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GENERAL INFORMATION ABOUT GOLD
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For the
past several years, the brilliant luster of Gold has
fascinated many. Since it was first found it has been a part
of our lives. To a lot of people Gold has not just been a
precious metal but an investment as well.
Since the stone age as
estimated 1,30,000 tones of gold has been produced, over half of which has
been mined since 1850.
It may sound surprising
but it is true that as many as 17 tones of ore is mined to extract a
single ounce (31.104gm) of gold.
Gold is available from
earth’s crust, in the seas, river and plants. In nature gold if found in
veins and secondary alluvial deposits as a free metal or in combined
state. Gold is also recovered as byproduct from Silver & Copper refining.
Placer mining or panning
and open pit mining is techniques commonly used to recover gold from
earth.
South Africa is world’s
single largest gold producer, followed by USA, Australia, Russia and
Canada and West Africa.
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Physical
and Chemical Properties of Noble Metals |
|
Metal
Name |
Chemical
Symbol |
Color |
Melting
Point |
Density |
|
Gold |
Au |
Yellow |
1064 C |
19.32 |
|
Silver |
Ag |
White |
962 C |
10.56 |
|
Platinum |
Pt |
White |
1773 C |
21.45 |
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Purity
Standards |
|
Percent
Gold |
European
System |
Karat
System |
|
100
% |
999 Fine |
24 K |
|
95.83% |
958 Fine |
23 K |
|
91.6 % |
916 Fine |
22 K |
|
87.6 % |
875 Fine |
21 K |
|
75.0 % |
750 Fine |
18 K |
|
58.3 % |
583 Fine |
14 K |
|
37.5 % |
375 Fine
|
9 K |
|
Percent : Parts of gold per 100 |
|
Fineness
: Parts of gold per 1000 |
|
Karat : Parts of gold per 24 |
NOTE :
Karat not to be confused
with CARAT, which is used to state the weight of a gemstone. However
in INDIA carat normally defines fineness of gold.
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Effect of
Acid on Metals:
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Gold: NO single acid can
dissolve or attack directly except in presence of oxidizing agent.
-
Gold will dissolve in Aquaregia
(1 part of Nitric Acid and 4 parts of Hydrochloric Acid)
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Gold will dissolve in Potassium
Cyanide in presence of oxidizing agent.
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An alloy of silver, copper or
zinc will attack gold.
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Silver will dissolve in Nitric
Acid.
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Platinum is almost resistance to
any acid.
Gold and Platinum have no weather
effect. In other words gold and platinum do not rust, tarnish or get
corroded. While in case of Silver it will be effected by atmospheric
pollution.
The typical composition of 23, 22, 21,
18, 14 and 9 carat yellow, red and white gold alloys.
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Typical Composition of Yellow Gold Alloys |
|
Grades
in Carat |
Metals,
Percent by Mass |
|
Au |
Ag |
Cu |
Zn |
|
23 |
96.00 |
4.00 |
- |
- |
|
96.00 |
2.00 |
2.00 |
- |
|
96.00 |
- |
4.00 |
- |
|
22 |
91.66 |
8.34 |
- |
- |
|
91.66 |
6.20 |
2.14 |
- |
|
91.66 |
4.10 |
4.24 |
- |
|
91.66 |
2.00 |
6.34 |
- |
|
91.66 |
- |
8.34 |
- |
|
21 |
87.50 |
12.50 |
- |
- |
|
87.50 |
10.00 |
2.50 |
- |
|
18 |
75.00 |
16.00 |
9.00 |
- |
|
75.00 |
12.50 |
12.50 |
- |
|
75.00 |
11.00 |
14.00 |
- |
|
75.00 |
9.50 |
15.50 |
- |
|
14 |
58.50 |
17.50 |
24.00 |
- |
|
58.50 |
15.00 |
26.50 |
- |
|
58.50 |
12.50 |
29.50 |
- |
|
9 |
37.50 |
17.50 |
42.00 |
3.00 |
|
37.50 |
11.00 |
51.50 |
- |
|
37.50 |
10.50 |
45.00 |
7.00 |
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Typical
Composition of Red Gold Alloys |
|
Grades in
Carat |
Metals,
Percent by Mass |
|
Au |
Ag |
Cu |
Ni |
Zn |
|
21 |
87.50 |
2.50 |
10.00 |
- |
- |
| |
87.50 |
- |
12.50 |
- |
- |
|
18 |
75.00 |
4.00 |
21.00 |
- |
- |
| |
75.00 |
2.50 |
22.00 |
- |
- |
| |
75.00 |
- |
25.00 |
- |
- |
|
14 |
58.50 |
7.50 |
34.00 |
- |
- |
| |
58.50 |
6.00 |
35.00 |
- |
- |
| |
58.50 |
5.20 |
36.30 |
- |
- |
|
9 |
37.50 |
7.50 |
55.00 |
- |
- |
| |
37.50 |
- |
61.00 |
- |
1.50 |
| |
37.50 |
5.00 |
57.50 |
- |
- |
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Typical
Composition of White Gold Alloys |
|
Grades in
Carat |
Metals,
Percent by Mass |
|
Au |
Ag |
Cu |
Ni |
Zn |
Pa |
|
18 |
75.00 |
15.00 |
- |
- |
- |
10.00 |
| |
75.00 |
8.00 |
- |
- |
- |
17.00 |
| |
75.00 |
- |
5.00 |
5.00 |
- |
15.00 |
| |
75.00 |
11.00 |
3.10 |
5.90 |
- |
5.00 |
| |
75.00 |
- |
5.50 |
14.50 |
5.00 |
- |
|
14 |
58.50 |
- |
18.00 |
17.50 |
6.00 |
- |
| |
58.50 |
- |
16.50 |
16.50 |
8.50 |
- |
| |
58.50 |
31.50 |
- |
10.00 |
- |
- |
| |
58.50 |
21.50 |
5.00 |
- |
- |
15.00 |
| |
58.50 |
18.00 |
6.50 |
2.00 |
1.00 |
14.00 |
|
9 |
37.50 |
- |
27.60 |
17.50 |
17.40 |
- |
| |
37.50 |
- |
40.00 |
10.70 |
11.80 |
- |
Some Useful Tips to
Remember:
1)
24
Karat - 100 %
- 999 Fine
22 Karat - 91.6 %
- 916 Fine
18 Karat - 75.0 %
- 750 Fine
14 Karat - 58.3 %
- 583 Fine
2) 01 Tola = 11.664 gm
10 Tola =
116.640 gm
01 Troy Ounce = 31.104 gm
01 Kilogram = 32.150 Tr.Oz
Last Update on
15/05/2006. |
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