Mineral
Specimen Collecting (Technical Note: The blue underlined hyperlinks in this article are either linked to technical information, or to Google image links, e.g. click below on Pancho Villa for a variety of images of the legendary PV, then select and click any image for further info, or click on Tequila to find out the truth about the gusano worm in the bottle........) Introduction For the last 20 years, the author has been visiting mines, mineral fairs, and mineral dealers to purchase and self collect minerals from over 40 countries to date. One of his guiding inspirations was Peter Bancroft’s excellent book Gem and Crystal Treasures which describes Bancroft’s selection of the 100 localities for the world's best mineral specimens. This essay will describe some of the background and history of famous localities, and the minerals found there. It is anticipated that those readers interested in the Precious Metals, Gold and Silver, and the PM share market, may find interest in these anecdotal tales of mines and minerals, and enjoy the beauty of one of nature’s hidden treasures; --- mineral specimens. --- Note: Gold and Silver are metallic elements. They are also minerals when they occur in pure form in nature, and are then described as native gold and native silver. There are just over 4000 mineral species discovered world wide to date. Incidentally, new minerals are still being discovered today thanks to the advance of science in laboratory analytical techniques, rather than new mining or exploration technology. Minerals tend to be named after localities, new specimen discoverers, famous geologists, mineralogists, or collectors. Take for example Morganite, the Beryl variety coloured pink by traces of manganese. In the year 1911 New York gemstone expert G.F. Kunz suggested to give Pink Beryl the status and standing of an individual kind of gemstone, and it was named in honour of banker and minerals collector John Pierpont Morgan, thus receiving its current name: Morganite. Mexico Silver Sulphides - Acanthite, Stephanite, and the attractive, rare, and sought after, ruby silvers Polybasite, Pyrargyrite. In 1998 the author spent 2 months touring the silver mines in the north of Mexico with the late Walt Bowser as guide. We drove down through Chihuahua, Fresnillo, Durango, Mapimi, Zacatecas, Guanajuato as far south as Taxco, (large market for silver artifacts), and then back to Texas. This is desert country, and all that changes on the road south are the types of cactus, from Yucca to the Joshua tree, with other types remaining ubiquitous like the prickly pear, attractive when in flower. The Agave plant is the base for the notorious Tequila. It is also Pancho Villa country, a controversial revolutionary, folks hero or bandit, who robbed the silver trains from the mines on occasion in the early 20th century. “Senor Walt” was also received in the mining villages as a hero during our visits, because he distributed second hand clothes, shoes, and other items to the poor mining families, meanwhile filling up his trailer with the mineral specimens we bought from the miners. In Zacatecas we descended the mineshaft to the 100 level at the Veta Grande mine. Here Walt tells the full story of a 1997 tour for those interested in all the mineral details, courtesy of the Canadian RockHound web site. Very sadly Walt passed away in 2003, but he was such a legendary charismatic character that 20 or so of his friends and family including myself got together by email and wrote tributes to him. The results were collated and published in a special commemorative pamphlet edition of Rockhound Notes in June 2003. This was a most moving experience and a novel spontaneous expression of Cyber-grief.
Native silver specimens are also occasionally found at some of the mines, such as at Batopilas, and the silver is usually in complex forms often described as and resembling wire.
The houses that once housed 2000 miners (click here and compare with my photo in 1998!!) are now ruins, and the mine deserted apart from a few visitors like myself.
Mexican Opal .At Queretaro, the author visited a fire opal mine and after purchasing a mine run lot, was invited by the owner to self collect some material in the “open pit” mine. Specimen Mining Commercial mines target production volumes, and any extraction of mineral specimens has to be carefully managed to avoid disruption to mining schedules. However a new type of mining solely for mineral specimens for sale to collectors and museums has emerged over the last decade or so. Bryan Lees of Collectors Edge has pioneered new techniques for working disused commercial mines, or other mineral localities to extract mineral specimens undamaged by the mining processes. His most noted success has been at the Sweet Home mine, Alma Colorado, which the author visited in 1995. The Sweet Home was originally a silver mine, but is now famous for the world’s best Rhodochrosite specimens. Gold Gold is a noble and versatile metal as seen by its properties. It is also rare, gold (Au) is only 0.002 parts per million of the earths crust, compared to iron (Fe) which is 62,200 ppm. Note that gold is more rare by a factor of 40 than silver (Ag) whose abundance is 0.08 ppm. However gold specimens are even more rare. This is because in the majority of gold mines, the gold is not visible to the naked eye, but finely dispersed in the matrix, which may consist of quartz, sulphides, or other host rocks. Note how gold specimens here from different mines have subtle differences in appearances, occasionally allowing identification of the source mine. Gold was featured at this years Tucson Mineral Show 2004, the world’s largest mineral fair held annually at Tucson, Arizona. Scroll down here courtesy of Trinity Mineral for some more wonderful photos of gold in various shapes, forms, and sizes, including some world-class specimens from localities described below. Eagles Nest mine, California: Some of the most attractive native gold specimens in fine crystallised form have come from this mine, and have been marketed by Wayne Leicht. Currently this specimen mine operation has started up again and it is hoped good material will soon be on the market again in reasonable quantity.
