Sunday, February 28, 2016

Diamonds, Rubies, Garnets from the Great Diamond Hoax

Some of the left over 1872 'salt' collected on Table Rock north of Diamond Peak by the author. This sample includes 4
pink red ruby with reddish to reddish brown pyrope and almandine garnets. On my first excursion to the great diamond
 fields, I had collected 4 diamonds, 17 rubies and 24 pyrope garnets from table rock. Unfortunately, I agreed to let Dr.
Hilpert borrow these samples to weigh, examine and photograph for a book he was working on for the US
 Geological Survey. Then he passed away and my samples ended up in his daughter's hands and I was not able to recover
them. Apparently she wanted a fortune for my samples. Chalk up another one to experience - NEVER lend specimens
to anyone!
More than a century ago, the southern Green River Basin of Wyoming and Colorado was the site of a mining swindle in which thousands of diamonds and other gemstones were used to salt a sandstone outcrop near the borders of Colorado, Utah and Wyoming. This event shocked the financial markets of the country and left an imprint in the form of geographic place names throughout much of the western U.S. as many prospectors searched for the fabled diamond fields. As a result, many geographic names that now bare the name "diamond" in Arizona, Colorado, Nevada, New Mexico, Utah and Wyoming, were a result of prospectors searching for the location of the diamond fields.

This event involved several affluent individuals of the time including Civil War generals, a U.S. Senator, and two presidential candidates and resulted in the formation of more than 25 companies with a total capitalization of more than $250,000,000 to search for diamonds in the US. This Great Diamond Hoax occurred 2 miles south of the Wyoming border in Colorado, just about 15 miles east of the Utah border. You can find this area by search for "Diamond Peak, Moffat County, Colorado" on Google Earth. The location of Diamond Peak is 40°57'4"; 108°52'41"W. More than one Diamond Peak is found in Colorado. Another peak in Larimer County resides along the edge of the Colorado-Wyoming State Line diamond district and reportedly has a small diamondiferous kimberlite along the foot of this peak (40°58'46"N; 105°33'35"W).

Kelsey Lake diamond mine highwall, Colorado
History of Diamond Discoveries. Although diamond and its unique physical properties had been known for nearly 3,000 years, but in 1872 essentially no one in North America had any first hand experience with raw diamonds. This fact was used effectively to promote a diamond fraud of great magnitude at this time in history" 

By 800 BC, diamonds had been discovered in alluvial gravels in India. India remained the principal source of diamonds for the world until diamonds were discovered in alluvial deposits in Brazil in 1725 AD (for those of you who are Wyomingites, you might be interested in knowing that one company searched the Medicine Bow Mountains in the early 1980s for Witwatersrand-type of paleoplacer gold similar to some Brazilian deposits and recovered one core sample containing 10 ppm gold, and another core sample of metaconglomerate with a diamond).

By 1839, the Brazilian diamonds were thought to have been found in situ in the Minas Gerais region of Brazil in a rock called "itacolumite", a micaceous sandstone with interlocking quartz grains. Because of this discovery, itacolumite was considered as the primary host for diamond. This source was so ingrained in the thinking of people in the 1800s, that following the discovery of diamonds in placers in South Africa, a well-known jeweler from London pronounced the South African diamond discoveries to be fraudulent, as no rock resembling itacolumite had been found in the area.

Even so, diamonds were found in 1866 and 1867 in alluvial gravels near the confluence of the Vaal and Orange Rivers not far from the present site Kimberley, South Africa. This discovery led to the "wet diggings" diamond rush in Africa, but the source of the diamonds remained unknown.

Molly Lake - example of a pan (depression) often found over
diamond-bearing kimberlite.
In 1869, diamonds were discovered in mud used in the construction of some nearby farm buildings in the Kimberley region. The mud was mined from shallow, water-filled, depressions known as "pans". These pans and dry creeks, locally termed "dry diggings" . 

