F i g

a 30V,E<e(A

D I S T R I B U T I O NOF

GOLD VALUES

at«•

OVGold Values in Dwts. per Ton

r ROGRESSIVE D ISTR IB U TIO NOF

GOLD VALUES

o> AO * / • -

20 V . -

2822Gold Values in Dwts. per To

*

S. 3 0 ° / . -D I S T R I B U T I O N

OFGOLD VALUES

Gold Values in Dwts. per Ton

8 0 ° / . -

RROGRESSIVE D IS TR IB U T IO NOF

GOLD VALUES

16 18 Dwts. per Ton

UGold Values

■ 1 III—

GRAPH ILLUSTRATING THE R EL A TIO N S H IP OF GOLD SILVER AND IMPURIT IES IN BARS OF GOLD BULLION

Fig.U.PATin O F O R E M I L L E D .

O X I D ISED S U L P H I D E 3 7 : 1

RATIO OF ORE MILLED OXIDISED SULPHIDE

2 9 : 1

1 0 0 0

AGOLD

i \

< 5 0 0

Hi 4 00

1

IMPURITIES

P U 4' H i .

b a r s of g o l d b u l l i o n

PART

S PE

R TH

OU

SAN

D

P i r a t i n g t h e r e l a t i o n s h i p o f g o l d s i l v e r a n d i m p u r i t i e s i n b a r s o f g o l d b u l l i o n .GRAPH I

RATIO OF ORE MILLEDRATIO OF ORE MILLEDR ATIO OF ORE MILLED OXIDISED SULPHIDE

OXIDISED SULPHIDE 0 6 1

OXID ISED t u L P H I DE 0 3 1

GOLD

S ! i wER

IMPURITIESI I I

P 3 2 7 C P 3 3 7 C P 3 4 7 CP317CP 3 0 7 CP?97CR267C P277C P 2 8 X

BARS CF COLD BULLIONP2S7CP 7L 7CP 2 37CP2 2 7CP217C

A.

1 5,0 0 0

1 0,0 0 0coinoz3

o

o. joO

5,0 0 0

K E YOu n c e s of G o l d r e c o v e r e d f r o m O reM IL L E D .

vrm O u n c e s o f G o l d r e c o v e r e d f r om t h e R e ' . e a t m e n t o f S a n d s a n d S l i m e s .

rrmrmo<N

«n r> -n* m CO Ot O <N <*>•i, f" • <r o »- cn m ^ u> «> r** ® o>m ob cn om m m Mo» o» w ^

QUJ

<Z)Zo

3 0,0 0 0

2 0,0 0 0 - —

1 0,0 0 0

I n f l i

to r* oo cn o «- cn m •«» un <n co cn o •- <nO O O O v— ▼— v— v— C4 CN< 7 > c n c n c T > < n < n c n < n c n a > < n e n t n c n c n o t < T i O ' <T‘ CT' ^ _ t n _ ^ . ^ ^ . „ ^ . ^ .

Fig.16.D.

I 4 0,0 0 0

3 0,0 0 0 -----

toLUU3o

2 0,11)0 —

ooCD

1 0,0 0 0

I I I I I I I I N IW) to to to

t n c n t n t n c n t n m c n c n c n c n c r

to r- < o o » w o * - f s « r n ' *i / ) t O i n m i / > t o t o t o t o t o

OCa.

zD

UJ wz z

aUJ

V u UJ uj

V o u uUJ UJ3 3 0 0 0 0 0 0 0 0

A. H i s t o g r a m r e p r e s e n t i n g Ounces o f G o l d r e c o v e r e d f o r t h e

P e r i o d 1 9 0 7 to 1 9 4 0 .

B . H i s t o g r a m r e p r e s e n t i n g To n s M i l l e d f o r t h e P e r i o d 1 9 0 7

to 1 9 4 0 .

C . H i s t o g r a m r e p r e s e n t i n g O u n c e s o f G o l d r e c o v e r e d f o r t h e

P e r i o d 1 9 5 6 to 19 6 6 .

