section.These analyses revealed that the mineralogical compositions are anorthoclase, quartz, phlogopite, hematite, kaolinite (Fig. 5) and are listed in Table 1.

4.1.3.C-Chemical composition of Um Shaddad feldspar
Estimation of feldspar deposits at Wadi Umm Shaddad was performed using 35 samples from the four trenches.Chemical analyses were done to selected 7 samples of the raw feldspar to represent the four trenches and are represented at

Evaluation of the radiometric effect of the Raw feldspar of Umm Shaddad
Twenty-three samples were selected to represent the four trenches at Umm Shaddad area to evaluate the radiometric effect.The concentrations of natural radioactive elements determined in the collected samples are listed in Table 5.

The Conversion of ground radiometric measurements to specific activity
The value of K expressed in percent and values of eU, eTh, and Ra expressed in ppm were converted to activity concentrations (Bq/Kg) by using the conversion factors given by the International Atomic Energy Agency (1979).

Gamma activity index, I γ
The following equation [21] was used to determine I γ index: The amounts of 238U, 232Th, and 40K, respectively, are expressed as A , A Th , and A K in Bq/kg unit.This formula is based on the observation that radionuclides contribute to external radiation in proportion to their individual exposure rate constants, i.e., 40 K: 238 U: 232 Th = 1: 10: 15.This method calculates an index of gamma irradiation using the total of three distinct activity quotients, with the denominators selected to reflect the distinct exposure rate and provide a sum of one.According to Tzortzis [21], I γ values ranged from 0.9 to 1.2, with an average value of 1.04 Bq/kg for the samples under study (Table 7).The average values of the analyzed samples' gamma activity index are below the permissible value (2).The findings also showed that the analyzed rock samples had gamma indices I γ > 1 that correspond to dose rates less than 1 mSv/y (EC, 1999), which is thought to be the lowest value of dosage rate in air that is safe for the general population [22,23].

Alpha Activity index, I α
Radon descendants release radioactive alpha particles as they decompose, which adhere to aerosols, dust, and other airborne particles.The alpha particles from radon progeny that are deposited on the cells lining our airways after inhalation can damage DNA and perhaps cause lung cancer.The alpha index (I α ) [23; 24; 25] was used to evaluate the extra alpha radiation brought on by radon inhalation from building materials.
The following is its definition: I α values varied from 0.4 to 0.74 for the samples that were tested, with an average value of 0.5 Bq/kg (Table 7).It is evident that the alpha activity index values below the permitted level.Therefore, it can be claimed that the risk of radon inhalation from structures made of these materials is so low that their usage in building construction should be limited.

External hazard index, H ex
The external risk brought on by gamma radiation emissions is measured using the external hazard index (H ex ).With the help of the following equation, it was calculated: A U , A Th , and A K are the specific activity of 238 U, 232 Th, and 40 K, in Bq/kg, respectively, and H ex is the external hazard index.By assuming that the external hazard index's maximum permissible value i. e. equal to 1 corresponding to Ra eq 's upper bound (370 Bq/kg), the external hazard index can be calculated from the Ra eq expression.For the radiation danger from construction materials to be insignificant, the value of this index must be lower than unity [30].The highest value of Ra eq must be less than 370 Bq/kg in order for H ex to have a maximum value that is less than unity.The values of H ex varied from 0.66 to 0.87, with an average value of 0.72 Bq/kg for the samples under study (Table 7).It's acceptable value.

Internal hazard index, H in
The internal exposure to 222 Rn and its radioactive offspring is managed by the internal hazard index (H in ).
The following equation [24; 26] yields it: The conc. of 238 U, 232 Th, and 40 K in Bq/kg are denoted as A U , A Th , and A K , respectively.The value of H in will be less than 1 if the maximum uranium concentration in the study samples is half of the typical permitted limit H in should be less than unity for a material to be used safely in the construction of a home.For the examined rock, values of H in ranged from 0.89 to 1.26, with an average value of 1 Bq/kg (Table 7).It's acceptable value.The gamma activity concentration index I γ was calculated from the following equation [21]: Where, D: Absorbed Dose (nG/yh); 1.4: Population weighted value, because the indoor exposures are 40% greater than the outdoor exposures; 8760 (h/y): Time of hours per one year; 0.8: Occupancy factor for indoor (5/24) and 0.7: Conversion Coefficient for adult from absorbed dose to effective dose (Sv/Gy -1 ).

