Gold deposits of karnataka

1. SEMINAR ON

2. Contents:
Introduction
Origin
Gold deposits situated in karnataka
Formation of Kolar gold field
Kolar Gold deposites
Hutti Gold field
Mode of occurrence of Gold
Conclusions
References

3. INTRODUCTION
It also has complete resistance to the common
corrosive agents and there fore to oxidation and tarnishing. The Carat
is a useful indicator of the gold content of jewellery, 24 Carat being
pure gold.
Gold exhibits a combination of physical and chemical
properties which render it unique. It melts at about 1060 , has a
naturally lustrous colour. It is extremely malleable and ductile and is
efficient of electricity. Gold has a high specific gravity 19.6
Indian jewellery by for the largest demand is
usually 22 Carat, where the proportion of Silver is considerable.
Chemical symbol of gold is Au

4. ORIGIN
All primary Gold deposits are formed usually during the late
stages of the chilling of the magma ,which along fissures to the upper
layers of the earth`s crust from great depths. The Gold is transported
together with the magma from the depths of the earth in hot aqueous
solution and vapors. These solutions get solidified with the falling of
temperature, giving rise to ore bodies mostly in the form of veins in rocks.
These veins generally consist of Quartz with a small
admixture of other minerals. The particles of gold in the form of fine
grains, platelets and flaks and some times crystals wires, filaments
etc.
In the course of time these rocks and veins under the action
of geological agents, undergo mechanical disintegration and chemical
decomposition. The weathered products while being carried down to
the depositional site undergo the process give rise to placer Gold
deposits.
Economic gold minerals are
1) Native gold 2)Gold amalgam
3) Telluride(Calaverite, Sylvanite, Krennerite, Petzite )

5. MODE OF OCCURENCE
LODE GOLD
Gold occurs many geological settings. The following are the
important principal modes of occurrences observed in India.
STRATIFORM
GOLD IN GRANULITE BELT
DISSIMINATED
GOLD IN CONGLOMERATES
PLACER & ALLUVIAL GOLD
GOLD IN LATERITE SOILS

6. Gold deposits of Karnataka
There are two Gold fields situated in Karnataka. They are
1.KOLAR gold field 2.HUTTI gold field
In Kolar Gold field the Gold deposits are associated with
schistose rocks where aluminiumferous quartzite lodes occur along
closely placed mineralized zones.
In Hutti Gold field, the Gold deposits are occur along fractures
within chlorite schist's and greenstones in a highly regular manner.
These gold fields are within the Dharwar schist belts of Karnataka
KGF is about 30 kilometers from Kolar and 100 kilometers from
Bangalore.
Hutti is situated in Raichur District, Karnataka State, located at 80 km due
west of Raichur

7. Hutti gold fields

8. FORMATION OF GOLD IN KOLAR GOLD FIELD
The Kolar Greenstone or Schist Belt covers a 3 - 6km wide area
extending up to 80km in length. The rocks within the belt are comprised of
complexly folded and faulted mafic and felsic volcanic sequence generally of low
metamorphic grade.
The northern 40 km long portion of the belt has laterite cover
restricts exploration work
The three groups of the Kolar Gold Fields, being
Gold is preferentially concentrated in vein quartz, often associated
with sulphides. Most of these gold prospects represent typical Archean
hydrothermal lode gold mineralization.
South Kolar
 East Kolar
North Kolar

10.  North Kolar covers the northerly extension of the Kolar
Greenstone Belt and includes major synformal fold.
 Lode gold mineralisation is hosted by shear zones, sheared
granite and quartz viens.
NORTH KOLAR
Quartz bodies of different types, both barren and mineralised
and several generations occur in the ferruginous and
carbonaceous Phyllites and within linear bodies of metagabbro.

11. SOUTH KOLAR
 mineralisation occurs near to the contact of the mafic
amphibolitic metabasalt with felsic volcanic and metasediments
of the Champion Gneiss.
 Gold is concentrated in vein quartz and also associated
with sulphides.
 The zone having highly sulphidic rocks and at one of the
prospects and quartz viens on the other end.

