studies of glass sands occurring around shankargarh, district -...

Journal of Scientific & Industrial Research

Vol. 62, September 2003, pp 931-943

Studies of Glass Sands Occurring Around Shankargarh, District - Allahabad with Reference to its Economic Viability

Ajai Srivastava', R N Tiwari, Diwakar Mishra and Kshitij Mohan

Department of Geology, Banaras Hindu University, Varanasi 221 005

Received: 22 July 2002; revised received: 25 April 2003; accepted: 14 May 2003

The present paper deals with the glass sands occurring around Shankargarh, district Allahabad. The sands in the area are predominantly whitish. However, other colours viz., pink, light yellow, yellow, brown, and red are also commonly found. More than 60 samples representing the vertical and lateral variations of the lithological units were collected from different parts of the area for grai n size, mineralogi cal and geochemical analyses. The grain size analysis reveals that the majority of the grains are rounded, coarse to fine size grade, well sorted , finely skewed and platykurtic. Mineralogical study of the selected glass sand samples shows the presence of light minerals, i.e. , quartz, mica, and chert and heavies-rutile, staurolite, tourmaline, and zircon. Opaques include magnetite and ilmenite. Geochemical analysis of these sands reveals a variation in Si02 inbetween 97 per cent and 99.0 I per cent , whereas Fe20 ) from 0.14 per cent to 1.41 per cent and AI20 J 0.12 to 1.89 per cent. The percentage of iron decreases with the increase of depth, thereby at the base white glass sand of purest variety is met with. Impurities in the form of iron oxide, glistening specks of mica, etc., have been observed in the glass sands. By treatment and beneficiation , iron, and aluminium contents of the glass sands of the area can be reduced for the purpose of making colourless glass. These sands can also be used for making the different types of glass, i.e., lime glass, lead glass, and sili cate glass. The glass sands in the area have been found under thin cover of soil with a gentle ground slope. This has provided more time and opportunity for the rain water to percolate through and thereby facilitate the disintegration of the parent rock in the dry summer season .

Key words: Glass sands, Silicate glass, Economic viabi lity

Introduction

The paper overviews the glass sands of the Shankargarh, di strict Allahabad. The area under investigation lies between latitude 25°10' to 25°15' N and longitude 81 °35' to 81 °40, E and is covered by the Survey of India toposheet no. 63 G/12; covering an area of 30 sq km. The area can be approached either by railway or road. It is about 45 km by road from Allahabad in the direction SSE along Allahabad" Banda road . Shankargarh is a railway junction on the Varanasi-Bombay section of the Northern Railway. From Shankargarh, there is a metalled road connecting Sheorajpur, lubai , and Agartalla hills, which mns through the study area.

The general topography of the area is mgged. The rocks are exposed on the isolated hillocks of lubai , Agartalla, Lakhanpur and Ramna. There are small isolated hillocks namely lubai, Agar, Khandi,

Author for correspondence E-mail: [email protected]

Khatkari, and Baisa. The highest altitude is 572' towards NNW of Shankargarh railway station. The whole area is drained by numerous seasonal nalas. There is one big nala, which passes through Gondh , Gathwa and meets a pond near the fort at the foot of Agartalla hill. The nalas are full of water during the rainy season and dry throughout the remaining part of the year except one which is perennial.

Geology of the Area

Geologically the area under study is a part of Kaimur Group of Vindhyan basin) . The Kaimur Group comprises six dominantly siliciclastic formations, i.e., Sasaram sandstone, Susnai breccia, Ghaghar sandstone, Bijoygarh shale, Mangesar formation and Dhandraul sandstone overlying the Semri group. Most earlier workers considered the Kaimur/Semri boundary to be conformable on the criteria that the Rohtas Limestone (the topmost unit of the Semri group) passes to overlying Sasaram sandstones (lowermost unit of the Kaimur group) without dip. Krishnan and Swaminath2 have

932 J SCI IND RES VOL 62 SEPTEMBER 2003

suggested an unconformable relationship between thetwo. The upper contact of the Kaimur group with theyounger Rewa group is unconformable.

In the investigated area, there occurs an isolateddetached hillock consisting of Dhandraul sandstone.The total thickness of the Kaimur group varies from181-365 metre consisting mainly of sandstone withsubordinate amount of shale and breccia}. TheDhandraul sandstones are exposed at almost all thehillocks of the area. The general strike direction of thearea is NW -SE and the rocks have more or less gentledip. The Dhandraul sandstones are exposed at almostall the hillocks of the area. The ripple marks arepresent at the top of the Dhandraul sandstones in theAgar pahar. The cross-beddings are seen in therailway cuttings, stone quarries and also in the sandquarries. These structures are prominent in Jubai Hill,Agartalla and Lakhanpur. Some rain pits are alsoobserved in the Dhandraul sandstone on the top of theAgar and Jubai hillocks.