Absorbed Dose
According to [18], the absorbed dose rate was computed (Eq. 1) and its values are reported in

Annual effective dose equivalent (AEDE)
Gamma radiation from radionuclides in the 238 U and 232 Th series as well as from the presence of 40 K in collected samples are the main causes of external irradiation of the human body.Additionally, if earth materials are utilized during building, indoor gamma exposure which is primarily influenced by these elements-is naturally higher than outdoor exposure.The importance of indoor exposure increases when the length of tenancy is considered [23].
The conversion coefficient from absorbed dosage in air to effective dosage and the outdoor and indoor occupancy factors are utilized to estimate the annual effective doses, according to Senthilkumar and Narayanaswamy [31].The study of [23] states that the conversion coefficient between the absorbed dosage in the air and the effective dose received by humans is 0.7 Sv/Gy, and the occupancy factor for outdoor and indoor is, respectively, 0.2 and 0.8, meaning that, in terms of time spent indoors and outside.According to UNSCEAR [23], the annual effective dose equivalent (AEDE) in both outdoor and indoor air was calculated.Table 7 lists the computed AEDE indoor (Eq.2) and outdoor (Eq. 3) values.
The indoor and outdoor AEDE values range from 0.69 to 1.07 mSv/y and from 0.123 to 0.191 mSv/y, respectively (outdoor).The annual effective dose as a result is 0.48 mSv/y on average across the globe [22].

Total annual effective dose
The sum of AEDE, indoor (mSv/y) and AEDE, out (mSv/y) yields the total annual effective dose equivalent, Total (mSv/y).Total AEDE in the study samples varied from 0.82 to 1.261, with an average of 1.137.The annual effective dosage from external terrestrial radiation for the entire world's population is 0.5 mSv [23].

Conclusions
When compared to the commercial average for these economic industries, with the investigated feldspar placer deposit of the area under consideration.The chemical investigation revealed that Fe 2 O 3 had an average concentration of 2.48%, which is extremely high.The average K 2 O content in the samples was 4.77%, the average Al 2 O 3 content was 11.79% less than the commercial average for the ceramic and glass industries, the average Na 2 O content ranged from 2.54% to 3.33% less than the commercial average for the ceramic and glass industries, and the average SiO2 content was 74.16% less than the commercial average for the ceramic industries but higher than the commercial average for the glass industries.For the samples under study, Ra eq ranged from 193.2 to 243.98 with an average value of 225.48Bq/kg.The measured levels are below the permissible global threshold (370 Bq/kg).I γ values for the study samples varied from 0.9 to 1.2, with an average value of 1.04 Bq/kg.The gamma activity index average values of the examined samples fall below the allowable value (2).I α values for the samples under investigation ranged from 0.4 to 0.74 Bq/kg on average.Values for the alpha activity index are below the allowable range.H ex values for the samples that were evaluated varied from 0.66 to 0.87, with an average value of 0.72 Bq/kg, which is an acceptable value.The analyzed rock's H in values ranged from 0.89 to 1.26, with an average value that is acceptable being 1 Bq/kg.Wherever, the total annual effective dose equivalent total AEDE in the studied samples ranged from 0.82 to 1.261 with an average of 1.137, which exceeding the global effective dose from external terrestrial radiation for the entire population, which is 0.5 mSv/year.where the examined feldspars' effective dose exceeds the global effective dose.In conclusion, although the feldspar placers of Umm Shaddad area have suitable content of oxides after minor treatment while, the high values of total Annual effective dose equivalent (AEDE) diminished its use for either ceramic or glass industries.
Shaddad.This wadi has a general NE-SW trend.The granitic weathering products are concentrated in two tributaries wadies.These are Khore Umm Shaddad and Kab Ahmed.The main wadies and tributaries are covered by weathering products of granitic from the country rocks on their sides or upstream.Khore Um Shaddad runs in the west-east direction for about 2km.of average width of this Khore about 250m.The alluvium filling depth ranges from 1-4 m of elevation 294-273 m.