12. EAST KOLAR
 This horizon is a heterogeneous assemblage of volcano-
sedimentary rocks.
 The volcanics are represented by rhyolite and acidic tuffs of
dacitic composition. All these are deformed and metamorphosed
to lower amphibolite facies.
 Gold mineralisation in the Surapalle area occurs in highly
tectonised shear zones which transect the foliation at a very low
angle

15. Kolar gold field have four productive mines
oNandydurg mine oChampian reef
oMysore mine oOoregum
The champian reef mine is one of the deepest mine in
the word.
The average content of champian reef was 15grams/tonn
There were about 15 parallel lodes in the kolar gold field, in
them 6 were gold-quartz lodes,9 were gold-quartz-sulphide
lodes
About 84 tones of gold have been produced since the mines
were nationalized

16. Champion lode of Kolar gold field:
The gold -quartz lode is localized along a shear zone traversing
the mafic rocks of komatitic and tholeitic character
This lode have been mined over a strike lenth of more than
8 km and to depth of 3400 mts.
Lode are mainly made up of quartz and calcite .Other
minerals include sheelite, biotite, muscovite, and
tourmaline. Sulphides are pyrite, arsenopyrite, pyrhotite,
chalcopyrite and galena. High values of Cr and Ni are also
noticed

17. The wall rock reaction have taken place along the
structural features.
REE geochemistry of quartz-carbonate lodes indicate light
REE compared sulphide lodes. Mobilization of gold took place
around 2600my
The important wall rock alteration which accompany
the mineralization are sericitization, chloritization,
biotization, carbonization and greisenization.
(CONT..)

18. Stratiform Sulphide type:
The Oriental lode of KFG is a stratiform sulphide type lode
lying about 400 to 500 mts to the west of champion reef
lode in north Kolar.
It is strongly a pyritic lode. Width of this lode is ranges
from 1.5mts-4.5mts
This lode is localized between volcanic flows and it is
made up of alternating bands of sulphide and amphibole-
quartzite encountered in archian schist belts
Dominating sulphide minerals are pyrhotite with
arsenopyrite and minor pyrite chalcopyrite and sphalerite.

19. HUTTI GOLD FIELD
There are number of gold bearing quartz veins extensively
mined to shallow depths
There is a number of old prospects include
HUTTI, MASKI, BUDINI, TOPDUR, CHIKHARUR, TOPPALDODDI,
WONDALLI, KADONI, UDBAL, MUKANGAVI
The country rocks are greenstones, cherts, chlorite
schist intruded by granite, quartz, porphyry gabro and
dolerite dykes.
There 6 auriferous qurtz reefs
strike
village
Zone-1
Middle reef
oakely`s reef
Main reef

20. In the Main reef Quartz veins occupy fissures in
surrounding rocks.
The quartz occurs in the form of lenses, often
less than 100 ft in depth.
The pyrites are abundantly developed in grains and
crystals throughout the lodes. The gold is free and it
has been deposited independently of pyrite
Samples from the southern extension of Main reef gave
22gm/ton over 0.35mts, 20gm/ton over 0.45m, 10gm/ton
over 0.60m

21. Oakery`s reef in the hutti gold field have been provided to
be auriferous over a strike length of 213mts with 1.25gm/ton
to 9.98gm/ton
Up to 1990 about 33 tonnes of gold have been recovered
from 5 million tonnes of ore at a recovery grade of
6.52gm/ton.
 The company formed in1947 to mine the Hutti gold field, as
the Hyderabad gold mine company ltd, with the Hyderabad
state gov.Then transformed to Karnataka state and became the
Hutti gold mines company ltd

22. CONCLUSIONS:
 Gold has been prised high and considered as king of
the metals.
Kolar and hutti gold fields are important gold producing
centers in karnataka
Champion reef is the richest gold bearing quartz-lode
in so far encountered in india.
The champian reef mine is one of the deepest
mine in the word.
Gold deposits generally occurs with quartzite and sulphide
lodes within these two gold fields
Main reef is the important gold producing reef among
the Hutti gold field

23. B.P.Radhakrishna (1990) GOLD –the Indian scene ,
Published by GSI,p:143
K.V.G.K.Gokhale&T.C.Rao Ore deposites of India
Thomson ltd.1973, p:101
REFERENCES:
http://www.search.ask.com/web?q=kolar+gold+field
http://en.wikipedia.org/wiki/Hatti_Gold_Mines