Technical

MEASURE OF WEIGHT   

The traditional unit of weight for gold is the troy ounce from the Anglo-Saxon system of weights and measures. Troy weight originates from the troy system of mass. This dates back to before the time of William the Conqueror. The name troy comes from the city of Troyesin France, which was an important trading city in the Middle Ages. Although the metric system is used increasingly in mining and the gold business, the troy ounce remains the basic unit in which the price of 99.5% gold is quoted. The following conversion data will provide some familiar measure.

1 troy ounce

=

31.1034807 grams

1 troy ounce

=

480 grains

1 troy ounce

=

20 pennyweights

3.75 troy ounce

=

10 tolas (Indian sub-continent)

6.02 troy ounce

=

5 taels (Chinese)

32.15 troy ounce

=

1 kilogram

32150 troy ounce

=

1 metric ton (1,000 kilograms)

1 Grain

=

0,06479891 grams

1 Pound

=

12 ounces

1 pennyweight

=

1.5551738 grams

1 pennyweight

=

24 grains

Archives

KARATS AND FINENESS

One often hears when gold jewelry is described that it is expressed in karats. Karats are used to express the fineness of gold. The scale of fineness is a measure out of 24. 24 Karats implies at least 99.5% is gold. This high percentage of gold is often also described as fine gold. 12 Karats will mean 50% gold. The following table will clarify karats as an expression of fineness.

KARATS

FINENESS

24.0 kt.

999.00

22.0 kt.

916.60

21.5 kt.

895.80

21.0 kt.

875.00

18.0 kt.

750.00

14.0 kt.

583.30

12.0 kt.

500.00

10.0 kt.

416.60

9.0 kt.

375.00

8.0 kt.

333.00

Krugers

Alloys Explained Us

Altermore 1

An alloy is a mixture of two or more metals for a specific purpose. In the context of gold, the one addition to form an alloy will be gold. Other metals added to gold are copper, iron, aluminum, silver, platinum, palladium, nickel, zinc and titanium. The purpose of these alloys is to add color and strength. Gold in its purist form is very soft and can easily be deformed. For many applications gold needs to be alloyed for strength. This is true for the minting of coinage and jewelry.

It is with gold alloys that the term karat comes in to play. The Kruger Rand for an example is 22 karat which means that it is 91.66% fine gold. The other metal used in the alloy combination is copper. The copper is used as a hardening agent for durability in resistance to scratches and other wear on the coin. In respect to gold jewelry it is often expressed in 8, 12, 16 and 18-karat fineness. The color and hardness of the jewelry will depend upon the other metal/metals used.

Often the term white gold is confused with platinum. White gold is exactly what the description says; “white gold”. White gold is a gold alloy where the other metal/metals used are zinc, nickel, platinum or palladium in part. The color of the alloy will appear white but in fineness it may be 12 karat gold. Adding copper yields a redder color, iron green, silver green, aluminum purple, platinum metals white, and natural bismuth together with silver produces black gold.

GOLD: VERY TECHNICAL

The following information is for those who seek “all knowledge”! For most of us this information is totally useless but in the spirit of completeness we go down to atom level, literally. Gold is a chemical element in the periodic table that has the symbol of Au (Latin for Aurum) Gold is a soft, shiny, yellow, dense, malleable, ductile (trivalent and univalent) transition metal. Gold does not react with most metals but is attacked by chlorine, fluorine and aqua regia (A yellow fuming corrosive mixture of nitric and hydrochloric acid that dissolves metals including gold). The metal occurs as nuggets or grains in rocks and in alluvial deposits. The ISO currency code for gold is XAU. The following information is the very technical regarding gold:

Name

=

Gold

Gold Symbol

=

Au

Atomic Number

=

79

Group

=

11

Period

=

6

Block

=

d

Appearance

=

Metallic Yellow

Atomic Mass

=

196.966569(4) g/mol

Electron Configuration

=

[Xe]4f 14  5d 10  6s 1

Electrons per shell

=

2, 8, 18, 32, 18, 1

Phase

=

Solid

Density (near r.t.)

=

19.3 g/cm? Elucidation: Compare the above with Aluminium: 2.7 g/cm? Iron:7.87 g/cm?

Liquid density at m.p
(melting point)

=

17.31 g/cm?

Melting point

=

1337.33K, 1064.18°C, 1947.52°F

Boiling point

=

3129K, 2856°C, 5173°F

Heat of fusion

=

12.55 kJ/mol

Heat capacity

=

(25 °C) 25.418 J/(mol·K)

Crystal structure

=

cubic face centered

Oxidation states

=

3,1 (amphoteric oxide)

Electron negativity

=

2.54 (Pauling scale)

Ionisation energies

=

1st: 890.1 kJ/mol

Atomic radius

=

0.1442nm

Electrical resistivity

=

0.022 micro-ohm m at 20 °C.

Thermal conductivity

=

310 W m -1  K -1  at 20 °C.

Hardness (Hv)

=

25

Tensile stress (MPa)

=

124

Number of naturally occurring isotopes

=

1

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