Occurrence of Glass-sands in the AreaThe sands found in the Shankagarh area are of

various colours viz., white, yellow, pink, brown, andred. These are coarse to fine grained, havingimpurities in the form of iron oxide. The red sands arefound at the top of the hillock and brown, yellow,pink and white follow in the descending order. Glasssands in the area occur in the Agartalla pahar, Rarnnapahar and Bargari. The sandstones in the area occurunder a comparatively thin covering of soil andground is of gentle slope, which have become friableup to a considerable depth, possibly through theagency of rain water percolating into the soil andleaching out parts of the iron and loosening the silicacement that binds the sandstone grains. However,lateritic concretions are met to conceal the sandstonebeds at some places. In the dry summer season, ironoxide is drawn up by capillary action to form a thincrust on the top of the sandstone. By an alteraterepitition of the process the quartz grains are coatedwith the iron oxide, which is a major fraction of theheavies. The sandstones are compact and dirty whiteor light pink in colour. After removing the soil, if anythe sandstones are broken up into small pieces.Several layers are above the other. Little work hasbeen carried out on the study of glass sands of thearea. However, Ram et al.4 gave a glimpse of glasssands and associated rocks occurring in the area.Some details are found from the work of Mishra",Singh'' and Singh and Singh",

SamplingThe present work comprises a geological study

of Shankargarh area mainly around Agartalla, Jubai,Rarnna, and Lakhanpur hillocks. The lithounitspresent in the area were studied in the laboratory forgrain-size, mineralogical and geochemical variationsof the various lithounits. The glass sands have beenstudied in terms of their economic significance andutilisation in glass industry. More than 60 samplesrepresenting the vertical and lateral variations of thelithological units were collected from different partsof the area. The samples subjected to grain-size,mineralogical and geochemical analyses are shown inthe Figure 1 (Location map).

Materials and MethodsFrom the large number of samples collected,

representative samples were selected for the detailedlaboratory study. The samples were dried andsubjected to quarter and coning, to have its truerepresentative fraction. These samples were subjectedto size analysis by sieving method using Retschsieving machine and ASTM (American Society forTesting Materials) sieve sets at Y2 <jl interval. For theidentification of mineral constituents of glass sands,high power Nikon Petrological Microscope Fx-35Awas used. The rapid spectrochemical method werefollowed for the analysis of the major elementslO

•".

Laboratory Analyses and ResultsA brief account of grain size behaviour,

petrological observation, and distribution of majoroxides are given subsequently:

Grain Size AnalysisFor the purpose of grain size analysis the

representative samples of the Dhandraul sandstoneshave been disintegrated. For better disintegration thesamples rich in ferruginous cement, were treated withhydrogen peroxide and hydrochloric acid. The grainsize analysis was done by sieving method usingASTM sieve sets with mesh numbers 25, 35, 45, 60,80, 120, 170, 230 and 325. The grain size frequencydistributions are shown in the Table 1.

The frequency curves (Figure 2) show that mostof samples are unimodel in nature. The cumulativecurves drawn on the arithmetic probability graphpaper (Figure 3) were plotted on the basis ofcumulative weight percentage (Table 2) and theyexhibit that the saltation and suspension dominate thesize population, although a few shows the presence of

SRIV ASTA V A e/ al.: STUDIES OF GLASS SANDS 933

'2~

Berul • . f/oil"'!Et. ___ ----..-----

Kunrhl ·0

2 ':<>!d.' .... --'-_ .... 81°·35

Figure 1- Locati on map of the area showing sampling sites

SI No. Sample

2

3

4

5

6

7

8

9

10

II

12

13

14

IS

16

17

18

19

20

No. I ASTM • .. Mesh size in <!> •

5

6

7

8

10

11

12

13

14

15

16

17

26

28

29

59

60

61

62

63

Table 1- Weight percentage of different grain size of Shankargarh/Pratappur sandstones

25 0.5

0.375

0.301

0.280

0.76 1

0.3 13

0.122

0.496

0.035

0.024

0.014

0.370

0.019

0.014

0.102

0.103

0. 105

0.345

0.032

0.032

0.000

Mesh size (ASTM )I <!> value (equivalent)

