All That Giltters
Is Not Gold
It could be diamonds, gemstones, platinum, pearls, rubies, sapphires, emeralds,
rings, necklaces, pendants and gold chains |
|
About Gold |
 Description: Gold is usually found in hydrothermal
deposits where it forms at a wide range of temperatures and
geological settings. Gold may form in exhalative deposits formed
on the sea floor associated with Archean basaltic sequences
known as greenstone belts. It may form in veins associated
with large granite intrusions associated with mountain building.
It may also form in veins formed along major fault zones. Gold
in veins is associated with sulfides, quartz and calcite.
Gold is resistant to weathering, hence is often freed from the surrounding rock
and redeposited as sediment. Because gold has a high density, it tends to settle
out readily and be trapped with coarser sediments. Where current action is strong,
less dense materials are preferentially washed away, concentrating the gold in
placer deposits. In submerged gold-bearing sediments, slight shaking of the sedimentary
column will cause the gold to sift down toward the bottom of the deposit. These
tendencies result in the gold accumulating along the contacts between sediment
and underlying bedrock. Cracks and crevices in bedrock over which a river rushes
or has rushed are good places to prospect. In placers, gold is associated with
other dense or "heavy" minerals such as garnet, magnetite, ilmenite,
and even diamonds. Gold is also found in conglomerates that are lithified placer
deposits.
Gold has been reported from a number of localities in Wisconsin, but the known
deposits are all small and sub-economic. In researching gold reports one has
to realize that salting and fraudulent reports do occur and misidentification
of materials such as pyrite and even bronzy-colored biotite for gold is common.
It is also true that the locations of suspected gold mines might be vaguely located
or deliberately mislocated in the literature.
Gold in small amounts can probably be found in placers in any county. Wisconsin
glacial sediments contain small amounts of gold, and most of Wisconsin streams
are reworking some glacial sediment. Weekend panning can be a fun recreational
activity, as long as one's expectations for valuable finds are not too high.
Wisconsin drift gold is generally in very small particles, constituting what
is termed "flour gold", with true nuggets being exceedingly rare. As
such, skill and practice are necessary in being an effective "panner".
The associated sand-sized "heavy minerals" such as red garnet and black
magnetite sand are interesting in their own right. Rarely, diamonds may also
turn up during gold placer mining, as was the case along Plum Creek in Pierce
County.
Check with the Wisconsin D.N.R. and property owners before doing any panning
in Wisconsin. |
* Gold primarily occurs in lode deposits. The source
of lode deposits is not known for certain, but there are
3 main hypothesis proposed by geologists to explain them.
*
One hypothesis suggests that circulating ground waters, heated
by bodies of magma, intrude back into the Earth's crust.
The heated water causes minerals in surrounding rocks to
dissolve. As the heated water and dissolved minerals reach
shallower and cooler rocks, the water itself cools and the
minerals precipitate out into veins and blanket-like ore
bodies.
* Another hypothesis proposes that gold bearing solutions
are present in cooling magma. As the magma moves upwards
through the Earth into lower temperatures and pressures,
the solutions are expelled and cooled, precipitating ore
materials.
* The third hypothesis suggests that gold-bearing sedimentary
and volcanic rocks undergo metamorphism during mountain building
processes. During metamorphism, water is squeezed out of
the rocks. As it travels away, the water deposits ore materials
as pressures and temperatures decrease.
* More details and some diagrams on these types of deposits
*
Gold also occurs in placer deposits. The deposits occur when
gold flakes, nuggets, and grains are eroded from lode deposits
and carried downstream. When the current slows, these gold
particles settle in depressions in sand and gravel bars.
These are the types of deposits prospectors look for when
panning for gold.
* Gold may also be found in small inclusions
in pyrite or other sulfides, as well as quartz veins in low-grade
metamorphic rocks, granitic rocks, and contact metamorphic
rocks.
* One of the most visible, everyday uses of gold is
in ornaments and jewelry.
* Because it is so malleable, gold can also be used as a thin coating on objects,
known as gold leafing.
* Gold has also been used for centuries to create priceless
artwork, such as these examples from Costa Rica, dated around
500-1550 AD. (more information on these artworks)
Because of its limited supply, gold has long served as
unit of monetary exchange in coins and bullion.
Gold has
also become extremely valuble in industry. Due to its conductivity, its malleability,
and its freedom from tarnish and oxidation, gold is used in many electronic applications,
such as computers and home appliances.
* Gold has been used
as a standard treatment for rheumatoid arthritis since the
1960's, and is now becoming important in other areas of health
and medicine such as surgery and lasers.
* Gold is also sometimes used in dentistry. |
| Color |
This property results from the response of the eye to the visible part
of the electromagnetic spectrum. |
-
Pure gold appears as gold-yellow.
-
When alloyed with silver, it is a lighter color than pure gold
-
When alloyed with copper, gold has a reddish color.
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| Luster |
This property describes the quality of light reflected off the mineral.
