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Ancient alluvial gold mining in Goa

Nandkumar M Kamat

 

Since all the 11 local rivers, their 41 tributaries and the 600 plus streams that drain into (for millions of years now) flow over Archean rocks of the highly metallogenic Western Dharwar Craton that contains various amounts of gold, it is obvious that the sand forming due to continuous rock weathering and erosion and which accumulates in the lower parts where the current slows down contains gold, either as secondary grains or combined with silica known as auriferous quartz.

The Directorate of Mines and Geology knows next to nothing about Goa’s ancient metallurgical traditions and especially the importance ancient communities gave to gold panning from river sands – a process known universally as artisanal alluvial gold mining. It was a serious or perhaps a deliberate blunder on the part of the Government of Goa not to mandatorily subject pooled samples of alluvial sands of rivers to detailed mineralogical and geochemical analysis to identify number and morphology of pure secondary gold grains or auriferous or gold containing minerals before listing the sites where sand mining would be permitted.

Such a decision would drain the state of valuable gold resources due to the mental block the Government has with regards to simple geochemical and mineralogical analysis, a process which takes just a week of laboratory work. It appears that the Government may know the fact and may be deliberately permitting clandestine diversion of gold-containing sand deposits in the name of sand mining for the construction industry. Some sites where gold particles and gold containing minerals are known to be found  include all the four sand mining sites identified by government in Dharbandora, three in Sanguem and two in Quepem besides  Amona in Mandovi, Camurlim and Colvale in Colvale River, Keri and Ugvem in Tiracol , which are sites rich in alluvial secondary gold.

We detected very high concentration of pure gold particles and gold containing minerals in the Colvale river sand, which is famous for its quality in the construction industry. But, 1600 years ago the Buddhist monks, who had knowledge of alchemy and metallurgy, already knew the importance of gold in the Colvale river sand. Professor, Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur, R K Dube, has written a wonderful paper ‘Alluvial Placer Gold Mining in India through Ages: A Historical Perspective’.

He writes: “The Pali text Aguttara Nikāya (3.10.10) in its Pansudhovaka Sutta has narrated the process of the recovery of gold dust or particles from alluvial placer gold deposits. The description of this process was used beautifully as an allegory in explaining the removal of various evil thoughts from the mind in order to retain only the thought related to Dharma (i.e. religious or moral virtue).”

According to another scholar Pande the dates of the composition of the Nikāyas fall between the 5th and 3rd centuries BC. The gangue present in the alluvial placer gold deposit was a mixture of coarse, medium and fine size material. A series of successive panning processes were used to remove these materials in steps starting with coarse size material first, followed by medium and fine size materials. The reference stated the fine size gangue also contained black coloured fine particles. In all probability these could have been magnetite. The mining of the auriferous sand and gravel, and the subsequent recovery of gold from it was carried out by the same person.

The ancient Sanskrit word for the alluvial placer gold miner-cum-gold washer is “pānsudhāvaka”. The literal meaning of the term is “the one who cleans or washes sands”. It is no wonder that the Buddhist who named Goa and the surrounding Konkan region as “Golden Aparant” had set up riverside camps to exploit alluvial gold resources. One such camp existed in a ward of the Colvale village, known as “Mushir”. There is reference to a Buddhist shrine in Colvale in the AD 1647 Portuguese document ‘Tambo das Rendas de Salcete e Bardez’.

When Jesuit historian  Fr Henry Heras was surveying this area in 1930 on basis of local information he discovered a stone sculpture of Buddha which he dated to AD 400. Examination of the sculpture indicates that the Buddhist colony was significantly large and was definitely sustaining itself by mining readily available alluvial gold. Magnetite is dominant in sands of Colvale so the references indicated in Aguttara Nikaya match the composition and quality of gold containing sands of Colvale.

The process of separating gold particles from lighter fraction of the sand also matches the process followed at Mushir, Colvale. After removal of organic silty fraction, Colvale sand becomes enriched in auriferous material. Buddhist pānsudhāvaka then used the principle of high density of pure gold particles in serial washing to remove the lighter sandy fraction and capture the heavy gold grains. Such processes are universally followed even today in many countries as can be seen from educational videos available on this very useful website http://www.wheregoldis.com/.

 

(To be continued).

 

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