D . H i s t o g r a m r e p r e s e n t i n g To n s M i l l e d r oR t h e P e r i o d 1 9 5 6

to 1 9 6 6 .

aUJ

inzo

2 0 0,0 0 0

1 5 0,0 0 0

1 0 0,0 0 0 -

5 0,0 0 0

r ! i m M i i i ito t~ <o <n cn o «—tn m a> u> m to toa* cn cn w o' tn cn

«n «wi «• tn u>«o «o to to tocn o> o> Ot o'

UJ UJ UJ o o o o o u u u Z Ul UJ U* UJ Ui UJ UJ UJ3 0 0 0 0 0 0 ° °— z z

0C 3 3(L -> ■x<

The author wishes to express his appreciationto the management of Rio Tinto (Rhodesia) Ltd. forpermission to publish this thesis.

For their close co-operation and help the authorwishes to thank the following members and former members of the Rio Tinto Group, Dr. J. V.'. H . _Sharpe, Dr. P. r • _ C o l l e n d e r , Messrs. W. V. Rickards, G. Logan, T. h._Dane, p. B. Batty, G. C. Bluett, R. Gersteling, T. Blyth,F. van Tender, P. Connear, P. Luxat and J . Grabe.

The a u t h o r g r a t e f u l l y a c k n o w l e d g e s t h e h e l p

r e n d e r e d h i m by h i s s u p e r v i s o r P r o f e s s o r L. M e n d e l s s o h n ,

as w e l l as m e m b e r s o f s t a f f i n the d e p a r t m e n t o f g e o l o g y

at t h e U n i v e r s i t y of t h e W i t w a t e r a r a n d .

Thanks are due to Kiss M. V/aghom, Miss L. Delland Mrs. K. I’ahrbach for the typing of this thesis.

To my wife, Diana, and my parents Dr. ana Mrs.r . IT. Johnson, my sincerest gratitude ior -heirencouraging and continuous support.

79

XII.

AiTHAEUL SER, C . ROERING-, C. , VILJOEN, M.J., VILJOEM, R. P.

BATEMAN, A. M.

De SITTER, L.

EMviONS, W. H.

REFERENCES

(196?) The Barberton Mountain Land: A Model of theElements and Evolution of an Archean Fold Belt.Inform. Giro. No. 38..

Econ, Greol. Res. Unit. Univ.W i tv/at ers ran d, Jo harm' 'burg.

34 p.9

(1955) Economic Mineral Depr' iita f 2nd Ed. Chapman and hall Ltd., London, p. 94 - -0 6 ,

p. 303 - 314.

(1956) Structural Geology, Tst -d. McGraw-Hali Book -o., rnc., New York, p. 87 - 89, P*251 - 260, p. 292 - 299,p. 442 - 449•

(1933) On the Mechanism of the Deposition of certain Metalliferous Lode oysi /ms associated with Granitic Batholithe. Lindgren Volume Amer. Inst. - ining <-nd ^Metallurgical Engineers,New York, p. 327 - 349

80

GOVETT, G. J.

HARKER, A.

HOLt:LES, A.

KING, L. C.

LABERGE, G. L.

(1966) Origin of Banded IronFormations, Geol. Soc. America, Vol. 77, No. 11, p. 1191 - 1206.

(1956) Metamorphiam. Methuen and Co. Ltd., London, p. 177 - 189, p . -?03 - 214, p. 277 - 287, p. 544 - 352.

(1965) Principles of Physical Geology. New and Fully Revised Edition. Thomas Nelson and Son, Ltd.,London, p. 202 - 206, p. 236 - 239, P. 279 - 284 p. 1169 - 1171, P. 1184 - 1186.

(1962) F _ogy of the Earth.01 r and Boyd, Edinburghand London, p. 254 - P* 276.

(1966) Altered Pyroclastic RocksIron-Formation in the

Hammersley Range, "'estern Australia. Econ. Geol.Bull. Soc. Econ. Geologists,

Vol. 61, p. 147 - 161*

81

LABERGE, G. L.

LEPP. H., GOTiDWICH, S. S.

LIGHTPOOT, 5.

M o GREGOR, H. A.

PETTIJOHN, P. J.

PPLUG, H. D.

(1966) Altered PyroclasticRocks in South African Iron-Pormation. Econ.Geol. Bull. Soc. Econ. Geologists, vol. 61, p. 572 - 581.

(1964) Origin of Precambrian Iren Formations. Econ. Geol. Bull. Soc, Econ. Geologists, Vol. 59, p. 1025 - 1060.

(1954) The Larger Gold Mines of Southern Rhodesia. Geol.

