2. INTRODUCTION
Gold is a transitional metal. In its purest form have reddish
yellow color, soft, malleable, and ductile metal.
Atomic number : 79
Atomic mass : 196.9 u
Density : 19.32 g/cm3
Melting point : 1,064 °C
Boiling point : 2,700 °C
Founded in different form associated with different rock type
in different tectonic setting.
Discovered from earlier time and used for multi purposes.
3. Types of gold deposits and it’s mine
TYPE OF DEPOSITS MINE
Placer ores Placer mining
Oxidized ores Open pit
Primary ores Underground mining
4. Formation of gold
• The saying among prospectors that "gold is where you find it"
suggests its occurrence is unpredictable, but there is some certain
geological environments for the formation.
• Because gold is very stable over a range of conditions, it is
widespread in the earth’s crust.
• Gold dissolved in warm to hot salty water, the fluids are
generated in huge volumes deep in the Earth’s crust as water-
bearing minerals dehydrate during metamorphism.
• Any gold present in the rocks being heated and squeezed is
sweated out and goes into solution as complex ions.
5. • In this form, dissolved gold, along with other elements such
as silicon, iron and sulphur, migrates wherever fractures in
the rocks allow the fluids to pass.
• The direction is generally upwards, to cooler regions at
lower pressures nearer the Earth’s surface.
• Gold eventually becomes insoluble and begins to crystallize,
most often enveloped by quartz.
• The association of gold and quartz vein forms one of the
most common types of "primary gold deposits".
8. • In India, gold mineralization of economic importance is mainly
restricted to Archean greenstone terranes of the Dharwar Craton
(DC).
• The eastern block of the DC has a high favorability for hosting
major gold deposits such as Kolar, Hutti, and Ramagiri,
whereas the western block hosts only a few smaller deposits
such as Gadag, Kempinkote and Ajjahanahalli.
• Gold also discovered by GSI in the Singbhum Craton, Aravalli
Craton, Bastar Craton and Southern Granulite Terrain (SGT).
9. • India currently holds about 558 tones of gold, representing
6.6% of its reserves, (World Gold Council, October 2016).
• Kolar Gold Field, Hutti Gold Field and Ramgiri Gold Field
are the most important Gold fields.
• India is the second-largest consumer of gold after China.
16. The prospects in SGT have been considered as the promising
areas for detailed exploration of gold.
The gold prospects in SGT can be broadly grouped into three
provinces
• Wynad-Nilgiri
• Malappuram
• Attappadi
All these prospects are located within the Cauvery Suture
Zone (CSZ).
Gold mineralization is associated with primary quartz
veins, placer and laterite.
19. Wynad-Nilgiri province
• Is located south of the Moyar Shear Zone (MSZ).
• Consists of :
o Migmatitised hornblende gneiss,
o Amphibolite, biotite gneiss,
o Garnet–biotite–sillimanite gneiss,
o Pyroxene granulite,
o Banded magnetite quartzite
• The auriferous quartz veins crop out as discordance with biotite
and hornblende-bearing gneiss and amphibolites in Maruda.
• Trending NE–SW, moderate to steep dip with an average width
of 0.5 m.
20. • Exploration and mining of gold in Wynad - Nilgiri
province was on progress during British rule in India as
reported from the note of King.
• The mineralized veins in these prospects have assay value
varying from 1 to 39 g/t of Au.
• Auriferous veins in this province are confined to 25 km
long and 10 km wide, NE–SW trending regional shear
zone.
24. Karnataka
• It is the largest producer of gold in India.
• Gold mines are located in Kolar, Dharwad and Hutti Gold
Field.
• Kolar Gold Fields is second deepest mines in the world
after Mponeng is south Africa (3.9 km).
25. Kolar Schist Belt
• Kolar schist belt is the richest ‘gold belt’ of India and ranks
among some of the foremost similar greenstone belts of the
world.
• During the last decade, the average grade of ore hovered
between 3 and 5 g/t
• The rocks of the schist belt show three phases of folding
and low pressure amphibolite facies of metamorphism,
B.I.F, metamorphosed basic volcanic rocks Recent
radiometric dating indicated around 2700 m.y.
