Gold Occurrences in Puerto Rico

Coat of Arms of Puerto Rico

Its very name in English means Rich Port and yes there is gold in Puerto Rico.  Over seventy years before Puerto Rico became an American Possession the Spaniards established a mine on the Mami River that the first Americans found as ruins in 1898.  This old mine was discovered by W.A. Shoemaker who was traveling all over the island in behalf of the American Association of Manufacturers and the Philadelphia Commercial Museums on a commercial investigation of the island and its resources while on the outlook for possible commercial ventures.  The old goldmine on the Mami River was one of his discoveries.

Gold was discovered in the Central Highlands of Puerto Rico in the early 16^th century and there were several gold mines operating until the end of the 16^th century.  For many centuries gold mining was missing from the Island and wasn’t revived until 1828 when a mine was established once again in the Central Highlands.  

Gold was the first economy established on the island that was shipped to Spain when it was mined.  These mining ventures were built on the backs of the Taino Indians who several times revolted against their Spanish conquerors until their survivors were driven to the interior of the island where many of their women were taken as wives by the Spanish sailors finally creating the present day Puerto Ricans. 

Gold is found in five different types of deposits on the island of Puerto Rico as placer deposits, copper skarns, porphyry copper-gold deposits and acid-sulfate precious metal deposits.  It is thought by the USGS that there is plenty of opportunity to find additional deposits of gold on the island as well as in the surrounding continental shelves.  While there is no real evidence of these deposits it is possible that there are large bulk concentrations of gold in the intensively acid sulfate altered areas.  Many of the skarns are accompanying tertiery intrusives and in many of the polymetallic veins found in Puerto Rico and its offshore areas.

The first gold deposits worked by the Spaniards were probably placer gold.  These deposits can be found associated with all the major rivers on the island that drain north from the Central Highlands.  Although these deposits are mostly small it has been estimated that they may aggregate as high as 1 million ounces of gold.  There are also placer gold associated porphyry copper-gold deposits of the Utuado District where it is found in the small drainage basins of the surrounding area.

It is also thought that several underground placer deposits could be hosted in the many caves in the karst topography found on the north side of island.  Although these deposits are probably small they could also be extensive and for the most part are little explored unlike the surface rivers where there was extensive exploration under the Spaniards during the 1500s.

Gold Occurrences in Saskatchewan

Many of the people living in Saskatchewan don’t realize that the province is the largest producer of Uranium in Canada but also has or had some world class gold deposits that are found in the northern part of the province. The starting point for all this mining activity is the city of Saskatoon where many of these mining companies are headquartered. The potential of the province where the surface geology has barely been scratched is vast with many mineral deposits yet to be found.

Rumors of gold being found by trappers on the North Saskatchewan River started filtering out in 1859. These rumors claimed there were one ounce and larger nuggets being found were prevalent during the building of North Battleford. Flour gold can still be recovered by panning the river from Churchill west to Edmonton Alberta and beyond. Some stories even tell of seeing businessmen with their pants rolled up panning gold from the river during lunch hour around Edmonton Alberta.

Gold was first discovered in Saskatchewan near Prince Albert in 1859 in the North Saskatchewan River. The province began producing gold in small quantities in the early 1900s from placer deposits along the North Saskatchewan River and its tributaries. Today there five gold mines have been brought into production since 1987 with additional production coming from base metal mines mainly from around Flin Flon. There are an additional 200 gold occurrences in the province that are not being worked presently.

During the 1980 although gold had been produced since the early 1900s marked the first time that there had been a significant gold exploration program had been used in the province. Most of these occurrences are in the Precambrian shield area except for some small placer deposits draining off the Canadian Shield.

According to the Saskatchewan Geological Survey (SGS) there are still large areas in the Province that haven’t been explored especially in the Canadian Shield. To search for Saskatchewan occurrences of gold, use the Saskatchewan Mineral Deposits Index searchable database, or the Geological Atlas of Saskatchewan. Or open the Mineral Resource Map of Saskatchewan.http://upload.wikimedia.org/wikipedia/commons/2/2b/Saskatchewan-map.png

It has been pointed out to me by one of my Canadian prospectors whose mother was born in Battleford, SK that they mined placer gold along the Saskatchewan River flowing between Battleford and North Battleford.  Some of the miners reported they were able to recover as much as an ounce a day.

Gold Occurrences in Wisconsin

There is gold to be found in Wisconsin in the forms of placer deposits in just about any county in the state that were brought here by the many glaciers that have come down from the gold bearing regions of Canada. It should be remembered by prospectors that Wisconsin is divided geologically into two different parts that are nearly equal in size. In the southern part of Wisconsin the basement rocks are buried under a deep deposit of sedimentary rocks that in some places can be miles deep. The northern part of the state is a continuation of the Canadian Shield.

Bedrock map of the Lake Superior region.

Gold found in the northern part of Wisconsin comes from both small lode deposits as well as widespread placer deposits. The placer gold is found in just about any stream or river in the state as well as the beaches along the southern shores of Lake Superior. The deposits lode gold all discovered in several places up to this point none of them found were economically viable. There are several mines in the northern part of the state that are producing both iron and other base metals. Geologically there is no reason why gold should not be associated with these deposits. Just across the border in Michigan there is working gold mining that is produced gold for many years. Of interest are the copper mines that are found in the northern part of the state where the operators of these mines were well aware of the presence of gold, but for economic reasons they just didn't raise the issue.

