Gold!!

In 1558 gold was discovered in the headwaters of the Tambopata River, near what is now the town of San Juan del Oro in Puno. Gold was subsequently discovered in neighbouring rivers such as the Inambari, and gold fever quickly spread down these rivers to the Madre de Dios.

In Madre de Dios most gold is found as alluvial deposits in existing and old river courses. Today it is extracted manually with the use of small water pumps or on a larger scale using motorized floating dredges, bulldozers and cranes, though all current methods rely on mercury in the separation process (see diagram).

Gold extraction in Madre de Dios boomed in the mid-1970s, due to the increase in the price of gold worldwide. Today some ten thousand people work in the gold industry, the majority of them young male migrants from the Andes who arrive during the dry season when river levels are low and conditions optimum.

On average, twenty metric tons of gold are extracted each year in Madre de Dios and reserves are estimated at 1,000 tons, though only a fraction of this total is readily accessible.

Ecological effects of gold mining
The use of floating dredgers not only results in the destruction of river banks but also significantly increases the silt load of the rivers, which could be doing untold damage to fish populations.
In areas where the forest has reclaimed old river channels and at ox-box lakes rich in alluvial gold, large scale deforestation is taking place and the top layers of soil are being stripped away. The result is a red desert, where the earth has been so badly affected that no seedling is able to grow.
Each year in Madre de Dios, approximately 40 metric tons of mercury is used in the extraction process. An untold quantity escapes into the soil and waterways of the forest and more is vaporized during the purification process and falls as mercury-laden rain over neighbouring areas. Mercury survives for very long periods in the environment and can readily enter the food chain, slowly poisoning many organisms, especially carnivores high in the food chain such as giant otters, jaguars, and human beings.


THE GOLD EXTRACTION METHOD PRACTICED ON THE MALINOWSKI RIVER.
1. A group of 6 people manage the floating barges, known locally as "dragas", of which there are 40 on the Malinowski River. A large diesel powered pump and compressor are used in conjunction with a diver to suck the river sediments onto the barge. The sediments are made to run across a series of carpets covered in small bristles. These trap fine sediment particles including gold. On average, work continues on the barges 18 hours a day.

2. After a period of 9 hours or so the pump is turned off and the carpets are placed into large 50 gallon drums for washing. After the carpets have been washed of their sediment load the suspension in the drum is allowed to settle and the excess water is siphoned off.

3. To the thick sediment deposit in the base of the drum is added liquid mercury. This metal binds well with gold and an amalgam is quickly formed which, because it is heavy, sinks to the bottom of the drum.

4. The mercury and sediment are thoroughly stirred to ensure all the gold comes into contact with the mercury.

5. Portions of the sediment/amalgam are transferred to a smaller container. Water is added and with a sloshing motion the excess sediment is extracted, leaving a thick heavy residue of gold/mercury amalgam.

6. The residue is transferred to a large piece of cloth and twisted. Excess liquid mercury escapes and can be reused.

7. The residue is then transferred to a heat resistant plate which is heated thoroughly from below and above. Mercury has a significantly lower boiling point than gold and all the mercury is vaporized along with any impurities in the gold itself. After several minutes the only substance left is 24 carat gold.

Most of the gold is sold to middle men in Puerto Maldonado or Cusco for approximately 85% of the world market price.