35 1.0

1.745

1.645

1.486

3.7 17

2.651

2.402

4.005

1.347

0.570

0.452

0.79 1

0.909

0.453

45 1. 5

5.889

4.349

2.977

4.286

1.521

4.594

2.668

1.40

0.624

0.492

0.552

1.104

0.509

0.981 0.802

0.675 1.280

3 1.249 28.238

10.275 39.759

1.84! !8.508

0.121 0.910

0.076 10.499

60 2.0

29 .111

22.160

15.996

18.6 14

9.682

73.90

36.758

20.690

16.422

21.509

21.151

48.984

13.884

15.656

30.7 14

23 .783

33 .938

21.785

15.0 15

46.537

80 2.5

21.152

18.256

14.569

2 1.752

3 1.269

9.897

20.154

38.204

40.296

35.895

29.352

30.24 1

40.185

40.263

35 .249

8.258

7.263

26.237

38.267

17.178

120 3.0

23.562

15 .920

15.581

14.968

26.246

6.721

13.847

28.858

31.7 14

29.758

33.242

14.824

33 .838

29.126

19.966

7.504

6.02 1

28 .33 1

38.878

20.908

170 3.5

8.541

19.095

21.727

13.286

9.447

0.833

9. 144

4.658

6.06

5.967

5. 144

1.585

5.936

6.867

6.169

0.515

1.348

2.477

4.917

3.784

230 4 .0

6.920

16.488

22.998

20.867

13.354

0.735

8.065

2.996

2.845

4.205

7.225

0.9 17

3.077

3.897

3. 169

0.206

0. 161

0.5l0

0.372

0.20

325 4.5

1.354

1.195

2. 173

0.660

2.946

0.094

2.464

0.687

0.580

0.7 18

1.218

0.123

0.6 17

0.98 1

0.755

0.068

0. 151

0.138

0.085

0.031

325 Finer than

4.5

0.784

0.077

0.647

0.046

1.125

0 .048

O. 988

0.268

0.250

0.204

0 .184

0.83

0.23 1

0.351

0 .297

0.034

0.109

0.03l

0.031

0.033

Total

99.433

99.486

98.434

98.957

98.554

99.346

98.589

99. 143

99.385

99.2 14

99.229

99.536

98.744

99.026

98.377

99.960

99.370

99.890

98.628

99.246

\0 W ~

C/)

Q

z I::)

;;0 tTl C/)

< o r 0'\ IV

C/)

tTl

~ 3: c::l tTl ;;0 IV

25 ....,

SI Mesh Class No size interval

(in <I>

unit) 5 6 7 8

Table 2- Cumulative frequency per cent of sandstones obtained from size distribution

Sample Number

10 II 12 13 14 15 16 17 26 28 29 59 60 61 62 63

25 0.5 0.375 0.301 0.280 0.761 0.313 0.1 22 0.496 0.035 0.024 0.014 0.370 0.019 0.014 0.102 0.103 0.105 0.345 0.032 0.032 0.000

2 35 1.0 2.120 1.946 1.766 4.478 2.964 2.524 4.501 1.382 0.594 0.466 1.161 0.928 0.467 1.083 0.778 31.354 10.620 1.873 0.153 0.076

3 45 1.5 8.009 6.295 4.743 8.764 4.485 7.118 7.1 69 2.782 1.2 18 0.958 1.71 3 2.032 0.976 1. 885 2.058 59.59250.37920.381 1.063 10.575

4 60 2.0 37.12028.45520.73927.378 14.167 81.01843 .92723 .472 17.64022.46722.864 51.01614.86017.54132.772 83.375 84.317 42.16616.078 57.112

5 80 2.5 58.272 46.71 1 35.30849.13045.43690.9 15 64.08161.67657.936 58.362 52.2 16 81.257 55.045 57.80468.02191.63391.58068.40354.34574.290

6 120 3.0 8 1. 834 62.631 50.889 64.098 71.682 97.636 77.928 90.534 89.650 88.120 85.458 96.08 1 88.883 86.930 87.987 99.137 97.601 96.734 93 .223 95. 198

7 170 3.5 90.37581.72672.6 1677.38481.12998.46987.072 95.192 95.710 94.087 90.602 97.666 94.819 93 .797 94.156 99.652 98.949 99.2 11 98.14098.982

8 230 4.0 97.29598 .21495.61498.25194.48399.20495.13798.188 98.555 98.292 97.827 98.583 97.896 97.694 97.32599.85899. 110 99.72 1 98.51299.182

9 325 4.5 98.649 99.409 97.787 98.911 97.429 99.298 97.60 I 98.875 99.135 99.010 99.045 98.706 98.513 98.675 98.080 99.926 99.26 1 99.859 98.597 99.213

10 325 4.5 99.433 99.486 98.434 98.957 98 .554 99.346 98.589 99.143 99.385 99.214 99.229 99.536 98.744 99.026 98.377 99.960 99.370 99.890 98.628 99.246

en ~ < » en -l » < » ~

~ en -l c: o tTl en o '"I1 Cl r » en en en » z o en

\0 W VI


35 ----- ---------

30

<f!. 25

i >- 20 u c ~ 15 0" QI u: 10

5

Sample No.

o ~~-------------~ _______ ~~.~

45

40

35 ~ o

~ 30

>- 25 U

; 20 j

0" e 15 u.