Throughout the whole state of Wisconsin there are glacial deposits of placer gold brought down from Canada that by being reworked by running water for placer deposits. These deposits are found in the rivers and streams wherever there is a sudden change of velocity in the running water, or on beaches of the many lakes in the state where the gold is concentrated by wave action. Gold of this nature is usually found in fine grains and what is termed flour gold that forces the prospector to become very skillful in the use of the gold pan recover this gold.

Glacial Deposits
Photo by Richard Webb

The gold isn't the only thing the glaciers brought down from Canada; they also brought down several gemstones including diamond, ruby, sapphire and zircon. Weight for weight the stones are actually worth more than gold with the exception of zircon. Deposits of these gemstones are often found in placer gold deposits because there are also concentrated by the action of flowing water. Like gold the glaciers scattered these gemstones across the whole state.

A glacier.
Photo by Kristan Hutchison

Anyone in Wisconsin is allowed to do what is termed recreational gold panning without having to have a license as long as the stream banks and bottoms are not harmed or large amounts of silt and other waste products is not released into the waters of the State. Any gold you find belongs to the person that holds the mineral rights on the property where you found it. You must get permission from the property owner before you do any panning by reaching some sort of agreement with the holder of any mineral rights before you start gold recovery. 

Prospecting for Gold in Larger Mature Rivers

A mature river is characterized by a slow flowing current with lots of meanders flowing across a relatively flat plain where the grinding action of the stream load will tend to grind any Gold present into fine particles like flour that are very difficult to recover. Because of this many of the larger streams are overlooked as places where you can find placer gold. However, there are a few places in one of these rivers that might be a profitable place to look.

This is an example of a mature river in Germany, The River Saar.
Photo by Wolfgang Staudt

For the purpose of this discussion we are going to use the upper reaches of the Connecticut River between Vermont and New Hampshire as an example, but the same situation occurs in all large rivers that are located in gold bearing areas.

This is a typical gold bearing stream, Walton Creek in Southeastern Idaho.
Photo by Finetooth 

The first situation occurs at the mouth of a gold bearing stream where it enters the larger river. Since for the most part gold is found along the banks of streams and the edge of water because of its great density it does not like to migrate downstream except under the influence of some fast flowing water that is usually represented by a flash flood or spring freshet. In the case of its entering a larger river there is a sudden drop in the velocity of the current at the mouth of the stream that will cause gold to be deposited at the mouth of the stream and along the water's edge in the larger river.

This is a Spring Freshet on a river in New Brunswick, Canada

The other situation where gold was found is that the larger river encounters a waterfall where the gold in the river is set to be deposited in either the cracks and crevices of the rock that forms the waterfall, or in the plunge pool beneath the falls.

This is a small waterfall flowing over ledge; the cracks and crevices in the rock would be one of the best places to look for gold because it forms a natural trap for gold.  The plunge pool at the bottom of the falls would also be another place to look for gold as all the gold coming down the stream would tend to collect there.
Photo by Liam Higgins

It should be remembered that most gold is transported along a stream by the action of episodes of flash flooding rather than the slower moving currents that are encountered during the summer. This is true of all rivers or streams.

The final place where it might be profitable to search for Gold in a large river is where a floating tree or other debris forms a natural riffle in the bed of the river.

Although you can test for the content of gold with a simple gold pan, but for more serious mining you should use some variation of a sluice box for maximum gold recovery. One of the more effective of these devices is the recently invented GoldCube.

Trace Minerals found with Gold

Forward:

There are many minerals that are found in nature with gold, one of the most common found in placer deposits is small grains of magnetite.  This and other minerals have been used to find gold that can be recovered by the use of the pan.  Other minerals have been used in locating gold in lode deposits.  It seems that gold is often found with other metal bearing minerals including iron. These are called indicator minerals.

Fig. 1 Crystalline gold

Placer Deposits:

Placer deposits are made from the products of erosion if they can withstand the rigors of the weathering process.  Very few minerals are hard and tough enough to survive whole and remain recognizable when they have been reduced to the size of sand grains, around 2 mm in diameter.  The most abundant mineral found in sand is quartz, SiO₂ also known as silica. 

Quartz grains along with other minerals having a hardness of 7 or more on the Mohs Scale of Hardness make up what are called black sands or stream heavies in placer deposits.  Gold is another mineral found in the same environment that doesn’t depend on its hardness to survive in such an environment instead quite the opposite is true.  The ability of gold to survive is its softness and malleability allowing it to survive in placer deposits.

Most of the indicator minerals for gold are . . .

Quartz	Magnetite (Magnetic)	Hematite
Garnet	Beryl	Corundum
Feldspar (Sometimes)	Kyanite	Sillimanite
Topaz	Tourmaline	Mica (Small flakes)
Diamonds	Monazite	Zircon

There are others in the list, but these are the most likely to be encountered.

Lode Gold:

Lode gold is found in solid rock that is often discovered by tracing placer gold back to its source often using the indicator minerals found associated with gold in the gold train, a scattering of gold found away from its source rock.  The further away gold is from its source the smaller the particles become and the more widespread the individual particles of gold become.

Fig. 2 Gold in quartz

Most gold is found in quartz veins where it has been deposited from hydrothermal waters into the older quartz veins.  Much gold has been found in iron pyrite as a contaminant, and ever rarer it is sometimes discovered a “telluride” where it is combined with the element tellurium.

Many of the same minerals as found in sand can also be found in occurances of lode gold, but there are several other minerals that are just too soft to survive the rigors of weathering, they include . . .

Apatite	Calcite	Biotite Mica
Galena	Sphalarite	Chlorite
Feldspar	Staurolite	Arsenopyrite
Amphobolite	Garnet	Iron Pyrite
Pentlandite	Argentite	Granular Magnetite

These are the most common minerals associated with lode gold; there are others.