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Sunday, February 27, 2011

An Auction Site for Used Gold Mining Equipment

This is an old fashioned gold pan that is still in use today.

What this country has needed for a long time is a good nickel cigar, or a place where you can buy and sell used mining and prospecting equipment in a single website. We may wait quiet while for a nickel cigar, but there is now a website where you can buy and sell used Gold Mining equipment in an auction. The name of the new service is prospecting -- that can be reached at:

They bill themselves as the 1st auction site on the net for gold prospecting gear. They have all equipment, tools, supplies and gear. Be sure you check their gold giveaway page for the latest thing in giveaways. Another page on the site is about gold-mining info and metal detector manuals. The site also contains equipment reviews and free plans for building your own gold-mining and prospecting equipment.

Friday, February 25, 2011

The World of Volcanogenic Massive Sulfides (VMS)

As a source of gold volcanogenic massive sulfides are not the primary source, but they do contain a substantial amount of gold as a byproduct. These deposits also hold significant amounts of copper, lead, zinc as well as gold and silver. Throughout history the VMS deposits are generally not the first choice of miners, as they are usually small and can be difficult to process. In today's world they have become a more significant source of metals than they were in the past because of advances in technology as well as the recent high metal prices that have caught the attention of prospectors.

This is Rouyn-Noranda the home of a VMS deposit. The Horne Smelter is in the background.

Deposits of VMS minerals can take in a variety of shapes occurring typically as lenses of polymetallic massive sulfide subform in patches on the seafloor near black smokers. Deposits of this nature can be found in extensional tectonic settings that include both spreading from the tectonic ridge, or can also be found in back arc basins such as the modern Sea of Japan. They range in age from some of the oldest rocks on Earth to the modern black smokers that are found in oceanic spreading centers.

Many deposits of this type that were once on the ocean floor have been incorporated in the continental crust by tectonic earth movements, so they are now on land. Even with the location of many of these deposits on dry land there are still many other exploration and mining companies that are interested in recovering minerals from the seafloor VMS deposits.

A black smoker where VMSs are formed in the Atlantic Ocean

Deposits of the VMS type are grouped according to the type of rock they are hosted in or on the basis of ore composition. This type of deposits can be classified in three different ways.

1. These are felsic volcanic hosted making up the most popular category that accounts for at least 50% of the deposits. Examples of this type of deposits can be found in the Abitibi region of Canada in Québec and Ontario.

2. These are mafic volcanic hosted accounting for about 30% of the deposits,

3. These are interbedded with a mixed bag of volcanic and sedimentary rocks that account for an additional 20% of VMS deposits.

The ore found in these deposits is broken into two groups: copper, zinc and zinc, lead and copper they also contain significant amounts of gold and silver.

Prospecting on an Ancient Spreading Center

A tectonic ridge is associated with a spreading center where magma from the bowels of the Earth reaches the surface where it is the driving force for plate tectonics. The same feature is also the home of black and white smokers the source of many mineral deposits. For the most part tectonic ridges are found in the ocean deeps usually a depth of about 12,000 feet, but an exception is made for Iceland where the tectonic ridge is exposed on the surface of the land. Iceland is also one of the most volcanic areas on earth with the exception of the Ring of Fire that encircles the Pacific Ocean, but that is caused by just the opposite environment where tectonic plates are plunging beneath other plates in subduction zones.

Black smokers emitting clouds of metal sulfides.

The smokers are the result of ocean water penetrating deep into the oceanic crust that is composed of basalt, and leaching out the various metal ions and expelling the from the surface and clouds of metal sulfides. These sulfides are deposited in a particular sequence depending upon their solubility in water copper and iron are usually the first sulfides that are deposits and the other metals are deposited according to the  solubility of their sulfides.

Kidd Creek Mine in Timmins, Ontario

Although deposits of this nature are formed in the depths of the ocean is theorized that because of plate movement these deposits can eventually be incorporated into continental plates. A good example of this type of deposits is the Kidd Creek Mine located in Timmins, Ontario or the Horne Mine in Rouyn-Noranda, Quebec.