Figure 3 .
Figure 3. Photograph showing Umm Shaddad granite and the surrounding metamorphic rocks.

Figure 4 .
Figure 4. A. Photograph showing the sampling (white arrows).B. Photograph showing cyclisty and finning upward of placer deposits (yellow arrow) at Umm Shadad area, Egypt.

Figure 5 .
Figure 5.The mineralogical composition of a selected sample determined using X-ray diffractometer (PW3710).

Table 1 .
X-Ray Diffraction analysis for the selected samples.

Table 2 .
The chemical analysis for the samples represents that Fe 2 O 3 content varies from 2.03% to 2.99% with average of 2.48%, the extremely high amount of iron attributed to the mafic minerals at the original granite of Umm Shaddad.The K 2 O content in the analyzed samples rangeThe chemical analysis of Umm Shaddad raw feldspars was compared with the main ingredients of commercial ceramic and glass grade to evaluate the available placer feldspar deposit at Umm Shaddad for use in glass and ceramic industries, Table3 and Table 4; respectively.

Table 6
show the value of specific activity concentrations of natural radioelements.The activity conc. of 238 U, 232 Th, 226 Ra and 40 K ranged from 86.45 to 148.2 Bq/Kg, 32.48 to 48.7 Bq Kg -1 , 33.3 to 88.8 Bq Kg -1 and 1064.2 to 1677.68 Bq Kg -1 , respectively.The United Nations Scientific Committee's report on the consequences of atomic radiation [19] discussed the world average concentration of 238 U, 232 Th and 40 K are 35, 30 and 400 Bq/Kg; respectively.The activity concentration of radionuclides of our study, 232 Th, 238 U, 226 Ra and 40 K exceeds the global average value.

Evaluation of radiological hazard effects 4.4.1. Radium equivalent activity, Ra eq
[20]action of radioactive decay based on the presumption that 370 Bq/kg of 226 Ra, 259 Bq/kg of 232 Th, and 4810 Bq/ kg of 40 K provide the same γ ray dose rate, Ra eq is a weighted sum of the activity of the radionuclides226Ra,232Th, and 40 K.[20]Ra eq = A Ra ‫1+‬ .43ATh+‫‬ ‫770.0‬AKwhereA Ra , A Th and A K are the specific activities of 226 Ra, 232 Th and 40 K in Bq/ kg.Ra eq was estimated forthe collected rocks and are given in Table7.The Ra eq values varied from, 193.2 to 243.98 with average value 225.48Bq/kg for studied samples.The gained results are lower than the accepted global standards (370 Bq/kg).

Table 6 . The values of specific activity concentrations of natural radioelements.
The activity concentration of a sample containing 1.0 ppm of 238 U is equivalent to 12.35 BqKg -1 , 1.0 ppm by weight of232Th is equivalent to 4.06 Bq Kg -1 , 1.0 ppm of226Ra is equivalent to 11.1 Bq Kg -1 , and 1% of 40 K is equivalent to 313 Bq Kg -1 . *

Table 7 . The values of Radium equivalent activity (Ra eq ), Gamma activity level (I), activity index (Iα), hazard indices (Hex and Hin) absorbed dose rate, outdoor, indoor and total external effective dose in (mSv/y) of the study samples.
[19]radium equivalent activity Ra eq is a weighted sum of activities of the 226 Ra, 232 Th and 40 K radionuclides based on the assumption that 370 Bq/ kg of 226 Ra, 259 Bq/ kg of 32 Th and 4810 Bq/ kg of 40 K produce the same gamma ray dose rate[19] €

Table 7 .
[23]absorbed dose rate is defined as the quantity of energy in a unit mass in human tissues or organs.havingamean value of 140.853 nG/h, the computed values of the absorbed dosage varied from 101.8 to 156.01 nG/h.It exceeds the global average of 60 nG/h[23].