When some think of gold, the word karat may come to mind. Or is it carrot or maybe carat? So did I just pan a vegetable, a piece of gold, or a diamond from that stream?
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| Schematic cross section through an ideal kimberlite pipe showing carrot-shaped diamond pipe. Generally, the vertical column from the blow to the maar is about 5,000 feet. The blow is the enlargement at the base of the pipe, and the maar is the volcanic orifice. |
If you are a rabbit, possibly you were hoping to pan a carrot - but then again, you wouldn't be reading this blog. Carrots are good sources for vitamin A and good for attracting rabbits.
I tried my green thumb in Gilbert Arizona last summer and planted carrots only to discover few edible things grow in the Phoenix valley in the summer (other than prickly pear cactus - and its questionable if many of us would try to peel the skin off the cactus just to eat the slimy plant). All of my carrots deep-fried in the ground as temperatures soared into triple digits for a month.
I still have difficulty adapting to Arizona’s hot weather after living in Wyoming much of my life. But someone told me the other day that Arizona is like Wyoming, just in reverse. People just don’t go outside when temperatures hit -50oF in Wyoming (although I always skied to work when temperatures fell below -30) and they don’t go outside when temperatures rise above 110oF in Arizona. I never thought of it that way. But at least in Wyoming, my Nissan truck had a heater; in Arizona it doesn't have an air conditioner (didn't need one in Wyoming). One day I'll have to break down and buy a new truck with AC.
I tried my green thumb in Gilbert Arizona last summer and planted carrots only to discover few edible things grow in the Phoenix valley in the summer (other than prickly pear cactus - and its questionable if many of us would try to peel the skin off the cactus just to eat the slimy plant). All of my carrots deep-fried in the ground as temperatures soared into triple digits for a month.
I still have difficulty adapting to Arizona’s hot weather after living in Wyoming much of my life. But someone told me the other day that Arizona is like Wyoming, just in reverse. People just don’t go outside when temperatures hit -50oF in Wyoming (although I always skied to work when temperatures fell below -30) and they don’t go outside when temperatures rise above 110oF in Arizona. I never thought of it that way. But at least in Wyoming, my Nissan truck had a heater; in Arizona it doesn't have an air conditioner (didn't need one in Wyoming). One day I'll have to break down and buy a new truck with AC.
Carrot comes from the French carotte that refers to the favorite food of that old "wascal wabbit". It has nothing to do with the other two homonyms carat and karat; except that diamond
exploration geologists like to use the shape of a carrot to describe what the
cross-section of a diamond pipe (kimberlite volcano) might look like, but this is as close
to diamonds a carrot gets.
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| One of the more than 300 cryptovolcanic structures discovered in the Colorado-Montana-Wyoming kimberlite (diamond) province (Hausel, 2014). This depression is filled with water in the spring, but has an unexplained vegetation anomaly, enriched carbonate soils. The anomaly is circular and characteristic of many diamond pipes in the Colorado-Wyoming State Line region. |
Diamond pipes
are largely carrot-shaped because they erupt with large amounts of highly pressurized gas and shoot out of the earth's mantle like a shotgun blast producing a maar-like volcano. When the kimberlite magma breached the earth’s surface, the
eruption was explosive with magma ejected with country rock boulders and
highly pressurized gas (water vapor and carbon dioxide). Some researchers
suggest gaseous emplacement velocities could
have been as rapid as Mach 3.
So much carbon dioxide was present in these
eruptions that the EPA would have issued a citation to Mother Nature for
releasing these toxic(?) fumes. (In 2009,
Obama’s EPA listed carbon dioxide as an air pollutant. Prior to 2009, carbon
dioxide was just a simple gas or plant food used by all plants, algae and many forms of
bacteria needed to produce organic compounds and release the oxygen we all breathe [you know its coming, Obama will likely tax us for using oxygen]. It's good our government is watching out for us, otherwise we would not have been
aware that such an important gas required for life was a
pollutant).
Kimberlite (diamond) pipes (unless deeply eroded) have circular expressions in plan. This expression often looks like an impact crater. To see some very impressive diamond pipes, I recommend searching the Internet for “Ekati Airport, NWT” to see Canada’s premier diamond mining operation. Now search for the “Big Hole Kimberley, South Africa”. This is another diamond pipe that was operated years ago and looks like an impact crater. Search throughout the Kimberley city limits and you’ll find other diamond pipes.