Thursday, February 24, 2011

The Price of Tungsten reaches Historic Highs

A metal that has so many unique properties tungsten is invaluable in many industrial applications. Tungsten has the highest melting point of all the elements except carbon, and its density is higher than lead. When you dissolve tungsten in carbon you end up with a product called tungsten carbide capable of being used in the machining trade as cutting tools and drills. In the mining industry is used to manufacture carbon button drills for both petroleum and mining uses. In military applications tungsten carbide is used as the core of armor piercing artillery rounds, and rocket nozzles because it is capable of standing up to the high temperatures involved. This is another metal that the world is coming to depend on China for most of its supply even though its ores that are widespread are considered to be gangue for many other metals including gold.

A sintered tungsten bar.
Photo by Jurgii

Like rare earth metals China has lowered its export quotas for tungsten since 2008. This year it has been lowered to the extent the quota stands at 15,700 tons, this is a reduction of 300 tons over the year 2010. This has resulted in an extremely tight market for the metal along with increased demand has sent the prices as of February 23 to $50 per kilogram representing a new all-time high.

China has ceased exports of concentrate, and Rob materials, but they will export semi-refined and refined powders. In the years 2004 in five the recycling component of tungsten was only around 5%, but it has reached as high as 35%. While the Chinese limited the amount of tungsten coming to the world market the results of this recycling effort has acted as a buffer, but now it has reached the ceiling.

A rotary hammer drill bit with tungsten carbide inserts.

The cause of the present shortages can be laid to low prices as well as a lack of buyers that forced many tungsten miners to cease production. When the market started coming back the inventories of the model were quickly depleted. This caused the initial attempt to restock while the balance between recycled tungsten increased just as the amount of exports from China dwindled. This is caused a sudden spike in the cost of tungsten.

Prospecting Ancient Tectonic Ridges

The ridge is at the center of a spreading zone where magma being erupted through the ridge causes spreading that is usually seafloor; one exception is Iceland where the ridge is exposed on dry land.  A ridge is also the home to “black smokers” that are the surface manifestation of leaching minerals from the oceanic crust.  It is fine metal sulfides that cause the smoke like effects when the hot water cools enough to cause these minerals to precipitate where they are deposited in chimney like structures around the black smoker.

The Kidd Creek Mine in Timmins, Ontario an example of a volcanic massive sulfide deposit.

 When these sulfides are deposited they persist for billions of years creating mines that are termed “Volcanogenic Massive Sulfides” (VMS).  Some of the greatest metal sulfide deposits on earth are of this type.  There are many examples of deposits of this type around the world two of them are found in the Abitibi region of  Canada the Horne mine is Rouyn-Noranda, Quebec and the Kidd Creek mine in Timmins, Ontario.

Wednesday, February 23, 2011

Sand and Gravel

According to the USGS sand & gravel is one of the most accessible natural resources in the United States second only to crushed stone in value.  It has had an explosive growth rate since the beginning of the 20th century when relatively little was used.  Sand and gravel is mainly used in the construction industry in the form of construction sand & gravel mainly used in the production of concrete and in bituminous concrete (blacktop).

A sand & gravel pit
Photo by Roger W. Hayworth

Annual production of sand & gravel in the United States today it ranks as second in tonnage in the non-fuel minerals after crushed stone.  It is the only mineral commodity that is produced in all fifty states.  In general the United States is self sufficient in the amount of sand & gravel that is produced annually by producing enough to meet all its domestic needs, and is a small net exporter mainly to places where sand & gravel is used to a certain extent in the areas along the borders with Canada and Mexico.
Demand for sand & gravel is mainly controlled by the level of construction activity that controls its demand.  In the United States the production of sand and gravel has grown significantly since the end of WW II with production in 1950 at 320 metric tons increasing to  approximately 900 million metric tons by 2000.  The level of production has dropped since that time.

Sand that has been processed and stored
Photo by Claus Ablieter

Mining sand & gravel is mainly a clean operation in comparison to your local corner bakery although to many people it is unsightly.  This has led to a great misunderstanding on the part of the general public where the perception is that sand & gravel mining is harmful to the environment.  This has caused many sand & gravel deposits to be withdrawn from mining for demographic reasons that in many areas has caused shortages of sand & gravel to occur.
Sand & gravel is a product having a high in-place value that considering the present business conditions costs approximately 50 cents per ton mile.  The further it is necessary to transport the material the more it costs.  Sand & gravel that costs less then $2.00 to produce per ton is apt to cost more then $20.00 per ton delivered. 
A great deal of the problem that was the cause of a special investigation by the governors of the Northeast States was brought about by the mistaken perception that sand & gravel mining was environmentally hazardous; it isn’t.  This misplaced perception has done nothing more then increase the cost of virtually all construction projects throughout the United States.