10

5

0.5

0.5

1.5 2 2.5 3 3.5 4 4.5 Finer

Size grade in Phi (~)

than 4.5

_. __ ... _-, Sample No. I

--'-12

----13 -.-14

1.5 2 2.5 3 3.5 4 4 5 Finer

Size grade in Phi (¢)

than 4.5

I

45 - ... . - --.... -.--....... .. . -- .- -- .. - - --- --.- ... --.. ---

40

<f!. 35

... 30 ~ >- 25 u ; 20 j

0" 15 e u. 10

5

Sample No. --1-26 ___ 28

-.11.- 29

""""*- 59

o LifI~.,.L----~i--*""~~tt_J 0 .5 1.5 2 2.5 3 3.5 4 4.5 Finer

Size grade In Phi ($)

than 4.5

80 r-~-------------------------.

70

~ 60 o

'i 50

>-g 40 Q) j 0" 30 e

LL 20 .

10

60

50

<f!. ~ 40

>-g 30 Q) ::3

g 20 ... LL

10

50

45

<f!. 40

..: 35

~ 30 >g 25

~ 20 0" e 15

LL 10

5

0.5

05

Sample No.

1.5 2 2.5 3 3.5 4 4.5 Finer

Size grade in Phi ($)

Sample No.

than 4.5

. I

1.5 2 2.5 3 3.5 4 4.5 Finer

Size grade in Phi (4))

Sample No.

~60 __ 61

-.-62 -~63

than 4.5

o~~ __ ~---~-~~~~~~ 0.5 1.5 2 2.5 3 3.5 4 4.5 Finer

Size grade in Phi (4))

than 4.5

Figure 2 - Frequency curves of Dhandraul sandstone of Shankargarh area

91.11 1t.1~ 19.9 11.8 99.S It

r- 19 ~ 95 96

U 90

·ffi a.c 0.. 75 eo r- 70 1: 60 (!) 50 - 40 ~ 25 30

!!! 1620

g 10

~ 5 i :::> ' 1 U 0.5

0.2 0.1 0.05

~--6 ' -5

0.02 +1 -..-'--r-~-,--.---...,

H." tUS H ,' H.I ".!

" r- H ~ 95" U 90 a:: w 14

10 ~ 75 70 a 60 _so ~ ... ;g w 25 20 > ,.

~ 5 'i :::> 1 U U

0,2 0.1

1 ·2 3 4 5 • DIAMETER IN PHI UNITS

0.05 0.02 +1-..,---.-.-----,--,.---,

1 2 3 ~ 5 6 DIAMETER IN PHI UNITS

lUI IUS .1.1 It.I 11.5 II

r- H ~ 95" U 90

ffia.c . 0.. 75 10 r- 70 '1: 60 (!)so iii 40 ~ 30 W 25 20 >1$

i 5 'i :::> 1 U 0.5

0.2 0.1 0.05

~-.• -1

0.02 tl-r--r---r--,--'-,.--,

" .N -:.~: H.' " .5.·

r- il ~ 95 N U 90 ffia.c 0.. 75 10 r- 70 1: 60 (!)so iii 40

~ 25 30 W 1620 ~ .

i 5 'i :::> 1 U 0.5 ·

. 0,2 0.1

1 2 3 4 5 6

DIAMETER IN PHI UNITS

--~ --'26

8:g~ +1 -r--r---;--,--,--, : 1 2 3 4 5. &

DIAMETER INPHI'UNITS

lUI · ... 11.

19.' .... 19.5

" r- n ~ 95 II U 90 a: wa.c eo 0.. 75

70,

~ 60 (!)so iii 40 ~. 2$ 30 ~1620

i 5 'i :::> 1 U 0.5

-;. ... f -JO

rJ I

I

I"~'

D .~ , ~ I £05 _ 0.02 t--,---r-,.---r---,--

)'.N H .IS " .. " .. ·H .S H

r- " . ~ 95" U to ffia.c 0.. 75 10 r- 70 I 60 .

. (!) 50 iii 40 ~ 25 30 ~ 16 20

1=10 :5 :::> ~ :::> U

5 4

~ 1

0.5

1 23 4 5 • DIAMETER IN PHI UNITS

' , .J""

---59 1/' -29/

I I

I

I I • •

t I ·

o. ~ I , , .

I:g~ 1 1 1 1 1 I . 1

. · 1 2 3 4 5 6 DlAMETERIN PHI UNITS

It." .11.15 91.' H .I 99.5 tt

r- . n ~ 95 H U 90 a: W 84

10 0.. 7570

~ 60 (!)so - 40 ~~5 30

~ 1620

i 5 'i :::>. 1 U 0.5

0.2 0.1

-13 ·~12 .