Now take a look at Russia. Search for “Mir Mine, Russia” also known as Mirnyy Diamond Mine. This will take you to one of the more impressive circular pipes. While you are looking at these areas, remember kimberlites almost always occur in clusters and often line up on linear fractures. In these three areas, you may find other circular anomalies that have not been mined that are likely kimberlite pipes.
In addition to finding the circular to roughly circular depressions, one needs to look for other characteristics, such as a group of circular to elongated depressions lining up on some kind of lineament. For example, take a look at the Lost Lakes in the Red Feather Lakes region of northern Colorado. You will find a group of lakes and depressions that sit on a distinct linear fracture that trends about N30oE. And when you take a look at the lakes along the northeastern extent of this fracture - wow - the lake shores look like they are coated with salt or blue ground. Several years ago, I visited these anomalies, and the soils are very carbonate rich - if you drop some dilute HCl acid on the soil, it will fizz. The country rock in the region is mostly granites and amphibolites which do not have any known carbonate. Now these are excellent cryptovolcanic structures and possible kimberlites.
Years ago, I also came across a cluster of depressions in the Indian Guide district of Albany County Wyoming. All of these are situated along N-S to northwesterly fractures immediately west of the Iron Mountain kimberlite district, where dozens of kimberlites (including a couple of diamonds) were found years ago (Hausel and others, 2003). I tried to get the State to provide me with a grant to drill these, but to no avail. The state was much more interested in providing another agency with money to see how high a rare and endangered jumping mouse could jump (it turns out this rare mouse was not so rare after all - just a normal field mouse that was startled). So these cryptovolcanic structures remain unknown as to why they exist - but the fact they are sitting along the western trend of the Iron Mountain kimberlites strongly suggest Wyoming is losing its marbles, or should be say, carats.
Now take a look at the Twin Mountains Lakes area near Cheyenne. I identified more than 50 interesting structures (depressions and lakes) in this area that are situated in a distinct regional fold in the Proterozoic amphibolites that could be an extension of the State Line kimberlite district. Some appear to be very large - could these be kimberlites? No one has ever drilled or sampled these and they look like good targets to me.
Now take a look at the Kelsey Lake kimberlites in Colorado. These were mined for a short time and produced many high-quality gemstones including a 28.3-carat diamond along with a diamond fragment from a stone estimated to have been about 80 to 90 carats (Hausel, 1998, 2014). As you examine Kelsey Lake, keep in mind this was at one time a diamond mine (1996) and there are at least two reclaimed kimberlites and much of the diamond ore was never mined due to legal problems. Also note there is still fresh blue ground exposed in the reclaimed area. In this region, there are also several unmined kimberlites - I know, because I mapped them years ago. They are all located in my new book.
Now here is something you want to really think about! The Kelsey Lake kimberlites sit right on the edge of Fish Creek and a small tributary to the south of the pipes. These streams must be filled with diamonds! In southern Africa, it was noted diamonds from the Kimberley region were transported more than 600 miles in the Orange River to the coast of western Africa. Now imagine where could all of those diamonds that eroded from Kelsey Lake be. Personally, I would map out Fish Creek and follow it and associated drainages for at least a hundred or more miles down stream.
When one diamond company was taking samples for kimberlite in this area, they recovered a group of diamonds including a 6.2 carat gemstone in Fish Creek near Kelsey Lake - and they were NOT even looking for placer diamonds.
Recently, I was notified by a prospector who read my book on Finding Gemstones, that he panned out a cache of diamonds including one just under 5-carats in weight out of a stream I had identified that would be an important diamond placer. Remember, tiny diamonds are almost worthless (as the boys on Gold Rush discovered in South America). But large gemstone diamonds can be valuable.
If you decide to search the area for diamonds, there is a lot of private property, but also remember a couple of other things: (1) Fish Creek is long, (2) gem-quality diamonds can survive stream transport of at least 600 miles, (3) kimberlites yield other gemstones known as diamond indicator minerals, and (4) the State Line kimberlites have been eroded off and on for the past 600 million years and the largest portion of the kimberlite pipes (the mouths) have been eroded and the diamonds carried downstream (see the schematic cross section through a kimberlite above). It has been estimated that 2000 to 3000 feet of vertical column of kimberlite pipe in this area has been eroded. So, what are you waiting for?