All that’s precious is not Gold

Platinum crystals, platinum is often found with gold.
Photo by Jurii

All that's precious is not gold it by any means there are other things we can search the earth for their evening more precious than gold. This includes the platinum group metals (PGM) as well as precious gems. In the course of prospecting for these we often concentrate on gold but there are other things that we might run across in our searches that ultimately can yield more money than gold. We are going to include articles about these other precious things in this Blog in the future.

The Cardinal Gems that by weight can be more precious then gold.
Photo by Rob Lavinsky

Gold Occurrences in Pennsylvania

Pennsylvania has a long and rich tradition of mining especially for anthracite and bituminous coal as well as iron. What is not generally known however is the state is also produced a considerable amount of gold. It has a well-trained workforce of miners many of whom have a tendency to be prospectors. Because of this some iron miners down around Cornwall have actually produced more than 61,000 ounces of gold while they were mining the magnetite iron ore. Aside from the mine at Cornwall another mine that reportedly produced gold from magnetite was the Grace mine in Morgantown.

There were a series of three openings to the iron deposit in Cornwall located at Big Hill, Middle Hill and Grassy Hill that were originally owned by the Cornwall Ore Banks Co., but were eventually owned by Bethlehem Steel who eventually closed the mines in 1979.  This deposit of magnetite was produced by the replacement of limestone by hydrothermal activity during the Jurassic from a diabase intrusive, so in effect the deposit is a skarn.

The eastern part of the state is covered with crystalline rocks producing potential gold lodes as well as placer gold. This gold weathers out of the crystalline rocks and is collected in the rivers and streams of eastern Pennsylvania. This is not the only source of gold however, in the northern part of the state the last glacier left placer gold in the terminal moraines found in Pennsylvania.

There are several streams producing placer gold that came in Lancaster and York Counties in glaciers that have advanced into the state during the past million years. Any of these glaciers were capable of bringing gold down from Canada where one of the richest gold belts the world the Abitibi is found in Québec and Ontario. According to some geologists there have been as many as 24 episodes of glaciation that have affected the northern part of the United States in the past 2.5 million years.
Although the eastern part of the state is mostly covered with crystalline rocks that produce gold as lode gold that weathers out so it becomes placer gold that collects in the rivers and streams found in eastern Pennsylvania.
One of the places where gold has been found is along the Susquehanna River where it has been found as both nuggets and flakes of gold. Generally Wyoming County has been a good place to look for gold as well as in the surrounding counties.  In York County  placer gold is associated with the deposits of diabase that make up the tops of many ridges. The action of weathering releases the gold from bedrock allowing it to migrate downhill into the streams and rivers in the area.
During the Civil War the great battle at Gettysburg was fought on some of these diabase ridges with names like Little Round Top or Cemetery Ridge. There is no doubt that the rivers and streams around the Gettysburg Battle Site undoubtedly contain gold. 
The best way to find out where the gold is in Pennsylvania is to research old newspapers and town histories.  The state only keeps track of commercial mining operations and not that of individual prospectors. Old newspapers are often the source of stories about where one of the local citizens has found gold in their town.
Helpful Links:

There are several gold prospecting clubs that are active in Pennsylvania that can supply more information about Pennsylvania gold.

Our thanks to Stephen Shanks of the Pennsylvania Geological Survey for additional information.

Monday, February 21, 2011

The Association of Gold and Magnetite

One common type of gold deposit is one where the gold is associated with the mineral magnetite where the gold is formed in skarns of granular magnetite.  The mineral has a chemical formula Fe3O4 that is often found in contact metamorphosed areas associated with intrusions of magma into carbonate or silico-carbonate rocks the intrusion itself is usually granite or monzonite-syenite. In such deposits the common minerals that are found include pyroxenes, amphiboles, garnet and lesser amounts of scapolite, vesuvianite and other silicates, but the most important is magnetite. 

Chalcopyrite deposited on magnetite.  The magnetite is the black crystals.
Photo by Rob Lavinsky

In the field magnetite is one of the most easily found of all minerals because it is magnetic and is attracted to a magnet; some of this mineral possess weak magnetism itself, so it is called lodestone.  The ancients were aware of this, and used it to make the first primitive compasses from magnetite carvings many of which looked like spoons whose handle pointed north. 