/

Sure S e Rhode Bulle - 0 e 26,

p. 73 - 80.

(1932) The Geology of the Country around Que 1'ue, Gvvelo District, Geol. Sur,S. Rhod. Bull. Ho. 20,P. 15 - 46 e

(1957) Sedimentary Rocks, 2nd Id. Harper and Brothers, New York, p. 458 - 464.

(1966) Structured Organic domains from the Fig Tree Seraes of the Barberton fountain ̂ Land. Inform, "ire. No.2d, Econ. Geol. Res. Unit,

RAIVlBERG , H.

SWIFT, W.H.

WILES, J.W.

WILES, J.W

ZEALL21, A. ELIGIi'J'POOT , B

Univ. Witwatersrand, Johannesburg. 31 p.

(1955) Natural and Experimental Boudinage and Pinch-and- Swell Structures. Jour.Geol. Vol. 63, p. 5 1-526.

,1961) An Outline of the Geolog"of Southern Rhodesia. Geol. Sur. S. Rhod. Bull. Jo. 50, p. 4 - 17.

(1957) The Geology of the Eastern Portion of the Hartley Gold-Belt. Geol. Sur. S.Rhod. Bull. No. 44, Part I, 103 p.

(1957) Gold Deposits and Pines.Geol. Sur. 5, Rhod. ull.No. 44, part II, p. 1 - 4,p. 119 - 122.

(1918) The Geology of the Country around Gatooma. Geol. ■ -* - • S. Rhod. Bull. No. 5, 68 p.

" • *• •'-•T'.- 6*0 ' ! • : ••

PLATE I

v<! - * ri . v * • 1

‘ • //" y‘.

V

>4 ' Vg

y ' W T ' A V' ■ i

'

Pig. 1. An aerial photograph of the iickstone Mine. Scale:- 1:25,000. Photographed in June, 1966.

\

i* ——T-

PLATE II

Fig. 2. Picks tone Mine plant and the slimes, andflotation tailings dams. Mcmbi River trans­gressing lov/er group of Shamvaian grits, the Pickstone oblique-dip fault, and low, even country of undifferentiated sediments of the upper group of the Shamvaian System.

Fig. 3. Burnett Shaft headgear with rough ore-bin situated behind the compressor water- cooling tank.

PLATE III

4. Low, mature, terrain of the Rhodesde 5 Lranite uatholith, and peripheral gold-belt rooks of higher relief. Plic to graph taken from the top. of Duchess Hill looking towards the southwest.

5. Weathered slabs of highly sheared and foliated felsJ te and quartz-porphyry. These rocks fon-i the south wall-rock of the Pickstone banded , iaspilite host rock.

, -r

PLATE IV

Allow

Fig# 6. Steeply-dipping contact between sheared pillow lava of the Bulawayan System and grits of the Shamvaian System, exposed in the dry bed of tneMombi River.

h . :> .

---

w m

Pig. 7 High ridge of Shamvaian gri a 3.0 Qparallel ridge of Peerless l i i i e s t o ,-^ out­cropping behind the Pickst. :lr 16

N

v f'1'

* 1

r

PLATE V

Pig. 0. Old surface workings of the Picks tone banded jaspilite host rock on Concession Hill.

Pig. 9. An ore spec'«en showing two parallel, milhy — arts fracture

I

PLATE VII

Pig. 12

fWPyx<^>

it

Granite etook. Irregular grains of epidote surrounded by green biotite flakes.

X 30Open NiceIs

Pig. 13 ==EEEEEr= s r s r *

X 7 0x - Njcols

PLATE VIII

L4. Speckled chlorite schist, Bulawayan System. Complete sericitization of felspars giving sericitic and chlorite lenticules•

X 70

1 F'

K W * ' r-r ,

* * . . . -f'

15. Felaite extrusive, Bulawayan System. ubirefringent cryptocrystalline pyrophylliteformed by recrystallization of originalfelsite constituents

X 300 X - Nicols

PIATE IX

Q u a r tz -P o rp h y ry , Bulawayan System, Sheared and c ra cke d q u a r tz p h e n o c rys t in a c ry p to c r y s t a l l i n e groundmass o f p y r o p h y l l i t e and

q u a r tz .X 30X - N ic o ls

F ig . lb

F ig . 17

XX - Nicols

PLATE X

Banded jaspilite host rock, Bulawayan Systen. Euhcdral and subhedral cry-, taie o f a rs e n c p y r ite and pyrite, showing preferential replacement the chemically favourable siderite bands.

