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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 worlds 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 artefacts), 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.
A highlight of the tour was the visit to the famous cave of swords with its massive gypsum crystals up
to 2 metres in length seen here with a photo of the author.
Some photos of Mexico mineral specimens from mineral dealers can be
seen at the following web sites; http://mineral.galleries.com/minerals/fablocal/mexico.htmJohnBetts, Arkenstone
selection, and http://www.davebunkminerals.com/ag/silver2.htm
with the latter showing 3 pages of the above-mentioned silver sulphides from
the mines in the areas visited by the author.
 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.
Some of the silver mines in Mexico have been operating for over 400
years, and are so rich in silver ore that it is estimated that up to one
third of all the silver ever mined in history came from this region. Compare
this to average mine lives worldwide usually measured in years or decades,
not centuries. Silver is normally mined as a by-product in lead/zinc mines,
but in Mexico the ore often consists of a high grade mixture of the silver
sulphides described above.
 The famous Roebling suspension bridge, 325 metres long, crosses a deep canyon at the Ojuela mine near Mapimi, and remains as a landmark at a
mine that still delivers rare and world-class specimens, including Legrandite,
and has produced some of the worlds best Adamite
specimens. The bridge, the second longest suspension bridge in the world when
constructed in 1899, connected the mine with the new town and railway. Penoles
operated the mine from 1893 until its closure in 1946. "Thousands of
Penoles miners and a million Tonnes of high grade silver ore passed over the
bridge," (Bancroft).
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.
 Crystalline native gold on quartz matrix. Eagles
Nest Mine, California, USA. 8 x 7 cm. Museum of Geology, Lausanne, Switzerland. Photo Stefan Ansermet.
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 19 th 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 were 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.
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.
 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).
The Red Lake Mine: The Richest Gold Mine
in the World
David K. Joyce
Box 95551, Newmarket, Ontario
Canada L3Y 8J8
dkjoyce@attcanada.ca
Stephen McGibbon
Manager Exploration, Goldcorp Inc.
Balmertown, Ontario, CanadaP0V 1C0
smcgibbon@goldcorp.com
Introduction
 In 1989, Goldcorp Inc. took over Dickenson Mines
Ltd, a venerable gold mining company that, since 1948, had operated the
Arthur White mine in the Red Lake mining camp, located north of Lake
Superior, near the Ontario Manitoba border. Robert McEwen, chairman of
Goldcorp Inc felt that the adage, "the best place to look for a new
orebody is near an old mine" had some credence. Was he right!!? Goldcorp
initiated an exploration program while the old mine rolled along as a
break-even or money losing gold mining operation. During early 1995 while
testing Goldcorp's geological theory, diamond drillers cut across a very
high-grade body of mineralization that was soon to become the fabulous
"High-Grade Zone (HGZ)". Diamond drilling continued and the HGZ has
proven (at time of writing) to contain more than 1.96 million tons of
high-grade ore containing 4.6 million ounces of gold. That is an average
grade of 2.35 troy ounces per ton! Most gold mines in the world average well
under 0.5 troy ounces per ton. So prolific was the change in fortunes of the
mine, that the Arthur White mine was re-named the Red Lake mine.
There are other orebodies in the world that, being larger contain
more troy ounces of gold. However, to our knowledge, there are no other gold
mines that contain the average grade of ore that the Red Lake Mine
does. These sorts of orebodies come along only once every several decades, or
so.
The HGZ changed the economics of the old mine so much that Goldcorp
Inc. decided to build a brand new mine around the new orebody in order to
optimize its extraction. A new milling complex and offices were built along
with a camp to house contract workers. The only significant parts of the
original mine that remained in use were the headframe and shaft needed to
access the orebody. Recently, however, Goldcorp has decided to also replace
the old shaft and winze with a brand new 7,500 foot single lift, vertical shaft in an effort to speed up the mining of the new orebody and to
improve the overall efficiency of the mine.