To prospector the first Association of gold and magnetite occurs in the bottom of your cold pan in the form of black sand that contains small specks of gold. This black sand along with other heavy minerals is considered to be ore in its own right, and is often refined away from streamside to recover its gold content.

Magnetite crystals in a matrix of feldspar.
Photo by Rob Lavinsky

Gold bearing magnetite may be found in massive deposits where the gold is often invisible to the naked eye with the gold often being disseminated throughout the entire deposit of magnetite. The lower bodies in this type of deposit can be presented as one in particular, tubular or more rarely as sheet deposits.

The sulfide minerals found in such a deposit are usually secondary in nature that have been deposited by mineral laden hydrothermal waters. In some deposits of this type goals is also associated with the sulfides, particularly arseno-pyrite as well as other sulfide minerals.

If gold is present in one of these deposits it is not to be disseminated through the body of the rock and quantities that are so small much of the gold is invisible to the naked eye, or there may be small specks of gold that are visible. The usual tenor of this sort can vary from that measured in grams to about 4 ounces per ton.

A great deal of gold can be recovered from magnetite because of the vast quantities of four that are present coupled with the recovery of gold values using the heap leaching process that takes advantage of the ability of sodium or potassium cyanide to dissolve gold. As a rule of thumb that takes approximately 2 ounces of cyanide in solution to treat gold over in this manner. Cyan night is extremely poisonous as it only takes 2/10 of a gram to kill a person. It also presents some very serious environmental issues that have to be addressed. If the proper environmental safeguards are in place the use of cyanide for gold extraction is extremely cost-effective. 

Thursday, February 17, 2011

Gold in Greenstone Belts

Gold is often associated with greenstone belts that according to geologists are a group of variably metamorphosed mafic to ultra mafic volcanic sequences that are often associated with sedimentary rocks that can be found in Archean and Proterozoic terrenes where they are found nested in between bodies of gneiss and granite.

An openpit gold mine operating in a greenstone belt in Australia

The name greenstone comes from the greenish color that is present in many of the metamorphic materials that are found in the rocks composing a greenstone belt. This color is often imparted by actinolite, chlorite and other green amphibole minerals that are typically found associated with these green colored belts of rock.

Many geologists feel that the gold found in greenstone belts is leached from the greenstone by supercritical water to be deposited in the surrounding rocks in quartz veins or as disseminated gold.

Pillow lava typical of that found in a greenstone belt.
Greenstone belts are typical of continental cratons that can range from as little as several dozen to several thousand kilometers in length. Most greenstones contain a great number of individual rock units that is considered a stratigraphic grouping in its own right when they are found on continental sized scales. They are considered by geologists as basically metamorphosed volcanic belts that are associated with ancient oceanic spreading centers or is even island arcs.

Although greenstone belts are usually composed of volcanic rocks with the most prevailing being basalt there are also small amounts of sedimentary rocks that are interwoven, or interleaved with the various volcanic rocks. One of the most common rocks associated with greenstone belts is conglomerate that is often gold bearing as it is in the Abitibi Greenstone Belt in Canada.

The following list of greenstone belts shows how pervasive they are worldwide:


Taishan greenstone belt (Southeast Asia)

[edit]North America
Abitibi greenstone belt (Quebec/Ontario, Canada)
Bird River greenstone belt (Manitoba, Canada)
Flin Flon greenstone belt (Manitoba/Saskatchewan, Canada)
Hunt River greenstone belt (Newfoundland and Labrador, Canada)
Isua greenstone belt (Southwestern Greenland)
Temagami greenstone belt (Ontario, Canada)


Wednesday, February 16, 2011

The Role of Supercritical Water in Forming Gold Deposits

Supercritical water or hydrothermal water is found several kilometers below the earth's surface when the pressure of the overlaying rocks exceeds 220 times more than the atmospheric pressure at sea level as well as elevated temperatures up to 600°C. Water at this temperature is considered supercritical and does not behave like ordinary water; at this temperature water is capable of dissolving most minerals in the surrounding rock including gold.

You could liken supercritical water to water that has been heated in a pressure cooker except it reaches far higher temperatures and pressures than can be reached on your kitchen stove. At these extreme pressures and temperatures the water ceases to act like ordinary water instead it becomes far less dense than water and capable of going places where ordinary water can't go. At the same time it is also capable of carrying large amounts of dissolved minerals that are carried essentially upwards until they reach a place where the temperature or pressure has dropped enough to cause their precipitation. 

