What is Gold and why is its chemical symbol Au?
Gold is a rare metallic element with a melting point of 1064 degrees centigrade and a boiling point of 2808 degrees centigrade. Its chemical symbol, Au, is short for the Latin word for gold, 'Aurum', which literally means 'Glowing Dawn'. It has several properties that have made it very useful to mankind over the years, notably its excellent conductive properties and its inability to react with water or oxygen.
Why is gold measured in carats?
This stems back to ancient times in the Mediterranean /Middle East, when a carat became used as a measure of the purity of gold alloys (see next Question 5). The purity of gold is now measured also in terms of fineness, i.e parts per thousand. Thus 22 carat is 22/24th of 1000 parts = 916 fineness.
What is a Carat?
A Carat (Karat in USA & Germany) was originally a unit of mass (weight) based on the Carob seed or bean used by ancient merchants in the Middle East. The Carob seed is from the Carob or locust bean tree. The carat is still used as such for the weight of gem stones (1 carat is about 200 mg). For gold, it has come to be used for measuring the purity of gold where pure gold is defined as 24 carats. How and when this change occurred is not clear. It does involve the Romans who also used the name Siliqua Graeca (Keration in Greek, Qirat in Arabic, now Carat in modern times) for the bean of the Carob tree. The Romans also used the name Siliqua for a small silver coin which was one-twentyfourth of the golden solidus of Constantine. This latter had a mass of about 4.54 grams, so the Siliqua was approximately equivalent in value to the mass of 1 Keration or Siliqua Graeca of gold, i.e the value of 1/24th of a Solidus is about 1 Keration of gold, i.e 1 carat.
How does a gold mine work?
The gold-containing ore has to be dug from the surface or blasted from the rock face underground. This is then hauled to the surface and milled to release the gold. The gold is then separated from the rock (gangue) by techniques such as flotation, smelted to a gold-rich Dore and cast into bars. These are then refined to gold bars by the Miller chlorination process to a purity of 99.5%. If higher purity is needed or platinum group metal contaminants are present, this gold is further refined by the Who l will electrolytic process to 99.9% purity. Mine tailings containing low amounts of gold may be treated with cyanide to dissolve the gold and this is then extracted by the carbon in pulp technique before smelting and refining.
Alchemy: Can base metals be turned into gold?
All metal atoms are made of the same building blocks of protons, neutrons and electrons, but in different quantities, so in theory it could be possible to change base metals into gold or any other metal of value to mankind. In practice, it is achieved only in nuclear reactions, where heavy radioactive metals decay into other lighter elements, including some isotopes of gold. However, man's ancient dream of turning base metals into gold is not a practical proposition. So it remains a dream!
How big is a tone of gold?
Gold is traditionally weighed in Troy Ounces (31.1035 grams). With the density of gold at 19.32 g/cm3, a troy ounce of gold would have a volume of 1.64 cm3. A tone of gold would therefore have a volume of 51, 760 cm3, which would be equivalent to a cube of side 37.27cm (Approx. 1' 3'').
Where does the word Gold come from?
The word gold appears to be derived from the Indo-European root 'yellow', reflecting one of the most obvious properties of gold. This is reflected in the similarities of the word gold in various languages: Gold (English), Gold(German), Guld (Danish), Gulden (Dutch), Goud (Afrikaans), Gull (Norwegian) and Kulta (Finnish).
Who owns most gold?
If we take national gold reserves, then most gold is owned by the USA followed by Germany and the IMF. If we include jewellery ownership, then India is the largest repository of gold in terms of total gold within the national boundaries. In terms of personal ownership, it is not known who owns the most, but is possibly a member of a ruling royal family in the East.
How much does a gold bar weigh?
Gold is made into a large number of different bars of different weights. The most well known are the large 'London Good Delivery Bars' which are traded internationally. These weigh about 400 Troy Ounces, i.e. 12.5 kg/ 27 lbs. Each. Others are denominated in kilogram's, grams, troy ounces, etc. In grams, bars range from 1 g up to 10 kg. In troy oz, from 1/10 tr.oz. up to 400 tr.oz.. Other bars include tola bars and Tael bars.
Checklist when Testing Gold Chains
- Look for hallmark
- Check to see if chain is magnetic
- File into piece to get through plating /overlay or to expose sterling underneath.
- Test with Nitric Acid or your electronic tester
- Beware of any 18 Karat White men’s chains
Steps to find fake chains
- Hallmark. When testing a chain look for the hallmark first. We have found that the fake chains will have a Karat stamp like 14K but not have a manufacturer hallmark.Your chain manufacturers are going to put the company hallmark on their piece.
- Magnetic. The next step would be check to see if it is magnetic, this will tell you right away you have a no value chain.
- Nitric Acid. When testing with nitric acid or an electronic tester remember to file into the piece if you can, this will get through any plating or gold overlay. Always test body of chain not end caps or clasp.
Nitric Acid Reactions
Below are some reactions to look for when using the straight nitric acid method.
(Be sure to wear eye protection)
- 10 Karat Yellow - Brown color
- 14KY - Very slight brown color
- 18KY - No color change
- 10Karat White - Dark brown, after 20 seconds the acid starts to fizz
- 14KW - Slight brown
- 18KW - Faint brown