Now, if you have one troy ounce of gold worth about $1800 and compare this to a rare, pink, Argyle pink diamond worth about $1,000,000 per carat (unfortunately, I don’t have any Argyle Pinks), you will get a good idea at the incredible value of some gemstones. A one-carat rare pink diamond could be worth about 150 times more than a equivalent weight in gold! Not bad for a little crystal.
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| Distinct depression associated with a diamond pipe in Colorado. The diamond pipe sits under an open, grass-covered park. Many kimberlites lack tree growth and often give people an impression of an impact crater. This cryptovolcanic structure was trenched and diamonds along with kimberlite were recovered at shallow depth. Also note the fault trace marked in red. As a prospector, you should always walk these traces out as far as they go simply because more than one kimberlite often erupted along the same fracture. This is how I discovered some kimberlites in this region that were missed by others. |
Kimberlite (diamond) pipes (unless deeply eroded) have circular expressions in plan. This expression often looks like an impact crater. To see some very impressive diamond pipes, I recommend searching the Internet for “Ekati Airport, NWT” to see Canada’s premier diamond mining operation. Now search for the “Big Hole Kimberley, South Africa”. This is another diamond pipe that was operated years ago and looks like an impact crater. Search throughout the Kimberley city limits and you’ll find other diamond pipes.
Now take a look at Russia. Search for “Mir Mine, Russia” also known as Mirnyy Diamond Mine. This will take you to one of the more impressive circular pipes. While you are looking at these areas, remember kimberlites almost always occur in clusters and often line up on linear fractures. In these three areas, you may find other circular anomalies that have not been mined that are likely kimberlite pipes.
In addition to finding the circular to roughly circular depressions, one needs to look for other characteristics, such as a group of circular to elongated depressions lining up on some kind of lineament. For example, take a look at the Lost Lakes in the Red Feather Lakes region of northern Colorado. You will find a group of lakes and depressions that sit on a distinct linear fracture that trends about N30oE. And when you take a look at the lakes along the northeastern extent of this fracture - wow - the lake shores look like they are coated with salt or blue ground. Several years ago, I visited these anomalies, and the soils are very carbonate rich - if you drop some dilute HCl acid on the soil, it will fizz. The country rock in the region is mostly granites and amphibolites which do not have any known carbonate. Now these are excellent cryptovolcanic structures and possible kimberlites.
Years ago, I also came across a cluster of depressions in the Indian Guide district of Albany County Wyoming. All of these are situated along N-S to northwesterly fractures immediately west of the Iron Mountain kimberlite district, where dozens of kimberlites (including a couple of diamonds) were found years ago (Hausel and others, 2003). I tried to get the State to provide me with a grant to drill these, but to no avail. The state was much more interested in providing another agency with money to see how high a rare and endangered jumping mouse could jump (it turns out this rare mouse was not so rare after all - just a normal field mouse that was startled). So these cryptovolcanic structures remain unknown as to why they exist - but the fact they are sitting along the western trend of the Iron Mountain kimberlites strongly suggest Wyoming is losing its marbles, or should be say, carats.
Now take a look at the Twin Mountains Lakes area near Cheyenne. I identified more than 50 interesting structures (depressions and lakes) in this area that are situated in a distinct regional fold in the Proterozoic amphibolites that could be an extension of the State Line kimberlite district. Some appear to be very large - could these be kimberlites? No one has ever drilled or sampled these and they look like good targets to me.
Now take a look at the Kelsey Lake kimberlites in Colorado. These were mined for a short time and produced many high-quality gemstones including a 28.3-carat diamond along with a diamond fragment from a stone estimated to have been about 80 to 90 carats (Hausel, 1998, 2014). As you examine Kelsey Lake, keep in mind this was at one time a diamond mine (1996) and there are at least two reclaimed kimberlites and much of the diamond ore was never mined due to legal problems. Also note there is still fresh blue ground exposed in the reclaimed area. In this region, there are also several unmined kimberlites - I know, because I mapped them years ago. They are all located in my new book.
Now here is something you want to really think about! The Kelsey Lake kimberlites sit right on the edge of Fish Creek and a small tributary to the south of the pipes. These streams must be filled with diamonds! In southern Africa, it was noted diamonds from the Kimberley region were transported more than 600 miles in the Orange River to the coast of western Africa. Now imagine where could all of those diamonds that eroded from Kelsey Lake be. Personally, I would map out Fish Creek and follow it and associated drainages for at least a hundred or more miles down stream.