Another cause of this precipitation is if the mineral charged waters strike a type of rock such as limestone or quartzite that causes a reaction with the supercritical water causing certain minerals to fall out of solution. It is supercritical water that is the driving force behind metamorphism and all its processes.

Gold in Quartz from Jamestown District, Boulder County, Colorado
Photo by Rob Lavinsky

Generally supercritical water works with carbon dioxide and sulfur that also create large deposits of metallic sulfides that are termed Volcanogenic Massive Sulfides (VMS). In very deep water such as that found in the deeper parts of the ocean supercritical water can be exhausted into the open water where it precipitates large clouds of metallic sulfides in a feature that scientists call “Black Smokers

Most of the gold this precipitation by supercritical water is between 100° and 200°C that is about the temperature at which the metamorphic rock slate normally forms. The gold is often found in quartz veins that intrude the beds of Slate.

Another type of gold deposit that can occur as a result of being precipitated from supercritical water is the so-called Carlin type of ore deposit where the gold is disseminated through the rock in specs so tiny they can only be seen with an electron microscope and may consist of this little is one ion of gold.

A similar situation is found in quartzite that has been stained by supercritical water passing through the sandstone in leaving behind a whole suite of minerals that can very often not be seen to the naked eye. This is especially true if the quartzite shows any form of yellow or even better green staining.

Black Smoker with clouds of metal sulfides surrounded by supercritical water
If you are finding classy looking quartzite without any staining at all you can be almost sure that it is barren of any mineralization including gold. One of the things you should examine further is any quartzite that has been stained yellow or green. This is especially true if the quartzite is in a contact deposit close to an igneous intrusion where often form a halo around the intrusion. This type of deposit is called a skarn that can contain all kinds of mineralization including gold.

Tuesday, February 15, 2011

Gold Occurrences in Madagascar

Although in the past Madagascar was a significant gold producer but because of its tumultuous political history for many years it remained in the doldrums. Today Madagascar is considered to be an up-and-coming place for mining now the political situation has become more stable. Today Madagascar has become a beacon for the mining and exploration industry that right now is largely undeveloped.

Madagascar is shown in red.

For those who don't know where Madagascar is, is approximately 400 km due east of the African mainland. It is separated from Africa by the Mozambique Channel.

Although the island has a vast potential for hosting valuable mineral deposits right now the country does not have a well-developed mining industry. As little as 30 years ago it was one of most geologically studied areas in the African region, but then the country underwent a period of political instability resulting in mineral exploration being put on the back burner. It wasn't until 1993 that the political instability vanished when the country returned to a liberal democratic form of government. It wasn't until recently however, that it began to regain some of the lost footing it once had in exploration and mining.

Although Madagascar is considered to be a part of the African Continent the island geologically is a micro-continent between Southern Africa and India. This becomes readily apparent when you start looking at the local geology and the flora and fauna. The geology of the island is more akin to that of Sri Lanka and India that is anything found in Africa.

Madagascar's primary gold deposits are similar to those of the Abitibi region of Canada than anything else. Like the Abitibi the gold is associated with greenstone belts, quartz reefs and veins, and is also found the fuse for the country rock in deposits similar to those of the Carlin Trend in Nevada.  There is a great deal of gold that is also associated with that volcanogenic massive sulfide (VMS) deposits similar to those that are found at the kidd Creek Mine in Timmins, Ontario or the Horne Mine in Rouyn-Noranda, Québec. Both of these mines are in the Abitibi Gold Belt of Canada.

Gold isn't the only thing found in Madagascar that is worth money.
Photo by Rob Lavinsky

Alluvial gold is also been recovered from both ancient and recent placer deposits as well as lateritic earth. Aside from the gold deposits found in Madagascar is also the home of many valuable gemstones including those of the ruby and sapphire family that are mined mainly by artisanal miners although in some cases a few of these mines have been mechanized.

Although the primary gold deposits found on the island predate the breakup of Gondwana one of the two continents that made up the supercontinent Pangaea. This is very important to remember because it makes the regional tectonics arrival into the emplacement of gold deposits. Madagascar's gold bearing rocks are all part of its suite of basement rocks. These rocks are divided into three different systems with the youngest being the Vohibory System, the middle is the Graphite System and the oldest is the Androyen System. Most of the gold however is found in the graphite system. There are also some interesting gold deposits in the Vohibory System.