26. • Broadly two types of gold mineralization i.e. gold- quartz
(free-milling type) and gold-sulphide-quartz lode
(refractory type) have been identified from this belt.
• Control of mineralization is structural control (shear zones)
• Kolar Gold Fields still has reserves that could yield 10
tonnes of gold per year for 15 years.
29. Hutti Gold Mines Ltd.
• One of the major gold producer mine in India, it is consist of
many field among them Hira-Buddini and Uti are the most
productive
• The host rocks are amphipolite and gneiss with quartz vein and
quartz lode sulphide.
• The Hutti mines has proven reserve of 52.55 tones and inferred
resource of over 75 tones.
• In 2010-11 the mine production was 2.22 tones.
• The mines has a production schedule according to which it aims
to reach a production of 2.9 tones during the 2011-2016 period.
33. Rajasthan
• Base metal mineralization in Rajasthan is most extensive
as indicated by clusters of ancient workings and the
present mining activity.
• The occurrence of gold, has been postulated in the
Paleoproterozoic belt extending from Nathdwara in the North
to Jhabua in Madhya Pradesh in the South, related to
greenstone belts.
• But little work has been done on the gold mineralization
hosted by the Paleoproterozoic sequence in Rajasthan.
• The Geological Survey of India has reported the occurrence of
copper and gold (0.1-2.6 g/t) in Ladera-Sakhun area.
35. Gold ore processing
The process can be done in four steps
Ore
Preparation
• Particle size
adjustment to
next processes
• Physical
concentration
and oxidation
pretreatment
Gold
Extraction
• Extraction of
gold from ore
into solution
and/or
concentrate
Gold
Purification
• Purification
of gold
bearing
solution
Gold
Production
• Recovery of
gold from
solution
37. Gold Demand and Use
• The largest source of demand is the jewelry industry Gold’s
workability, unique beauty, and universal appeal make this rare
precious metal the favorite of jewelers all over the world.
• Besides jewelry, gold has many applications in a variety of industries
including aerospace, medicine, dentistry, and electronics for the
manufacture of computers, telephones, televisions...
• The third source of gold demand is governments and central banks
that buy gold to increase their official reserves.
• Private investors there are private investors. Depending upon market
circumstances, the investment component of demand can vary
substantially from year to year.
38.
39. Gold and environmental impact
• Gold mining is one of the most destructive industries in the
world.
• It can displace communities and destroy pristine
environments, hurt workers.
• Contaminate drinking water.
• It pollutes water and land with mercury and cyanide
• Endangering the health of people and ecosystems.
• Producing gold for one wedding ring alone generates 20
tons of waste.
40.
41. CONCLUSION
• Gold one of the most precious base metal that has been
discovered and treated since long time back
• Has different occurrence and different uses
• Usually primary gold associated with quartz vein
• Gold in India associated with greenstone belt
• SGT considered as the most promising gold field
• Kolar, Hutti are the most productive gold field.
• The precious metal has also negative impact on the
environment
42. REFERENCES
• Geological survey of India (1994), Detailed information on gold ores in India, Geological
survey of India, 89 P.
• Geological Survey of India (nov 2011), Base document on Precious Metals & Minerals [Gold,
PGE, Diamond and Precious stones] CGPB Committee II, Geological Survey of India , 183 P.
• Ajit Kumar Sahoo, Rajagopa lKrishnamurthi, RavikantVadlamani,Kamal Lochan Pruseth
,Manju Narayanan,SajuVarghese and T. Pradeepkumar, Genetic aspects of gold
mineralization in the Southern Granulite Terrain, India. Ore Geology Reviews, 72 1243–
1262 (2016).
• N. N. Singh, A note on gold in southern Rajasthan-A conceptual model. International Journal
of Advancements in Research & Technology. Volume 3, Issue 1, 2278-7763 (2014).
• http://www.sbs.com.au/gold/story.php?storyid=128
• http://www.usfunds.com/slideshows/the-many-uses-of-gold/#.WHkElNJ97IV
• http://www.profitconfidential.com/gold/top-10-countries-highest-gold-reserves/
• http://investopiagroup.com/gold-demand-and-use/
• http://nodirtygold.earthworksaction.org/impacts#.WIrGPNJ97IU