8:8f tl-r--r---r---,--,-...,

H .N -:.., H.' .", .,

r- I ffi I~ N U · to a: u ~ 75'0 r- 70 1: 60 . (!)so iii 40

~ 25 30

~ 1620

1= 10

:5 5 4 ~. ~ :::> 1 U 0.5

1 2 3· 4 5 ,


0.2 . 0.1

0.05 0.02 I 1 1 1 1 1 1

0123456


Figure 3 - Cu mul ative curves of Dhandraul sandstone of Shankargarh area

H." ,.,. H.' H .5

~ U ~ 95" U to ffia.c 0.. 75~ ~ ~' ~ (!),So iii 40

~ 25 30

~ 1. 2~ g 5 10

~ t :::> 1 U U

0.2 0.1

-14 ~~·15

0.05 _ 0.02 1 1 1 1 1 1 I .

1 2 3 · 4 5 • ..

DiAMETER IN PHI UNITS

I!I.N

\1-U-.l-"-~~

r- . " l-62 ifi IS N

~ to wU 0.. 75 10 'r- 70 · I 10 ~so W 40 3: 25 30

~ 1. 20

3 '0

~ 5 t a 1 0.5

0.2

£J5 0.02 1 ~ .. ~-:~---....:.:..-

1 2 3 4 5 • DIAMETER IN PHI UNITS

en ;;>::l

< » en -l » < » ~

~ en

~ Cl @ en o '"I1 Cl r » en en en » z Cl en

\0 W -...)


population belonging to traction mode. The saltationpopulation consists of 80 to 95 per cent of the totalload. The suspension population comprises 2 to 5 percent of distribution. The size range (from 0.5 <1> to 3.5<1» in the saltation population strongly suggests asorting intermediate between deposits formed by thesuspension and those produced by wave or oscillatorycurrents. The different percentile values obtained fromcumulative curves are tabulated in Table 3. The grainsize parameters- mean, standard deviation, skewness,and kurtosis were computed as suggested by Folk andWardl2. The formulae used for calculations are givenbelow:

M = ¢16+¢50+¢84,z 3

¢84-¢16 ¢95-¢50'1 = + ,

4 6.6

S ¢84+¢16-2¢50 ¢95+¢5-2¢50K( = 2(¢84-¢]6) + 2(¢95-¢5) ,

K = ¢95-¢5G 2.44(¢75-¢25)

The values of grain size parameters are shown inTable 4. The Dhandraul sandstones are medium (1.00<1> to 1.99 <1» to fine (2.00 <1> to 2.99 <1» sands, however,fine sands are prominent. The Median (Md <1» values,a measure of central tendency, i.e., 50th percentile,range from 1.30 <1> to 3.00 <1>. The higher range of sizevariation is attributed to more fluctuation indepositing medium. The sandstones are very wellsorted (i.e. <0.35 <1» to moderately sorted (i.e. 0.71 to1.00 <1». Maximum number of samples fall in thecategory of well sorted (i.e. 0.35 to 0.50 <1» followedby moderately sorted (i.e. 0.71 to 1.00 <1» andmoderately well sorted (i.e. 0.50 to 0.7] <1». The valueof skewness, a measure of symmetry around mean,suggests that the Dhandraul sandstones are negativelyskewed to positively skewed. The sandstones belongto platykurtic (i.e. 0.67 to 0.90 <1» to very leptokurtic(i.e. 1.50 to 3.00 <1». 65 per cent samples have kurtosisvalue greater than unity and thereby indicative of agreater fluctuation of the depositing medium.