How the Wild Lands Policy Affects the Gold Mining Community

Bishop Lauds Proposal to Defund DOI Wild Lands Policy
WASHINGTON— As nationwide opposition to the U.S. Department of Interior's (DOI) Wild Lands policy continues to grow, Congressman Rob Bishop (R-UT) today praised the House Appropriations Committee for including a provision within the House Continuing Resolution (CR) that would cease all funding for Secretarial Order 3310, the DOI's hasty new "Wild Lands" proposal which seeks to unilaterally designate what amounts to "de facto" wilderness areas on BLM lands.  Bishop serves as Chairman of the House Natural Resources Subcommittee on National Parks, Forests and Public Lands and remains a stalwart advocate in Congress forpublic land users and communities and has helped lead efforts to reverse the Wild Lands policy since it was announced. 
"Cutting funding for the Wild Lands policy is an important first step as we seek to stop this Administration from tightening its heavy-handed bureaucratic stranglehold on public land communities and users across this country.  I thank Congressman Mike Simpson (R-ID) for taking the lead on this provision and I look forward to fighting the Wild Lands policy all the way to its ultimate extinction," said Congressman Bishop. 
Under the DOI's new Wild Lands policy, more than 220 million acres of unclassified multiple use lands would be subject to further review to determine whether or not they can be classified as "Wild Lands."  If the lands are determined to be eligible for the new classification, they would then be subject to new land managementregulations that restrict multiple use and access.
 "It should come as no surprise to Secretary Salazar that communities and stakeholders across the country, especially in the West, are outraged by this new proposal.  The DOI unilaterally moved forward in announcing the policy without the participation or buy-in from local officials, communities, industries and stakeholders who would be affected by new Wild Lands designation.  You can't blame them.  They were left in the dark and what you are seeing in Congress is a direct result of the frustration that so many feel about the manner in which this policy came about.  Poor process always produces poor product," Bishop stated.
 *The specific provision regarding funding of Secretarial Order No. 3310 can be found in section 1778 of theHouse CR.

Thursday, February 10, 2011

Gold Occurrences in Germany

The history of gold mining in Germany goes back to Neolithic times long before the Romans with the discovery of many gold artifacts dating back to that time. Although gold mining pre-dates the Roman Empire the first serious mining for gold in Germany was done by the Roman miners. The problem is identifying the places where gold was by in prehistoric times. From the discovery of objects made from gold it becomes quite obvious that during the second phase of mining in the Middle Ages was the time when much of the gold in Germany was produced.

The area around Neusschwanstein Castle may be gold bearing.

It was during the same period that the first book on mining was published by Georgius Agricola (Georg Bauer), “Re de Metallica” that laid the foundation for the modern study of mining engineering, and still finds use as a historical reference book. It was during this period that Nuremburg rose to prominence as a mining and smelting center.

The discovery of the New World by Columbus in 1492 saturated the European market with gold so that the search for gold in Germany or Europe languished from that day on. Most of the Golden Germany is found in volcanic and metamorphic rocks of pre-Cambrian age. Other sources of gold in Germany can be placer deposits in the stream gravels of various streams and rivers. They are also found in what are considered fossilized gravel deposits of Paleozoic age especially in the foreland north of the Alps.

The Crown of Bavaria that could be made from German gold.

Another area of interest is the Mesozoic aged kupferschiefer deposits that occur in sandstone in veins up to a meter thick where the gold occurs as a byproduct of the copper sulfides found in these deposits. In this case the gold often occurs as a thin film between the crystals of the sulfide minerals.

Most of the evidence for gold comes from the discovery of pre-Colombian artifacts that are discovered during archaeological digs. At this point it appears that the number of gold deposits as large, but gold itself is sparse. There is a pretty good chance that more gold deposits may be discovered by a program of exploration using modern equipment and methods.

Wednesday, February 9, 2011

Gold Occurrences in New Jersey

The first mention of gold in New Jersey dates back to 1829 when gold was reported from the general area around Franklin. The report failed to mention whether this was lode or placer gold, but from the geological history of that area it could have been either. One of the features in New Jersey shares in common with all the other states of the northeastern United States is the possibility of placer gold being brought down from the Abitibi Gold Belt in Canada.
An adit in the Sterling Hill Museum at Sterling Hill, NJ

Gold has been reported in the ancient rocks of Grenvellian age from Sussex County associated with the iron deposits.  It has also been reported from the Schwangunk conglomerate from extreme western Sussex County in the vicinity of High Point, New Jersey.  The stone here is a conglomerate composed of quartz pebbles that is identical to the conglomerates of the Schwangunk Mountains of New York State.