In 1871, when plans for the great diamond hoax were formulating in North America, the origin of the dry diggings in South Africa was still a mystery. The South African diamonds were recovered in the mud pans with calcareous talcose soil and rubble containing mica, chromian diopside, pyrope garnet, picroilmenite, and angular to rounded boulders. The rounded boulders were initially thought to had been stream worn, although we now know these megacrysts and nodules were derived from the earth's mantle and abraded in kimberlite magma during transport to the earth's surface. The true essence of the pans remained elusive for a few more years until it was realized the pans actually represented eroded depressions over diamondiferous kimberlite.

Blue ground (muddy diamond-bearing clay) at the Schaffer complex kimberlite, Wyoming exposed in a dozer trench in
1979. The blue ground is a montmorillonite clay - or a 'calcareous talcose soil' formed from decomposed kimberlite.
So when 1872 came around, some researchers began to regard the dry diggings in South Africa as being eruptive in origin and the term "pipe" was introduced in the literature in the following year. It was not until 1886, that sufficient interest in the host rock for diamonds led to its description, and the rock was described as a mica-bearing peridotite porphyry and was termed 'kimberlite'.

Great Diamond Hoax. The initial idea of the diamond hoax was conceived by James B. Cooper, a bookkeeper for a diamond drill company in San Francisco. After the hoax was revealed in late 1872, Cooper admitted with noble condor to an inquiry board that the diamond hoax was his idea, and testified he had suggested the hoax to his two co-conspirators, Phillip Arnold and John Slack, as a pleasing variation on the salting of gold or silver mines. 

Phillip Arnold, soon became the principal character in the hoax. Working through Cooper, Arnold got hired as an assistant bookkeeper of the diamond drill company. While in this capacity, Arnold learned all he could about diamonds, examined the many samples around the office, and studied books on the gemstone. In short, Arnold became the only expert in uncut diamonds in North America, in the 1870s. 

Asbury Harpending, a Kentucky gentleman.
After growing up in Kentucky, both Arnold and Slack became adventurers and prospectors. Following the discovery of gold at Sutter's Mill in California in 1948, both set off for the gold fields. By 1855, Arnold and Slack were in the heart of the gold fields and it was during this time that they became acquainted with another fellow Kentuckian by the name of Asbury Harpending. 

Harpending was one of California's foremost financiers, and a close, intimate friend of Arnold and Slack. Harpending, a southern gentleman from Hopkinsville, Kentucky, had many mining interests, although Harpending had been implicated in some plots possibly related to salting of some gold properties in California.

Harpending had hired Phillip Arnold at the Lincoln Gold Quarry mine in Placer County, California. Harpending's partner in the gold mine was George Roberts, who would later become a member of the Board of Directors of the diamond company formed to develop the diamond fields. 

In 1871, Arnold, Slack, Cooper and Harpending visited some mines in New Mexico. Harpeding left the area, and Arnold, Slack and Cooper stayed in New Mexico for some time prior to returning to San Francisco in early 1871. On their return trip to San Francisco, they rode through the Fort Defiance area of Arizona and collected a suite of minerals reported to be rubies, black diamonds, sapphires, and spinels from a group of ultrabasic diatremes in the Navajo volcanic field. (Author's note: The assemblage probably included pyrope garnet, almandine garnet and chromian diopside, but rubies, diamonds and sapphires are not known from the Navajo Volcanic Field).

The stones were taken back to California and were identified as rubies by a jeweler in San Francisco, but the validity of the black diamonds were doubted. Thus Cooper later mixed some diamonds from the diamond drill company's stock with the Fort Defiance minerals, and the stones were submitted to Frontier, Bellmere and Company for appraisal. The appraisal included a certificate stating the mixture contained authentic diamonds. For some unknown reason, Cooper then became a silent partner in the scam.

Armed with the certificate, Arnold and Slack approached George Roberts describing a discovery of a vast diamond field, and requested him to keep the discovery a secret. Roberts however, wrote to Harpending in London, and also told William Ralson (a Californian banker) about the discovery. 