The impact of the discovery of the new orebody on Goldcorp, the Red Lake mine and the surrounding area have been dramatic. With millions of dollars surging
into the local economy from the Red Lake Mine and the exploration efforts of
other companies hoping to duplicate the feat, the Red Lake area has
experienced a surge of prosperity and confidence not felt since the hey-days
of gold mine discoveries in the 1940s and 1950s. Now, Goldcorp is cash rich
with no debt, and is one of the most profitable mining companies in the
world.
It became apparent early in the exploration of the orebody that
visible native gold would often be encountered. The senior management of
Goldorp decided, to their credit, that if specimen-grade native gold was
encountered, some of it should be preserved as specimens to serve as a legacy
of Goldcorp, the Red Lake mine and the fantastic orebody that produced them.
David K. Joyce was retained to prepare specimens, on site and, then, to
market and sell the specimens. Since production commenced, hundreds of
beautiful, rich native gold specimens have been recovered and sold to
museums, shareholders, collectors and universities around the world.
Many mines have zones of high-grade ore that are very profitable to
mine. Few have had a zone like the High Grade Zone, however, which is still
open at depth and, although smaller in width at depth, appears to be
increasing in grade.
The property on which the Red Lake mine is located comprises
fifty-eight patented mineral claims held by Goldcorp covering approximately 2,348 acres, which, on the west side, share a common boundary with Placer Dome Ltd.'s Campbell Mine.
Goldcorp also holds mineral claims covering approximately 56,125 additional
acres of prospective mineral ground in the Red Lake area. Access to the mine
is by road and by air, with the closest major cities being Winnipeg Manitoba and Thunder Bay, Ontario.
The Red Lake mine is currently operating at a rate of 550 tons per
day of ore. Mining is accomplished using, mostly, a mechanized cut and fill
mining method utilizing jumbo drills and 5 cubic yard scoop trams. At the
present time, ore is being mined between the 31 and 37 levels, at a depth of
about 4,000 and 5,500 feet below surface. At the time of writing, ore
averaging about 2.28 troy ounces of gold per ton is being hoisted to surface.
When the new shaft is finished in 2006, production will increase to 1000 tons
per day.
The mill at the Red Lake mine uses several techniques to separate
gold from the waste rock. One circuit uses centrifugal force and gravity,
employing Knelson concentrators and a Diester jig table, respectively to
separate coarse gold from the rock. Another circuit employs flotation to
float gold rich sulphides to produce a gold-rich sulphide concentrate. Third,
a carbon-in-pulp circuit is used to capture the fine gold that is not tied up
in sulphides. Much of the concentrates produced by the above methods contain
bits of rock and other impurities. The concentrates are refined by smelting
where they are melted and the impurities are removed as a slag. The finished
products at the mine are dore bars, which are poured molten into molds, after
the refining is complete. Dore is a mixture of gold and silver with some
other minor impurities and, at the Red Lake mine, contain, on average, about
87 percent gold and 13 percent silver are poured on-site. The dore bars are
sold to refineries who further purify the gold and sell it to end-users,
financial institutions and investors. Goldcorp actually does not sell but
retains a certain percentage of its gold, in the belief that gold is
undervalued. Currently, Goldcorp owns more gold bullion than many governments
of the world!
Security is very tight at the Red Lake Mine. All people and vehicles
enter and leave the mine through a single gate. Security guards are diligent
in searching all belongings and vehicles, to ensure that gold is not smuggled
out of the mine. All people leaving the mine are required to undergo a
search, similar to those undertaken at airports, with subjects selected at
random. All briefcases and luggage leaving the mine are searched.
Regional Geology
Ontario and Quebec occupy much of the "Canadian Shield" a prolific, Precambrian age
geological formation and the home of many of the world's greatest mines, past
and present. There are many "belts" of greenstone (highly
contorted, Pre-cambrian volcanics and sediments) throughout the Canadian Shield. These greenstone belts have been the geological environments where gold
deposits are found such as: Campbell, Hollinger, Dome, Sigma, Kerr Addison,
Lakeshore, Macassa, McIntyre, Hemlo, Doyon, Bousquet, Malartic, Camflo, etc.,
all multi-million ounce producers. Goldcorp's Red Lake mine lies in the
eastern part of the Red Lake Greenstone Belt. This belt is made up of an
assemblage of ultramafic, mafic and felsic volcanic rocks with a sedimentary
sequence. These rocks are cut by a number of felsic and mafic dykes.
