Lecture: Fossil & Mineral Collecting in Bolivia

by

Bob Maurer

Notes by: R Coleman

Bob breezed into his talk by stating a few basic facts about Bolivia and the mineral belt running parallel to the Andes. These were the result of the Nasca Plate subduction (Pacific Ocean) beneath the less dense continental crust of South America causing the uplift. The mineral belt was stated to be primarily hydrothermal thermal vein deposits arising from heat generated by the subduction event and the percolation of ground water.

Bob is quite a character and when the opportunity arose to go collecting in Bolivia he jumped at the chance and teamed up with a German geologist. What first surprised him was that the native population had so many physical features similar to the peoples of Mongolia. He mused over the possible migration of these people in earlier times. Although Bolivia has considerable mineral deposits, it is a poor country, landlocked and politically deadlocked in dispute with Chile over old wars and territorial disputes. Hence with no ready access to the sea there is no possibility of capitalizing on this buried wealth for the benefit of the country. Other resources around the World have less overheads!

Bob's collecting style was quite interesting. He said that because of the high terrain effective radio coverage of the whole country was difficulty, so each town had it's own local radio station. They would arrive in town, advertise over the local radio that they were buying mineral specimens and set up a table. He said it was sad that many specimens were damaged because the people hadn't got a clue about wrapping them up. They would arrive with a bag full and many specimens would get damaged in transit. Occasionally when something of note arrived, they would ask the finder where it came from and give them a few dollars to take them to the spot.

Bob said that the terrain was at an elevation of between 2 to 3 miles and that luckily he did not suffer any effects from altitude sickness. He showed us pictures of hydrothermal veins outcropping at the surface from where he collected and a few pictures of the mines they visited. Notable, at a cassiterite mine site, was the way the locals were crushing ore with a massive semicircular concrete roller. They just rocked back and forth. It truly looked medieval in style. Bob said that it was similar to the way people worked in those early times. Many of, if not all, the mining practise would be illegal in the western world. In Bolivia people were used in preference to machines. Life expectancy in the mining industry was short, but this was offset by a high birthrate.

A miners typical sustenance for the day was a bag of coca leaves which they chewed in a ball kept on one side of mouth and another ball of kaolin on the other. (Hamsters spring to mind) Bob covered the various ways coca leaves were put to use and crudely refined by the locals. One was a herbal tea with wonderful curative properties! (I wonder what he packed his minerals in?)

Bob showed some pictures of rivers totally polluted by Zinc effluent through mining and he was (as we all are) disgusted by the ecological damage this is doing. He showed a slide of the settling tanks and recycling system he used when mining in Australia, a relative simple system and effective solution.

(For me, this may have been a oversimplification of the problem. Bob's mining technique in Australia may have been in a more arid climate were conservation of water is paramount. These rivers in Bolivia could have been polluted by attempts to drain water from mine workings that would otherwise flood and not part of ore processing. Considering the vast amounts of water that may be involved, settling pools/lakes and filter systems would be beyond an economic proposition for these poor people, or so they would think! Mine effluent is a major problem and must be dealt with effectively to avoid an ecological nightmare now, or in the future. The answer is, if it can't be controlled, then don't mine. Easy said, impossible to implement. )

On one of his mineral trips, Bob first visited the local general store to buy his dynamite, detonators, and cord!

Up somewhere high there were fumarole holes with sulphur forming around the vents. Locals, oblivious to the damage all these gases were doing, earned a living by collecting the sulphur crystals. It may have been a living but only suitable for a short life! Bob gave us the lowdown on how to dynamite the sulphur without blasting the crystals to bits. One piece of information was not to crimp the wrong end of the detonator when fitting the fuse. Another tip was to walk at a steady pace away from the dynamite after lighting the fuse, as if you run you may fall over and never get up again! Bob was so upset by the working conditions these people suffer, he no longer trades in sulphur, but he said he loosened up as much as a could for them before he left! Also recovery and refining the sulphur has ceased (dwindled ?). The World's sulphur supply is now extracted from crude oil as a by-product of the refining industry and requirements for cleaner fuels.

Two or so miles high Bob came across outcrops of a stromatalite reef complex. He had brought along a large polished section (slightly dished reflection, says a lapidary) for us to view. Bob briefly described acetate peels for those interested in a closer look at the petrology and pointed out some of the more finer detail. He also showed a few slides of his fish fossils he found in a horizon beneath the stromatalites. These specimens have yet to be identified. A question that remains unanswered is; "what is the age of the stromatalite complex"?.

Our speaker covered a lot of ground in his talk, and backed this with a prodigious display of Bolivian minerals and fossils he had collected. The display stretched for some 5m along one side of the hall. There were some rare and classic exhibits to view. (I've seen pyrite before but never a bed of octahedra or a large single octahedron outside of picture book. The other minerals specimens were astonishing!) Sorry no pictures if you were expecting some, I couldn't have done them justice. Anyhow why weren't you there to see for yourself?

RC 23/5/2002

Announcements:

The Society is currently preparing an exhibition/display to the general public at the Dagenham Town Show in July and Alan Smart will be coordinating the display. Our chairman appealed to members for the loan of specimens for the show weekend. Two further displays are being planned for early November for which assistance will be required. If any member can help please contact: Graham Ward, coordinator for the GA Reunion (2 November) and Les Lanham for the Kempton Park Show (2 & 3 November).

Field Visit to Isle of Sheppey: David Turner said that 22 members attended the trip, on this occasion there were more fossil seeds to be found than usual, whilst other fossils remained elusive. David found a Nautilus which he had on display at the meeting. Another member, Bob Blackburn brought along his finds for the trip. For a more detailed and report and pictures see Isle of Sheppey