X 30X - Nicole

¥

PLATE XI

Pig. 20. Banded jaspiiite host rock, Bulawayan System.Sulphide crystals surrounded by impressive looking "flame quartz", derived from therecrystallization of the cryptocrystalline quartz.

X 70X - Nicola

Banded jaepili.e Met rock, Bula.apm, oystc Sulphide crystals replacing * er adjacent quartz ^

Pig. 21.

X - N10

PLATE XII

Pig, 22. Pillow lava, Bulawayan System. liinute latheof soda-rich plagioclase 'a a groundmass of chlorite. Small vein filled by highly birefringent carbonate.

X toX - Nicols

Pig. 23 Pillow lava, Bulaw van System. Twinning In I n t o laths of plagiodsae in a groundmass

PLATE XIII

Pig. 24, Pillow lava, Bulawayan System. Microtextureresembling an amygdale and consisting of brown cryptocrystalline unidentifiable material.

X 70X - Nicols

Pig. 25.

*1

PLATE XIV

Fig. 26. Quartz grit, Shamvaian System. Large subangularquartz grains cemented by sma.].! interlocking quartz grains. Birefringent sericite is presentinterstitially.

X 30X - N ic o ls

27. D o le r i t e s i l l , tra n s g re s s e s the

Si*

PLATE XV

shownn e t y p y r i t e

P ig . 29 . S u b h e d ra l c r y s ta ls o f a rs e n o p y r ite (e tched )e n c lo s e d by m assive p i t t e d p y r i t e .x 300

p: .t3 xvi

Pig. 30

Pig.

Pvrite cut enclosed in massive arsenopyiiteX 75

* **

PLATE XVII

p-j r, 32. Pine-grained subhedral crystals of arsenopyriteand pyrite along the boundary of late milky vein quartz fracture-filling (dark patch) with larger crystals developed further from the vein-quartz.

X 150

Chaleopyrite (light grey) fonned between inter- locking grains of arsenopyn-e.

X 6UU

PLATE X V I I I

Gold (scratched) enclosed in ars~nopyrite. Chalcopyrite (light grey) filling .ractui-es inthe arsenopyrite.

X 300

/ T

PLATE XIX

Gold (scratched) moulded onto subhcdral arseno- pyrite crystal and massive pitted pyri te.

X 300

- 1

laler'.te (grey) filling fractures in a a rs e n o p y r ite and as irregular

PLATE XX

Pig. 38. Pseudomorph of crystal of arsenopyrite alteredto hematite and hydrated iron oxide.

\

Author Johnson RSName of thesis The Geology of the Pickstone Gold Mine Hartley District Rhodesia 1967

PUBLISHER:University of the Witwatersrand, Johannesburg ©2013

LEGAL NOTICES:Copyright Notice: All materials on the Un i ve r s i t y of t he W i t w a t e r s r an d , Johannesbu r g L i b r a r y website are protected by South African copyright law and may not be distributed, transmitted, displayed, or otherwise published in any format, without the prior written permission of the copyright owner.

Disclaimer and Terms of Use: Provided that you maintain all copyright and other notices contained therein, you may download material (one machine readable copy and one print copy per page) for your personal and/or educational non-commercial use only.

The University o f the W itwatersrand, Johannesburg, is not responsible for any errors or omissions and excludes any and all liability for any errors in or omissions from the information on the Library website.

Author Johnson R S Name of thesis The Geology of the Pickstone Gold Mine Hartley District Rhodesia 1967

PUBLISHER: University of the Witwatersrand, Johannesburg

©2013

LEGAL NOTICES:

Copyright Notice: All materials on the Un i ve r s i t y o f the Wi twa te r s rand , Johannesbu rg L ib ra ry website are protected by South African copyright law and may not be distributed, transmitted, displayed, or otherwise published in any format, without the prior written permission of the copyright owner.

Disclaimer and Terms of Use: Provided that you maintain all copyright and other notices contained therein, you may download material (one machine readable copy and one print copy per page) for your personal and/or educational non-commercial use only.

The University of the Witwatersrand, Johannesburg, is not responsible for any errors or omissions and excludes any and all liability for any errors in or omissions from the information on the Library website.