Styles of Gold Emplacement
The two major types of gold mineralization consist of high-grade
quartz-carbonate-sulphide mineralization grading 2.35 troy ounces of gold per
ton ("opt") and the lower grade sulphide zones grading 0.37 opt. To
reflect that variation, the zones have been grouped into two categories, the
high-grade zones (the "High-Grade Zone") and the sulphide zones
(the "Sulphide Zone").
Mineralogy
Gold Gold is the principal ore mineral at the Red Lake mine and the mineral
that is the most interesting to collectors. The gold in the High Grade Zone
was largely emplaced as a result of gold-rich, siliceous replacement of
carbonate veins and, as well, by injection into volcanic rocks. Large masses
of native gold up to many hundreds of troy ounces have been encountered
during mining. On occasion, knobs or masses of native gold can be seen
protruding from stope backs or walls. These are rich sights to behold! It is
from those places, that the most impressive specimens of native gold have
been recovered.
There appears to have been some subsequent remobilization of native
gold into fractures in quartz and carbonates (calcite, ferroan dolomite) and
into intensely altered volcanics. Arguably, the best specimens of native gold
result when the gold has formed as veinlets in these fractures. The gold
forms more coherent, solid veinlets or "leaves"in the calcite and
quartz than it does in the altered rocks. These veinlets, when exposed,
become the "leaves" and "plates" that we see in the
specimens from the Red Lake Mine. A large percentage of the native gold at
the mine occurs only as fine fracture fillings or coarse masses in altered
volcanic rock that are not suitable as specimens other than as examples of
fantastic high grade ore!!
On occasion, masses of very coarse gold are encountered in dark
gray-black quartz. This type of high-grade is slabbed and sold to lapidaries
for use in jewellery. Geologists and others interested in ore textures find
the slabbed high-grade specimens interesting, as well.
Berthierite and Stibnite The only other species that occur at the mine
that are of interest to collectors are stibnite and berthierite. Rich, high
grade-gold is, on occasion, associated with metallic black masses of coarse
stibnite and berthierite. Crystals of these minerals have not been observed
but their association with coarse gold makes for interesting specimens.
Specimen Recovery
 This specimen from the Red Lake Mine shows a
unique burst of native gold protruding from the top of the matrix of altered
volcanic rock. 8.5 cm tall. D.K. Joyce specimen and photo.
Company geologists regularly visit stopes and development headings
to gather samples and map local geology and to give direction to miners. The
geologists are accustomed to seeing native gold in the HGZ but are constantly
on the lookout for the extra-high-grade areas that are occasionally
encountered. These extra-high-grade areas are erratically distributed
throughout the mine and often run locally in the many hundreds of ounces per
ton over distances of tens of feet. These super-rich zones are often the
sources of specimen-grade-high-grade that can be prepared to produce the
beautiful gold specimens for which the Red Lake Mine is becoming famous. When
geologists encounter the super-high-grade areas, they collect any likely
looking gold-bearing ore and place it in locked, metal boxes. These boxes are
moved to the shaft, taken to surface and stored in the vault.
David K. Joyce, periodically visits the mine and works on each
individual piece of high grade to, if possible, better expose the beautiful
gold leaves, plates and other interesting formations that are enclosed in the
matrix rock and vein material. He "reads" the grain of the rock and
the directions of gold emplacement and then with a host of tools breaks,
chips and chisels away the minerals that cover the gold, in an effort to
produce aesthetic specimens that are coveted by collectors, investors and
museums around the world. The vault can be a spectacular sight when full of
native gold-bearing-hi-grade ore and finished specimens!
Interestingly, Goldcorp has retained one specimen in particular
which consists of a thick vein of nearly solid gold traversing altered
volcanic rock. The specimen is estimated to contain 298 troy ounces of gold!
Goldcorp often brings this large specimen to trade shows to tantalize people.