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| Gem-quality diamond indicator minerals from the Sloan kimberlites, Colorado |
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| Diamond indicator minerals (chromian diopside to the left and pyrope garnet to the right) in Sloan kimberlite specimens. |
Recently, I was notified by a prospector who read my book on Finding Gemstones, that he panned out a cache of diamonds including one just under 5-carats in weight out of a stream I had identified that would be an important diamond placer. Remember, tiny diamonds are almost worthless (as the boys on Gold Rush discovered in South America). But large gemstone diamonds can be valuable.
If you decide to search the area for diamonds, there is a lot of private property, but also remember a couple of other things: (1) Fish Creek is long, (2) gem-quality diamonds can survive stream transport of at least 600 miles, (3) kimberlites yield other gemstones known as diamond indicator minerals, and (4) the State Line kimberlites have been eroded off and on for the past 600 million years and the largest portion of the kimberlite pipes (the mouths) have been eroded and the diamonds carried downstream (see the schematic cross section through a kimberlite above). It has been estimated that 2000 to 3000 feet of vertical column of kimberlite pipe in this area has been eroded. So, what are you waiting for?
The Carat
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| A flawless, 1,720 carat iolite gemstone I found at Palmer Canyon Wyoming with some sapphire, ruby, and kyanite gemstones - now that's a lot of carats. |
So where do pink diamonds come from? The pink in diamonds is thought to be the result of shear stress on the diamond, and such gems are thought to form at depth in a subduction zone unlike other diamonds mined in most kimberlites. The great majority of pink diamonds have been mined along the northern coast of Australia at the Argyle mine. To see this mine on Google Earth, search for “Argyle Lake, Australia” and the mine is a short distance southwest of the lake. Very recently, the largest pink diamond ever found was recovered from the Argyle mine. Described by many news outlets as a giant diamond, this one is only 12.76 carats (probably around 12 to 14 millimeters across or a little more than a half inch). As a comparison, the largest diamond ever found was the Cullinun that weighed 3,106 carats). But because of its rarity and color, the Pink Jubilee diamond may sell for as much as $10 million. When cut and polished, it will of course be even smaller.
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| A group of very expensive Argyle fancy diamonds on display at the Argyle mine in Australia. I asked, but they wouldn't let me have any of these. |
The Karat
Now let’s look
at another word that sounds like the other two words - the karat. Karat also has little to do with rabbits and vitamin A unless you purchase a gold pendant
in the shape of a rabbit. Karat
refers to purity of precious metals in jewelry.
When you recover gold in the nearby mountains, it could be nearly pure, yellow gold or could be not quite as pure brassy electrum. Natural electrum refers to a mixture of gold and silver (>20% silver) that is sometimes referred to as white gold.
When you recover gold in the nearby mountains, it could be nearly pure, yellow gold or could be not quite as pure brassy electrum. Natural electrum refers to a mixture of gold and silver (>20% silver) that is sometimes referred to as white gold.
Natural gold (or
precious metals in general) is alloyed with other metals including silver, platinum,
palladium, copper, nickel and other metals. It is seldom pure (99.9%) and must
be purified to produce the golden metal with few alloys. The purer the gold,
the more malleable, soft, heavy and noble
(resistant to oxidation and corrosion) is the metal.
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Gold from Rock Creek Wyoming mined a short distance downstream from several gold-bearing lodes. This gold is a little whiter (brassy) than gold from some other nearby localities and likely has some silver. Some gold in this area was tested and found to contain as much as 11% silver.
The Rock Creek placer mine was closed by a 1942 War Minerals Board order. This suggests that the World War II miners were recovering gold worth $34/ounce at a profit. Today, gold prices are 50 times higher. Thus this placer likely is still minable. To visit this placer on Google Earth, search for “Atlantic City, Wyoming”. Atlantic City sits in the upper part of the Rock Creek placer and is the place I figured I would have retired and ending up working for the Prospecting and Mining Journal - but things didn't quite work out that way. Now instead of shoveling tons of snow, I'm basking in the sun.
There are many other placers in this region that contain minable gold. One may be Willow Creek that runs through South Pass City. Willow Creek has a relatively small volume of gravel, but its location (cutting across the Carissa lode, the principal gold-bearing lode in the district) guarantees it will have rich pay streaks. However, Willow Creek was closed to mining by the Wyoming Department of Environmental Quality due to the toxic levels of mercury (whether imagined or real). During my research of this region over a seven year period, I did not find any evidence of primary mercury in the district and the possibility of large quantities of mercury being dumped in the creek by 19th century miners is unrealistic. Mercury was a valuable commodity in the 19th century. If some mercury were actually lost in the creek in the 19th century, it would have been a very small, finite source and mining would only serve to clean the creek bed.