Table 3 - Percentile values in <I>units obtainable from cumulative curves

SI No. Sample No. <1>5 <1>16 <1>25 <1>50 <1>75 $84 <1>95

5 1.30 1.73 1.90 2.63 3.35 3.60 3.80

2 6 1.40 1.70 1.80 2.30 2.80 3.20 3.80

3 7 1.60 1.95 2.20 3.00 3.60 3.70 4.00

4 8 1.10 1.73 1.90 2.65 3.40 3.63 3.87

5 10 1.60 2.10 2.30 2.68 3.20 3.60 4.10

6 II 1.40 1.70 1.75 1.87 1.95 2.10 2.64

7 12 l.I0 1.94 1.90 2.10 2.80 3.20 4.00

8 13 1.70 1.95 2.00 2.25 2.55 2.70 3.50

9 14 1.90 2.00 2.15 2.40 2.65 2.80 3.30

10 15 1.75 1.90 2.10 2.40 2.65 2.80 3.50

11 16 1.55 1.80 1.95 2.30 2.65 2.90 3.70

12 17 1.60 1.75 1.80 2.00 2.40 2.60 2.90

13 26 1.80 2.00 2.15 2.45 2.70 2.90 3.50

14 28 1.75 1.95 2.10 2.40 2.70 2.80 3.60

15 29 1.60 1.80 1.90 2.20 2.50 2.70 3.50

16 59 0.70 2.85 0.90 1.30 1.70 2.00 2.40

17 60 0.90 1.10 1.20 1.50 1.75 1.90 2.50

18 61 1.20 1.40 1.70 2.10 2.40 2.55 2.80

19 62 1.80 2.00 2.10 2.30 2.60 2.73 3.10

20 63 1.45 1.60 1.70 1.85 2.26 2.50 2.90

SRI V ASTA V A el af.: STUDIES OF GLASS SANDS 939

Mineralogy

Bulk samples were reduced to an approximate size by coning and quartering and 10 g of the samples were taken for heavy and light mineral s separation. Clay fraction was removed by repeated decantation . Sand-sized detrital grains were cleaned with acetic ac id. Samples having a thick coating of ferruginous matter were treated with dilute solution of hydrochloric acid and stannous chloride. The cleaned samples were washed with di stilled water and dried in the oven at low temperature. Heavy and light mineral s separation were carried out by routine bromoform method .

The percentages of quartz-grains are 90-95 per cent. Heavies, i.e., rutile, Zircon, ilmenite, and tourmaline have been commonly observed. Opaques

include magnetite and ilmenite. The quartz grains are characterised by the inclusion of iron oxide and fin e silt. Broadly two types of contacts between detrital quartz grains have been noticed :

(i) Contact between grains showing secondary silica, and

(ii ) Contact between graIns with secondary overgrowth.

The frequency of the heavies in the vertical section of the Dhandraul quartz-arenite is presented in the Table 5. The heavies like, tourmaline and zircon compnse a major per cent of total heavies. Tourmaline dominates In the coarser fracti on but decreases from lower to upper part of the vertical section, whereas zircon increases towards upper part

Table 4 - Grain size parameters of size frequency distribution of sandstones (in <1> unit )

SINo

2

3

4

5

6

7

8

9

10

II

12

13

14

15

16

17

18

19

20

Sample No

5

6

7

8

10

II

12

13

14

15

16

17

26

28

29

59

60

6 1

62

63

Mean size (Mz)

2.65

2.40

2.88

2.67

2.79

1.89

2.41

2.30

2.40

2.36

2.33

2.12

2.45

2.38

2.23

1.38

1.50

2.00

2.34

1.98

Median (Md)

2.63

2.30

3.00

2.65

2.68

1.87

2.10

2.25

2.40

2.40

2.30

2.00

2.45

2.40

2.20

1.30

1.50

2. 10

2.30

1. 85

Standard deviation (0"1 )

0 .84

0.73

0 .80

0.89

0.75

0.28

0 .75

0.46

0.41

0.49

0 .60

0.40

0.48

0.49

0.51

0.54

0.44

0.53

0 .38

0.44

Skewness (S K I)

-0.0 13

0.225

-0. 183

-0.040

0 .181

0.195

0.528

0.294

0.142

0.073

0 . 196

0.397

0.117

0 . 119

0 .239

0.255

0 .125

-0.170

0 .204

0.446

Kurtosis KG

0.70

0.98

0 .70

0.75

1.1 4

2.54

1.32

1.34

1.14

1.30

1.26

0.89

1.26

1.26

1.29

0.87

1.1 9

0.94

1.06

1.06


Table 5 - Frequency percentage of common heavy mineral in vertical section (60-120 mesh & 120-230 mesh)

Heavy mineral Sample Number

6 7 8 10 14 26Average

12.5 18.5 28.5 7.2 20.8 16.4 17.3Opaque

38.6 11.8 6.5 5.1 11.2 11.2 14.0

88.0 68.0 70.0 87.2 65.8 62.2 73.5Tourmaline

79.2 67.0 63.0 63.7 41.5 46.2 60.1

12.0 23.4 24.0 12.0 14.2 12.4 16.3Zircon

18.0 29.0 33.0 34.0 51.0 48.0 35.6

Staurolite0.8 20.0 19.6 13.4

3.0 1.7 6.5 4.3 5.1

8.6 6.0 5.8 6.8Garnet

0.4 0.7 0.55

Rutile2.8 1.0 0.3 1.4 1.1 1.32

of the section. On the other hand, other minerals, i.e.,garnet and rutile are somewhere present. Tourmalineoccurs in coarser fraction. Thus, the finer fractioncontains less percentage. The zircon is dominating inthe finer fraction than tourmaline in some section.Staurolite contains higher percentage in coarserfraction in some section amongst the heavies but theiroccurrence, in general, is not following an order.Occurrence of rutile and garnet is less but garnet ispresent in the coarser fraction.