Conclusions
The Red Lake Mine is, based on the very high average grade of
current ore and life-of-mine ore reserves, to our knowledge, the richest gold
mine in the world. To its credit, Goldcorp has decided to recover and market
beautiful specimens of high grade ore to be sold to museums and collectors
around the world, specimens that will serve as a legacy of this orebody. They
will delight collectors, prospectors, museum visitors, and others in the
future, as they all marvel at the occurrence of so much gold, in one
place, at one time!
Acknowledgements
The authors would like to thank the management of Goldcorp for the
opportunity to be involved with specimen recovery at the Red Lake mine, for permission to publish this article and for its foresight to save excellent
gold specimens from the mine. The author would like to thank the following
people for assisting or contributing to this article: Bruce Humphrey, chief
operating officer; Chis Bradbrook, vice-president corporate Development;
Gilles Filion, vice president exploration; Claude Lemasson, mine manager; Tim
Twomey, senior geologist; Gabriela Sanchez, assistant to the chairman and
Arlene Connolly, graphic artist. We would also like to thank Professor R.
Cook for his invaluable review of the manuscript.
References:
MacGeehan, P. et Hodgson, C.J., 1982 Environments of gold
mineralization in the Campbell Red Lake and Dickenson Mines, Red Lake
District , Ontario in Geology of Canadian Gold Deposits, Canadian
Institute of Mining and Metallurgy, Special Volume 24, 184-207.
Andrews, A.J. et Hugon, H. 1985. Alteration, metamorphism and
structure associated with Archen volcanic-hosted gold deposits, Red Lake District; studies in the Campbell and A.W. White mines in Summary of field work
and other activities 1985, Ontario Geological Survey. Miscellaneous paper
no. 126, p 193-200.
Parker, J.R., Gold mineralization and wall rock alteration in the
Red Lake greenstone belt: a regional perspective; in Summary of Field Work
and other Activities, Ontario Geological Survey, Open File Report 6032,
p. 22-1-22-28
Sanborn-Barrie, m. Skulski T., Parker, J., and Dube, B. Integrated
regional analysis of the Red lake greenstone belt and its mineral deposits,
western Superior Province, Ontario; in Current Research 2000-C18;
Geological Survey of Canada, 16p.
Dube, B., Williamson, K. and Malo, M. Geology of the Goldcorp
Inc. High Grade Zone, Red Lake Mine, Ontario: an update, Geological
Survey of Canada Current Research, 2002-C26, Catalogue No.M44-2002/C26E-IN
Goldcorp Inc. Website, www.goldcorp.com
David K. Joyce Website , www.davidkjoyceminerals.com
Goldcorp publication "Outlook, 2002"
David K. Joyce is a graduate of the Haileybury School of Mines and
is a mineral dealer, adjunct professor at the University of Toronto and is also a mining business development consultant. He has worked coast to coast in Canada during his career in the mining industry. He is currently president of the Walker
Mineralogical Club and is past Chair of the Toronto Branch of the Canadian
Institute of Mining and Metallurgy.
Stephen McGibbon is Exploration Manager at Goldcorp's Red Lake Mine.
He holds a Bachelor of Science degree from Queen's University and has been
active in exploration and mining for 22 years.
Many thanks to David K Joyce for permission to include his
co-authored essay on "The Red Lake mine".
Photos
Mexico - Alan Leishman
South Africa - ML Baumann
Red Lake - courtesy of David K Joyce
Eagles Nest mine specimen - Stefan Ansermet
Further Reading:
Mexico
A Field Guide to the Gems and Minerals of Mexico - Paul Willard
Johnson 1965
Mineralogical Record
-
Mexico - Sept. -
Oct.2003 Volume 34 Number 5, Nov. - Dec.2003 Volume 34 Number 6
Gold
Rocks
and Minerals Jan.-Feb. 2004 Special Issue on Gold Vol. 79 nr 1 and 2
Lapis
Gold - A noble metal.
"Some dreams come true" - Alpheus F.Williams 1948
Postscript: The Mexican part of this essay is dedicated to
the memory of Walt Bowser, the best guide for mineral collectors in Mexico, and for his humanitarian work with the Mexican people.
Alan Leishman
Alan Leishman is now
retired in Switzerland following a career in international commerce
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