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Pure gold is designated
as 24-karat by jewelers: 24-karat gold being the purest at 99.9% gold that is also
referred to as 0.999 fine. Being essentially pure, 24-karat gold is soft and can
be difficult to some jewelry applications where a wearer of the metal has an
active life style. This is because the malleability of pure gold insures such
jewelry will be easily scratched. Gold purity can be defined by the formula:
P(karat weight) = 24 x Mpg/Mt (mass of pure
gold /total mass of the material).
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| Yellow gold from Smith Gulch at South Pass, Wyoming. Two prospectors recovered 20 ounces per week while prospecting Smith Gulch in the 1980s using a small backhoe and a trammel. And keep in mind, this was a placer that supposedly had already been mined out. |
Some jewelry is
listed as 18-karat gold (18/24=0.750 fine). This consists of 75% gold. Another
common mixture is 14-karat gold (14/24=0.583 fine) (58.3% gold); and 12-karat gold
(12/24=0.500 fine) (50% gold).
12 karat gold = 12/24 = 0.500 (fine)
0.500 x 100 = 50%
Metals often alloyed
with gold include nickel, copper, palladium, manganese, silver, zinc, aluminum,
iron, gallium, indium, ruthenium, platinum, palladium and rhodium. By using
various alloys, gold can be hardened or it can change color.
Using nickel and
silver will give gold a subtle white appearance to yield white gold. The nickel provides not only white color, but gives the
noble metal strength. However, some people are allergic to nickel. In this case,
palladium, platinum, or rhodium can be used to substitute for nickel in white
gold. Platinum-group metals are inert just like gold and will not produce
allergic reactions (but they cost a lot more than nickel).
Rose and pink
gold is formed by using copper as an
alloy. The more copper, the deeper the pink color. The use of copper was
popular in Russia in the past and this became known as Russian gold, which is now archaic, but the term still persists in the
literature. Rose gold is 18-karat gold with 25% copper. Red gold is 12-karat
gold (50%) with about 50% copper.
By adding zinc,
one can produce less malleable and harder gold. Cadmium can be used to produce green
gold. Other varieties include black, purple or blue gold. Purple or amethyst
gold is a mixture of gold and aluminum that is 18-karat and brittle. Blue gold
is produced by adding indium or gallium to 12- or 14-karat gold. By adding
certain metals to gold, the gold can become more and more brittle, more
corrosive, and may even discolor in contact with skin.
So karat is not a vegetable, but instead a
measure of purity. If we were to weigh gold, the precious metal is weighed in
ounces or measured in grams. But, then there is an ounce, and there is an ounce.
When is an ounce an ounce?
Weighing precious
metals has caused considerable confusion. This is because there are two different
ounces and few people indicate which ounce they are dealing with and not
everyone uses the proper ounce for weighing precious metals. Most have the
impression there are 16 ounces in a pound. Well, this is true when you are
weighing something besides precious metals. The avoirdupois ounce we see on our bathroom scales when we weigh
ourselves in the morning is the unit used to weigh objects in most English
speaking countries. It comes from the Old French aver de peis which is interpreted to mean weight of goods. So how much your goods weigh in the morning is a
result of how much indulgence you had during the previous night.
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| A 24 ounce gold nugget from Rock Creek Wyoming. |
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| The fire assay furnace at the Vulture mine, Arizona. Yes the assay house needs a little cleaning. |
References:
Boyle,
R. W., 1987, Gold – History and Genesis
of Deposits: Van Nostrand Reinhold Company, 676 p.
Erlich,
E.I. and Hausel, W.D., 2002, DiamondDeposits – Origin, Exploration and History of Discovery: Society of SME,
374 p.
Hausel,
W. D. and Hausel, E.J., 2011, Gold –Field Guide for Prospectors and Geologists (Wyoming and Adjacent Areas):
CreateSpace, 365 p.
Hausel,
W. D. and Sutherland, W.M., 2000,
Gemstones and Other Unique Minerals and Rocks of Wyoming – A Field Guide forCollectors: Wyoming State Geological Survey Bulletin 71, 268 p.
HEY, there are many OLDER posts - be sure you look at them
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