The sandstones are white to purple in colour,massive, fine grained sand consisting of traces ofinterstitial clay minerals and layer of ferruginousmaterial at the uppermost part of the deposits. Thefriable quartz-arenites are used as glass-sand.Cementing materials are silicious and calcareous,sometimes ferruginous cement !S also seen. Thegrains of quartz are rounded to sub rounded, andoccasionally subangular having interlocking contact.

Geochemical AnalysisFor geochemical analysis the representative

samrles, twelve in number, were dried in the oven at100 -ISOoC and cooled to room temperature. Thesesamples were then crushed and powdered in an agatemortar up to 300 mesh using ethanol suitable for theanalytical purpose 10.11. The results are shown inTable 6. The analysis shows that Si02 generallyranges from 97-99 per cent, Fe20) 0.14-1.41 per centand Ah03 0.12-1.89 per cent. In few samples (i.e.

sample nos 5, 29 and 59), iron oxide is comparativelyhigh. These samples incidentally represent dirty whiteor yellow friable sandstones at the base of friable unit.

Economic ViabilityIn the area under study, deposits of Upper

Kaimur, i.e., Dhandraul sandstones are being quarriedat Agartalla, lubai Hills, and Lakhanpur. Thesedeposits are mostly friable in nature and easilyworkable. Glass sands in the area have a silica contentbetween 97-99.01 per cent. Impurities in the form ofiron oxide, i.e., particles of ferruginous materialsaround sand grains, glistening specks of mica, andclayey matter coated over the sand grains have beenfound. It may be stated that the glass sands havingsuch impurities is screened and washed coupled withthe chemical treatment, and electro-magneticseparation to remove all the deleterious constituentsfor its use in the glass industry. The tolerable amountof the impurities associated with the silica sandsdepends on the kinds of glass to be produced, e.g., foroptical glass, Fe203 content should be less than 0.015per cent, for flint glass it should be up to 0.040 percent, for window glass and containers (glass) andamber bottle glass it should not exceed 0.300 and1.000 per cent, respectively.

Indian standard specification for glass sands(Indian Standard - IS: 488-1953) delineates theamount of silica, iron oxide, titanium oxide, etc.,which are given in Table 7.

SRIV ASTA V A e/ at.: STUDIES OF GLASS SANDS 941

Table 6 - Chemical analysis of friable sandstone of Shankargarh

SI Sample No. Samples description Si02 Fe20 3 AI 20 3 Total No.

5 Dirty white friable sandstone 98.68 1.14 0.13 99.95

2 7 White fri able sandstone 99.01 0.14 0.55 99.70

3 II Semifriable white sandstone 98.15 0.56 1.12 99.83

4 13 Friable sandstone 98.56 0. 17 0.95 99.68

5 16 Semifriable sandstone 97.00 0.59 1.89 99.48

6 26 Dirty white compact to semi friable sandstone 98.35 0.17 1.1 5 99.67

7 29 Thinly laminated yellow fri able sandstone 97.62 0.83 1.47 99.92

8 59 Yellow friable sandstone 97.14 1.41 1.17 99.72

9 60 Yellow to white friable sandstone 98.48 0.28 0.89 99.65

10 6 1 Yellow semifriable sandstone 98.59 0. 15 0.96 99.70

II 62 Yellow to friable 98.98 0.23 0.57 99.78

12 63 White fri able sandstone 98.76 0 .1 6 0.95 99.87

Amount of constituent materials

Table 7 - Indian standard specification for glass sands

Grade I Grade 2 Grade 3

Silica (Si02), per cent min

Iron oxide (as Fe20 3), per cent max

Titanium oxide (Ti02), per cent max

Grain size- remaining as IS test sieve 100 (aperature 1,000 mi crons), per cent by wt

Grain size - remaining as IS test sieve 60 (aperature 592 microns), per cent by wt

Grain size pass ing th rough IS test sieve 12 (aperature 124 microns), per cent by wi

Moi sture, per cent by wt

Thus, keeping in view Si02 content (i .e . 97-99.0 1 per cent), glass sands of the area fall under the

category of Grade I . However, comparatively high

content of iron oxide in the glass sands collected from

lubai, Madanpur, and Bargari could be reduced by treatment, i.e. , washing and sieving. If two methods are made, we can use dirty white and ye llowish g lass sands of these areas for making colourless g lass . Light yellow sands of Ramna, Agar and other areas can be

used for making white bottles and general g lass-ware.

