Gold (Au) is a transition metal between Ag and Rg in the chemical series of the Periodic Table. Its atomic number is 79, and atomic mass 196.96655 (2) g/mol, and has only one stable isotope number 197. The gold isotope 198Au (half-life 2.7 days) is used in some cancer treatments. The metal has been known and prized as an object of beauty and for its unique properties of chemical stability,

Electrical conductivity, malleability and ductility (trivalent and univalent) since

Mankind’s earliest awakenings. As a standard of value against which to appraise

The costs of labour, goods, currency and national economy, it has been the standard of many currencies since the world’s first coinage in Lydia between

643 and 630 BC. The name for gold is derived from the historic English word

`Geolo’, for yellow and the chemical symbol for gold Au, from the Latin name

Gold Mineralization

For gold `aurum’ (glowing dawn). Gold has a long history of use in society so it is no surprise that measurements of gold involve old and somewhat obscure units. Gold is always traded in Troy ounces. Take note: a Troy ounce is not the same as other ounces. 1 Troy Ounce = 31.1 grams because gold is so soft it is often alloyed with other metals in order to improve its durability. Commonly it is mixed with copper, platinum or nickel. Gold alloys are rated using the 24 point carat system. 24 carat gold is pure (100% Au w/w), 18-carat gold is 75% gold by weight and 12-carat gold is 50% gold by weight. The carat system is also applied to Platinum. Just be careful though. This system refers to gold content by weight. Sometimes people assume a given purity to mean the amount by volume. With gold being such a dense material 50% gold by weight does not mean 50% gold by volume! Bullion dealers sometimes quote gold purity using ‘fineness’. 4 nines fineness or 9999 fineness is simply another way of saying 99.99% gold! 4 nines gold is effectively 24 carat gold.

Golden numbers:

1. The Atomic Number of gold is 79. The mass number of the only stable isotope is 197.

2. Gold has 4 synthetic isotopes. Au-195, Au-196, Au-198 and Au-199.

3. Gold is a rare element but it is sometimes concentrated into ore deposits by geological processes. Modern mining and metallurgical techniques have allowed ores with as little as 2 grams per ton of gold to be mined profitably.

4. Gold is very ductile. Some claim that a troy ounce of gold can be drawn out into a wire 60km long. Assuming the wire has a constant circular cross-section.

5. Gold is very malleable. Gold can be beaten into a thin sheet and used to guild the surface of objects.

Gold Deposits in the Mantle and Crust:

Present theory is that gold and other heavy elements would have been evenly spread in the forming Earth. However, the percent of gold present in interstellar matter is extremely minute. As the core melted, gold would amalgamate along with iron and nickel. The silicates floated above the core and formed the mantle which extends from a few miles below the present surface to about 2,000 miles down. It is composed of iron and magnesium silicates called Olivine with minor amounts of other impurities like gold. The surface of the planet is called the crust and is about 20 miles thick under the continents. Below the oceans, the crust is much thinner or completely absent. The crust differs from the mantle in that the rocks are made up of the elements sodium, magnesium, aluminum, and calcium.

Gold is present in the crust and mantle in very low concentration. Tests on California granite show an average of 0.103 parts per million, which works out to 0.003 ounces per ton. T.K. Rose, in his book, “The Metallurgy of Gold,” cites a number of assays on rock samples taken from locations remote from known gold deposits. The values range from 0.03 ounces to 0.003 ounces of gold per ton.

High grade lode gold sites which have been worked in the past are the result of hydrothermal concentration or organic deposition.  Hydrothermal concentration is the leaching of deep mantle rock by water from the surface of the planet. Under the ocean, those geysers found during the last few years are evidence of this process continuing into the present time. Seawater seeps down into the mantle where it is heated and makes contact with the olivine rock. This rock contains small amounts of gold, manganese, and cobalt and larger quantities of iron and sulfur. These are leached from the rock and the heated seawater begins to rise until it finds a vent where it returns to the sea and deposits the sulfides of these metals as it cools. The process is the same on land; and many of the world’s gold deposits were created from this process. The hydrothermal solutions at work on land are evident at Yellowstone National park where “Old Faithful” spews its lode of mineral-rich water on the hour, and hundreds of hot springs and mud holes smell of the sulfur-rich mineral they are bringing to the surface.  Organic deposition is similar to the carbon recovery from leach solutions which is used so much today. Ocean water contains gold in varying amounts; but the average is something like 120 to 130 tons to the cubic mile of sea water. If this solution is passed through previous rock or gravels containing organic matter, some of the gold will be deposited on the carbonaceous material. The gold reefs of South Africa were probably derived from this process. T. K. Rose theorizes in his book that much of the gold deposited in sedimentary rocks was by the process of adsorption on carbonaceous material.