Sussex County is also the home to some very rich zinc deposits at Franklin and Sterling Hill.  Although no gold was apparently found at these localities gold is often associated with zinc as a byproduct of the smelting process.  These zinc ores are contained in Precambrian marble with iron and manganese ores at times creating minerals containing both iron, manganese and zinc.  There have even been reports of corundum crystals being found in the same marble.

There have been reports of so-called gold mines in the past one notable example was in the Schuler Mine that showed some gold in quartz.  Many of the reported gold mines in Bergin County during the 19th century were actually scams. 

Southern New Jersey is covered with outwash composed of sand & gravel from the last glacier that came as far south as Staten Island where terminal moraines can be observed half way down the island.  There is a possibility that a small amount of gold may be present in the gravel topping the hills of Ocean County that was brought down from Canada by the glacier..

Although gold appears to be sparse in New Jersey there is otherwise a very rich history of mining for several other commodities including copper and silver in the Newark Basin basalts and sandstone. In the mid-19th century there were several mines producing copper and byproduct silver in this area of New Jersey

Tuesday, February 8, 2011

Gold occurrences in Finland

The adit of a mine in Finland

One of the last places in the world you would expect gold is Finland, but it does have a very diverse geological history that has led to the creation of many different types of gold deposits of a variety of ages and different styles of mineralization. In the past any gold produced in Finland occurred as a byproduct from the mining of various Volcanogenic Massive Sulfides (VMS). It is only within the past decade that this situation has changed because of the closure of some of the baseball to mines, and the beginning of production from some of the recently discovered gold only deposits.

The gold deposits occurred during several distinct episodes of the crustal evolution of Finland. Gold deposits began in Finland during the Archean word forms and greenstone belts with low-grade copper, cobalt and nickel massive sulfides were formed. The same geologic setting created low grade ranging from 0.1 to1.0 ppm of gold but it is in very large deposits. Another type of gold deposit is found in the Tampere schist belt in southern Finland that is host to the Kutemajarvi gold deposits that in the period ranging from 1994 to 2003 produced 13 tons of gold from 1.4 million tons of ore. This mine was reopened in June 2007 by Dragon Mining that now operates under the name of “Orivesi Mine.”

The gold deposits in Finland are mainly associated with the Baltic Shield, but in the northern part of the country they are found in the greenstone belts of central Lapland where there are very few deposits having atypical mineralization.  Many of these deposits contain a significant enrichment of copper, cobalt, nickel and in some deposits uranium.  The areas having the largest potential for gold are to be found in the Paleoproterozoic greenstone belt located in eastern Finland and Lapland.  In the western Central Lapland greenstone belt there is the possibility of finding iron oxide, copper and gold deposits.  These systems are found in the western part of the Central Lapland greenstone belt.

In Central Lapland the greenstone belt is found in the northern part of the Fennoscandian Shield.  The mineral deposits found in this area are mainly sulfides and sulfoansenides in nature that also have gold values.  In this they resemble BHP Billiton’s deposits at Olympic Dam Mine located in Australia.

Sunday, February 6, 2011

Flame Tests

Flame tests may not be the most accurate, nor do they work for gold, but they can be really effective for other elements.  Boron is one that imparts a greenish color to a flame.  This gives rise to the story of how the 20 Mule Team Borax Company got started.  It seems a prospector who was down on his luck was prospecting Death Valley, California with his wife when he tried a flame test on some of the dried salts he found in the dessert.  It burned green so he turned to his wife and said, “She burns green Ma, we’re rich!”

A chemist performing a flame test on copper sulfate.  Notice the blue color of the flame.

Flame tests are conducted on a length of thin platinum wire that is first dipped in a dilute solution of hydrochloric acid then in the pulverized sample of the substance to be tested; then it is held into a hot flame.

Depending on the element contained in the sample it colors the flame various colors.  This technique will present a pretty accurate idea of what king of substance you have, but the accuracy of the test can be improves with a spectroscope.

Table 1 shows the colors of the flame test of various elements:

Pale/Apple green
Brick red
Copper(II) (non-halide)
Copper(II) (halide)
Mn (II)
Manganese (II)
No colour
Pale green
Pale green
Pure green
Bluish green