History
Gold was known and highly valued from earliest times. Egyptian
inscriptions dating back to 2600 B.C. describe gold and gold is mentioned
several times in the Old Testament.
Properties
Gold is usually alloyed in jewelry to give it more strength, and the term
carat describes the amount of gold present (24 carats is pure gold). It is
estimated that all the gold in the world, so far refined, could be placed
in a single cube 60 ft. on a side. It is metallic, with a yellow color
when in a mass, but when finely divided it may be black, ruby, or purple.
It is the most malleable and ductile metal; 1 ounce (28 g) of gold can be
beaten out to 300 square feet. It is a soft metal and is usually alloyed
to give it more strength. It is a good conductor of heat and electricity,
and is unaffected by air and most reagents.
The most common gold compounds are auric chloride (AuCl3) and chlorauric
acid (HAuCl4). A mixture of one part nitric acid with three of
hydrochloric acid is called aqua regia (because it dissolved gold, the
King of Metals). It is unaffected by air and most reagents.
Sources
It is found free in nature and associated with quartz, pyrite and other
minerals. Two-thirds of the world's supply comes from South Africa, and
two-thirds of USA production is from South Dakota and Nevada. Gold is found in
sea water, but no effective economic process has been designed (yet) to
extract it from this source.
Uses
The following uses of gold are gathered from a variety of sources.
- Coinage metal, standard for monetary systems in many countries
- Jewelry, decoration
- Dentistry
- Plating. It is used for coating space satellites, as it is a good IR
reflector and is inert
- Chlorauric acid (HAuCl4) is used in photography for toning the
silver image
- Disodium aurothiomalate is administered (intramuscular) as a
treatment for arthritis
- Electronics
- Photography for toning silver images
- 198Au is used for treating cancer and other conditions
Fabrication and Forms
H Cross Company can provide Gold in the standard 99.95% commercially pure
grade in wire sizes from .005" diameter up to .100" diameter, strips and
ribbons from .0005" thick to .020" thick and from .020" to .100" wide and
in sheet or foil form from .0005" thick to .020" thick and up to 2" wide.
Please
email us if you have needs outside of these ranges, as we will
always try to be of assistance for your specific requests.
Packaging
Each H. Cross Company product is delivered in packaging specifically
designed for the product's application. As an example, wire is furnished
on returnable plastic reels, each containing a single length of wire.
Strips, Ribbons, Sheets and foils are flat packed to prevent damage during
shipping. If required, H. Cross Company can adapt standard packaging
methods or develop new ones for your special needs. |
