Total Pageviews

Showing posts with label hard-rock. Show all posts
Showing posts with label hard-rock. Show all posts

Wednesday, May 16, 2012

Gold Occurrences in the Argentine


Map of Argentina.  The provinces in the far west of the country are most apt to contain gold
By Bliff


Although an ocean separates them Argentina has a neighbor the country of South Africa that although they were split apart with the opening of the Atlantic Ocean during the Cretaceous millions of years ago they share much in common.  Forty percent of all the gold that has ever been mined comes from the Witwatersrand in South Africa that leaves the question are like gold deposits to be found in the rocks of Argentina.  The very name of the country is derived from the Latin word for silver “argent” hence Argentina.

Argentina overhauled its protectionist mining laws in 1993 causing gold production to rise in a parabolic curve from a mere 36,000 ounces to over 1 million ounces.  This change in the laws has made Argentina the third largest producer of gold in South America.  This number was only exceeded by Peru and Brazil, respectively.  Only Argentina has seen as dramatic a rise in recent years.

Only in Argentina has the level of gold production raised in recent years with the production of gold having peaked in the other countries.  These points out the fact that unlike the others Argentina’s gold fields are from being mature is respect to their development cycles.  Argentina’s wealth of buried gold is yet to see any meaningful development translating into a booming domestic gold industry with a pronounced growth curve.

In area Argentina is the second largest country in South America that is 1,580 kilometers from east to west and 3,460 kilometers from north to south.  To its west it borders Chile along the crest of the Andes.  The country has well over thirty volcanoes that also follow the Andes which have supplied the heat engines necessary to forming deposits of gold dissolved in their hydrothermal waters.

The presence of placer gold in the rivers and streams draining the eastern slopes of the Andes Mountains are known to contain large amounts of placer gold.  Some of the deposits that have been found are supposed to exceed 1 million ounces of gold.  Some of this gold is pristine crystals giving weight that gold nuggets are caused by gold fixing bacteria.  Much of this crystalline gold is as high in content as >98% pure gold, some of the purest in the world.

Lode gold is often associated with arsenopyrite and copper sulfides the normal byproducts of hard-rock gold.  Another element often associated with the gold from Argentina is mercury that may explain why the placer gold has such a high percentage of gold because the mercury left over from past mining operations has dissolved the residual silver.  There are lode deposits the length of Argentina in the spine of the Andes Mountains.

Tuesday, May 15, 2012

Gold Occurrences in Bolivia


A scene from Potosi a famous Bolivian mining center.  Note the volcano in the background a source of gold deposits.
Photo by Idobi


Although Bolivia is noted for its tin production especially in the area around Potosi gold mining and prospecting proceeded at a brisk rate during the late 1980s.  Gold is found throughout the country with more then 300 cooperatives and over 10,000 prospectors producing gold.

Bolivia like many other countries in the world now faces a trade-off between economic growth vs. the environment.  The country derives much of its foreign exchange from the mining industry with zinc being its largest mining export followed by tin, gold and silver. As a result of this dilemma Bolivian mining companies have developed tighter rules with gold mining being an important source of foreign exchange for the country.  Things get difficult because Bolivian and U.S. environmental groups continue to fight prospecting and mining efforts because of their devastating effects on the local environment.

The practices of the mining industry leads to soil erosion combined with pollution of the country’s fresh-water resources.  This leaves the peons of the country torn between mining and jobs or protecting the environment that fails to bring Bolivia much needed jobs.

Mining is the mainstay of Bolivia’s economy with around 50% of its foreign exchange coming from this source.  The country’s private mining sector has continued to grow led by Canadian and U.S. companies.  The government has set aside a large area about 120 km north of LaPaz for gold mining and exploration.

There are plenty of active and extinct volcanoes in Bolivia to provide heat engines to drive the hydrothermal waters responsible for building gold deposits when the water reaches conditions that will precipitate the dissolved gold from solution.  This volcanic activity has given birth to extensive deposits of hard rock gold and abundant placer deposits in the country’s rivers and streams.  There is both artisanal and full scale mining in Bolivia, and it’s still ongoing.

Mining has been going on in Bolivia since the days of the Spanish conquest that began in 1524 and was mainly completed in 1833.  In those days after the conquest what is now Bolivia was known as “Upper Peru.”  When it was founded in 1545 as a mining center Potasi quickly started pouring immense mineral wealth into the coffers of the Spanish Empire it quickly became the largest city in the New World with a population larger then 150,000.  The Spaniards were mainly interested in gold it was later that Potasi became known for its tin deposits.  Mineral wealth continues to pour from Bolivia. .