(Pictures
of some different types of luster) |
Gold has a metallic luster. |
| Streak |
This is the color of the powdered mineral. |
The streak of gold is the same as its color. |
| Hardness |
This is a measure of the mineral's resistance to scratching. |
Gold has a hardness of 2.5 - 3 on Moh's
scale of hardness. |
| Cleavage |
This is the property of a mineral to break along planar, crystallographically
controlled surfaces. |
Gold has no cleavage. |
| Tenacity |
This describes the manner in which a mineral deforms under stress. |
Gold is sectile and malleable. |
| Specific
Gravity |
This is the ratio between the weight of the mineral and the weight
of an equal volume of water at 4°C (abbreviated G). |
For gold, G = 19.3 |
| Habit |
This refers to the style of crystal growth. (Pictures
of some different types of habits) |
Gold can have many different habits including reticulated, branching,
platy, filiform, spongy and massive. |
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As a native element and a precious metal, Gold is a rare
and highly valued mineral. It has been used by mankind for
thousands of years, and is still widely used today in a variety
of fields ranging from from decoration to economics, to medical
and industrial technology.
The chemical symbol for gold is Au. It's composition is
usually pure gold, but it may sometimes form alloys with silver, copper,
or other metals. An alloy of silver and gold with an intermediate
composition is called electrum.
In Europe 18 and 14 carat alloys are most commonly used
in jewellery, however 9 carat is popular in Britain.
In many countries the law requires that every item of gold
jewellery is clearly stamped with its caratage. Jewellery
in many countries is stamped or hallmarked with its caratage.
The hallmarking system was developed in London in the 14th
century at Goldsmiths' Hall. |
Gold is so rare, only 90,000 tons of it have been taken
from the earth in recorded history.
Gold is so rare that the world pours more steel in an hour
than it has poured gold since the beginning of time.
South Africa leads the world in gold production. Other countries
leading world production are Russia, Canada, and the United
States.
Gold is so heavy that one cubic foot of it weighs one half
a ton.
A one ounce natural gold nugget is rarer than a 5 carat
diamond.
Experts estimate that there are only 41,000 tons of gold
left in the earth to mine.
Gold is so malleable and soft that one ounce can be stretched
into a wire 50 miles long.
Gold is so malleable that one ounce can be hammered into a
sheet so thin it would cover 100 square feet.
Gold has lustrous beauty, it’s easily workable, it is
rare, and it is virtually indestructible - four characteristics
that no other precious metal possess.
The jewelry industry uses about 1,000 tons of gold per year
and dentistry uses 87 tons.
All the gold in the world could be compressed into an 18 yard
cube.
Gold has been used by man for more than 66 centuries, In fact,
the first nugget mined, now over 6,000 years old, probably
exists in some form today because of its durability, considering
the way gold is remelted and recast, that first nugget could
be part of a ring, watch, or gold chain that you are wearing. |
Jewelry Terms Explained
BAIL: device used to hang a piece of jewelry from a chain.
Referred to as a rabbit ear bail or loops. Always soldered
when used in nugget jewelry.
CARAT: unit of measure for gemstones and diamonds, abbreviated
ct. or Ct.
CASTINGS: items made from special molds, using 10,14 or 18
karat casting grain, it takes special casting for gold nugget
jewelry.
CLASP: device used to close & secure a piece of jewelry,
such as a spring ring, lobster claw, pearl catch, safety, etc.
FINDINGS: items used to make up jewelry, such as clasp, chains,
settings, wire, castings, earring posts, bails, loops and so
forth.
FINE GOLD: pure, 24 karat gold metal or bullion, not found
in nature.
GOLD FILLED: layer of gold mechanically applied and welded
to both sides of a base metal, thicker than gold plating .
a gold sifterGOLDSMITH : person that specializes in the manufacture
of gold jewelry, and/or other articles made with gold and it’s
alloys. Most of work done by hand.
JUMP RING: finding made from gold or silver metal that is
used to connect one part of jewelry to another part, such as
a jump ring would be put between the chain and the clasp. Can
be round or oval shaped, any size, and use any gauge wire.
Always soldered when used with nuggets.
KARAT GOLD: measure of gold purity, expressing the proportion
of gold in alloy. One karat is 1/24 part of pure gold, which
is too soft for everyday jewelry, and the alloy is silver with
small traces of copper. Hardens gold so it wears longer. Designated
as Kt. 14Kt. Is 41.6% gold, 18Kt. Is 75% gold, 22Kt. Is 91.6%
gold.
MOUNTING OR SETTING: device used to hold gemstones in place,
may be a 4 or 6 prong head mounting, or a bezel mounting that
has metal all the way around the stone, and may be in any shape
the gemstone comes in.
NECKLACE: multiple nuggets, gems, pearls or gold with pieces
of chain, wire or bead stringing wire between each piece. Can
be a string of pearls or beads.
PENDENT: single piece of gold, gemstone or nugget suspended
from a chain or wire, that is worn around a persons neck.
an old scale SHANK : casting for rings, watchband or other
jewelry that gold nuggets are soldered to.
SOLDER: that chip or paste of 10 or 14 karat gold that is
placed between two pieces of gold and heat is applied to melt
the solder, permanently joining the two pieces of metal. Same
as welding, just much smaller.
TROY WEIGHT: unit of used for precious metals such as silver
and gold, broken into grains, pennyweights and/or grams as
follows: 24 grains = 1 pennyweight (it takes 1.6 grams to equal
one pennyweight) 20 pennyweights = 1 troy ounce (it takes 31.2
grams to equal one troy ounce. 12 ounces = 1 troy pound.
links |
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