Breckenridge, Colorado was settled in 1859 as a gold and silver mining town. A collection of the distinctive gold specimens mined over the years can now be seen at the Denver museum, including Tom’s Baby, an eight-pound nugget of crystallized gold unearthed in Breckenridge in 1887. Gold specimens in nugget form are also collector’s favourites, and are often found in alluvial gold fields using metal detectors. Gold, as a noble metal, is relatively chemically inactive. However it does occur rarely in nature in the form of minerals, combined with other elements such as silver, copper, tellurium, lead, and antinomy. Cripple Creek, Colorado is another famous gold mining district, where gold was found in the form of Tellurides. Here the author went on an underground tour at the Mollie Kathleen gold mine. Exploration and discovery of gold in the 19th century was a chance affair and usually relied on finding visual gold, either in matrix in an outcrop, or in nugget form, or by gold panning in streams and rivers. Any rich discovery was often followed by a gold rush. South Africa: The first gold rush started at Pilgrims Rest, which was declared a gold field in 1873; soon after digger Alec "Wheelbarrow" Patterson had found gold deposits in Pilgrim's Creek. The Valley proved to be rich in gold and by the end of the year, there where about 1500 diggers working in the area, living in tents in squalid conditions. (His nickname arose from the fact that he arrived at Pilgrims Creek with all his worldly possessions carried in a wheelbarrow.) President Burgers, on hearing of the gold strike, hastily had the Transvaal Mining Laws drafted, (none having existed until then), after a quick study of the Mining Laws of Australia, New Zealand, and California. He then visited the mining camp with some aides, and after some negotiations with the miners and amendments, the new laws were put into place.
In 2001 the author panned gold during a visit to Pilgrims Rest, and was delighted to see a few tiny flakes at the bottom of the pan, nestling with some other black heavy minerals. This photo shows the author inspecting some antique mining equipment at Pilgrims Rest. South Africa still claims to be the largest gold producer, with ca 40% of the worlds known reserves, and some of the richest and deepest gold mines. North America has experienced many gold rushes, including California from 1848 to 1864, and the Klondike in 1896 but at Nome the gold was literally found on the beach. “The coast was icebound for the season, but gold seekers began descending on the tent town in the spring of 1899. During that summer alone, more than two million dollars' worth of gold was taken from the beaches of the booming city of Nome.” It is interesting to note that, despite the short duration of these historical gold rushes, several new gold mines are planned to open in Alaska and British Columbia over the next few years. Despite the large quantities of gold mined during these gold rushes, few specimens from that era remain. In fact the majority of gold specimens in collections today, have been mined in the last 25 years, either in specimen mines, or commercial mines with a policy of saving mineral specimens, and in smaller quantities from amateur gold panning and metal detecting. It is to be hoped that new gold specimens for the collectors market will become available from some of these new mining projects. This essay makes no attempt to cover all the best localities, (historically or more recent), for gold specimens, but for those interested in an in-depth coverage Robert B. Cook’s article in Rocks &Minerals Jan/Feb 2004 is highly recommended. (See link in Further Reading below.) Gold exploration has changed radically from those bygone days. Geophysical and geochemical surveys are now used to identify drill targets. Drill programs are used to create Feasibility Studies, followed by permitting, construction and production, normally a 7 year process. The cost of building a new large gold mine runs into several hundred million us$. The days of the Gold Rushes have gone, but Gold fever is now still occasionally seen on the stock markets, when gold drilling results are reported by a mining or exploration company! One famous mine currently producing gold specimens for collectors is the Red lake mine. David Joyce sells the specimens on behalf of Goldcorp, and kindly agreed for his essay to be reproduced here (an abridged version of the original which appeared in Rocks and Minerals). |
Access
in those days was via Mozambique crossing
what is now the Kruger Park.
A visit to the cemetery testifies to the low life expectation of
the miners. Many, who escaped the dangers of lions and other predators
succumbed to malaria or other tropical diseases.