In Ramna, there occurs also a light pin k colour sands, which have low iron ox ide percentage but by

treatment these sands can be lIsed for manufac turing

whi te glass-ware. There are also two types of sand s, which are red and brown in colour. These sands may

97.5

0.05

0.10

Nil

1.0

5.0

5.0

95.0

0.12

0. 10

Nil

1.0

5.0

5.0

92.5

0.50

0.50

Nil

1.0

5.0

5.0

be used for making coloured glasses . Additionall y,

there is a scope to expand the ir utility to maintain or

increase the permeability of oil and gas bearing formations; as a filter in acid-proof cements, in

horticulture; as a filtration medium; and for ornamental purposes.

The grain size of the constituent raw materi al plays a significant role in the process of g lass making. If the size of the sands decreases below 40 to 60 ASTM (0.42-0.25 mrn) the me lting is acce lerated. A

good glass sands should have 70 to 90 per cent or even more of one grade preferably between the size

range of 0.25 to 0.5 mm l.1 . According ly, glass sand

deposit of lubai , containing 73 .9 per cent sands of one

s ize grade (0.25 to 0.5 mm), is suitable for making


colourless glass. Besides, deposits of Lakanpur andRamna areas might be considered good for makingcolourless glass. Glass sands found in Shankargarhare of pocket deposits thus the reserve could not beexactly estimated. They range in thickness from fewfeet to 60 ft and in places are very pure and so friablethat they can be pumped out as in Baragari and Goundareas. Glass sands of Shankargarh account for a lionshare in its production in the State of Uttar Pradesh.During the year 1999-2000, the production of 81,822 tvaluing Rs 56,83,000 was registered in the area asagainst 84,502 t valuing Rs 58,28,000 recorded fromthe state. Out of 11 mines situated in the state, 10mines are in the District Allahabad only. Theprincipal producer in the state is Silica Trading Co.,Allahabad'".

EpilogueThe Shankargarh deposit is medium to finely

grained, well sorted, cementing material beingsiliceous. Constituent quartz grains are angular tosubangular and are most dominating mineral (90-95per cent). Intergrowth of secondary silica is observed.Inclusion of iron oxide as an impurity is present. Thedeposit in the area occurs under a comparatively thincovering of soil. The depth of the soil seems to havesome relation with thickness of the friable quartzitezone. It is observed that greater the thickness of thesoil, greater the thickness of the glass sands. Thesands are found in the sequence as red glass-sand,brown glass sand, yellow glass sand, light yellowglass sand, pink glass sand, and white glass sand.

According to Indian Standard specification,Shankargarh glass sands can mainly be used formaking white glass and high grade domestic anddecorative glass. However, comparatively highcontent of iron oxide, present as an impurity, in theglass sands of Jubai, Madanpur, and Bargari could bereduced by treatment, i.e., washing and sieving. Ifthese methods are developed, we would be able to usedirty white and yellowish glass sands of these areasfor making colourless glass. Light yellow sands ofRamna and Agar areas could be used for makinggeneral glass-ware. With the help of these sands,several types of glasses viz., lime glass, lead glass,silicate glass, and optical glass could be made.Besides the sands of the area are most important forbuilding stone, milestone, road material, and other

similar purposes. Its other major use could be inmetallurgy (where silica is used as a refractory,fondry sand, flux, and as a source of silicon, for theproduction of silicon metal and ferrosilicon alloys), inthe electronics, chemical, and construction industries,and as a natural abrasive. The glass-sands of the areawas not given much attention with reference to itseconomic viability, therefore, an intensive field andlaboratory investigations are required for makingcolourless and high grade glasses economically.

ConclusionIt may be stated that the deposit of the area is

medium to fine grained, well sorted, occurring undera comparatively thin covering of soil. The glass sandsof the area are of pocket deposits so the reserve couldnot be exactly estimated. The glass sands are of •A'grade when viewed from context of silica per cent.These sands can chiefly be used for making highgrade domestic and decorative glass. Keeping in viewof its utilization in glass industries, proper attention isneeded with regard to its economic viability.

Acknowledgements

Authors are thankful to the Head, Department ofGeology, Banaras Hindu University for providingnecessary research facility to execute the work.

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2 Krishnan M S & Swaminath J, The great Vindhyan Basin ofNorthern India, Geol Soc India, 1(1959) 10-30.

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SRI V ASTA V A et al.: STUDIES OF GLASS SANDS 943

9 Singh R M & Singh G, Geochemical and sedimentological study of the Glass-sands near Shankargarh , district Allahabad, UP, Metals Min er Rev, 17(2) ( 1978) 23-32.

10 Shapiro L & Brounock W W, Rapid analysis of silicate rocks, Bull US CeDI Surv, l036C (I956) 19-56.

II Shapiro L & Brounock W W, Rapid analysis of silicate, carbonate and phosphate rocks , Bull US CeDI Surv, 1144A (1962) 56.

12 Folk R L & Ward W C, Brazos river bar, a study in the significance of grain size parameters, J Sed Pet, 27 (1957) 3-26.

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