Rough diamonds from undisclosed locations.
Harpending soon received cables from Ralston indicating that diamonds of limitless quantities could be gathered at nominal expense, and that he and Roberts were in practical control of the estimated $50,000,000 proposition. Harpending agreed to return to America, with a friend and partner Alfred Rubery, and a meeting was scheduled in New York City to discuss possible plans to form a company to develop the diamond fields. General George S. Dodge and William Lent (both of whom made fortunes selling gold and silver mines on the Comstock Lode in Nevada), where included as investors.

The investors were not convinced of the diamond discovery. So Arnold and Slack said they would go back to the fields and "bring out a couple of million dollars worth of stones". Instead, Arnold and Slack went incognito to London to purchase $19,440 worth of rough, poor-quality, diamonds and rubies from the Leopold Keller & Company. 

Upon their return, Arnold and Slack meet with Harpending in San Francisco. Upon receiving the stones, plans were made to form a company to develop the diamond fields and it was decided to: (1) send a sample to Tiffany of New York for examination and appraisal; and (2) find a mining consultant to investigate the property in the spring.

To complete the first part of the plan, Harpending, Arnold, Slack and others went to New York with about 10% of the gemstones, and met with a group of influential people that included Charles Tiffany (of Tiffany of New York), General George B. McClellen (the former Commander in Chief of the Union Armies who opposed Lincoln for the presidency), Senator Ben Butler, and Horace Greeley (editor of the Tribune and soon to be an unsuccessful Presidential candidate). At the appraisal, Tiffany declared the stones to be authentic diamonds, rubies, emeralds, and sapphires. Two days later, Tiffany's appraised the stones at $150,000, many times their actual value. Since this was only about 10% of Arnold's and Slack's gemstones, Harpending declared the entire collection to be worth $1,500,000. Slack at this point, wanted to sell his remaining interest in the diamond fields, and William Lent paid him $100,000 with Arnold's consent to have the gems held as security.

Henry Janin, Mining Engineer
The second part of the plan was completed by hiring one of the most conservative and well-respected mining engineers in the country. Henry Janin, the trusted mining advisor of the Bank of California, was considered one of the best mining engineers in the world with few peers in the US. He had examined hundreds of mining properties as a consultant without a single investor every losing a dime based on his judgement. 

The group also solicited the expertise of Senator Ben Butler (by providing him 1000 shares of stock in the company - sounds like politicians have always been the same). Butler engineered an amendment to the Placer Mining Act to cover diamonds on May 10, 1872. 

Harpending and Dodge made plans to visit the property with Henry Janin in the spring of 1872. Because of the impending visit, Arnold and Slack needed to find a suitable place for the diamond fields, and conspirators decided on a locality relatively near the UP railroad, and needed more gemstones for salt. 

In December, 1871 they returned to London and purchased an additional $8,575 worth of rough diamonds and rubies (nearly10 pounds). Upon returning from London, they also picked up nearly 50 pounds of garnets and other minerals from the Ft. Defiance area. 

The Diamond Company. On October 31, 1871, the Golconda Mining Company, a New York Corporation, was formed with a capital stock of $10,000,000 of which $2,500,000 was be assigned to Arnold. Arnold also received $550,000. 

The interest in diamonds grew at a fever pace, and a minimum of 25 companies were formed to search for diamonds in 1872. Some of the more aggressive firms sent prospectors into the Fort Defiance area, where Kit Carson had claimed to have found rubies many years before.

Others sent prospectors in the search of reported gemstones described Jim Bridger. Bridger purportedly claimed diamonds and sapphires could be picked up in gravel on the plains of southern Colorado and northern and eastern Arizona. Bridger also described one area where everything had turned to stone (both animate and inanimate objects) and was perfectly preserved with a variety of gems. 

Diamond Fields Speculation. The discovery of diamonds in the US had a tremendous effect, and was as great as the interest generated for gold in California. The Laramie Daily Independent stated that there was $250,000,000 in diamonds on the ground. The San Francisco Chronicle (1872) reported, "... the value of the property is far beyond that of any mining property ever discovered on the coast."

Map showing the Location of the Great Diamond Hoax (after Hausel and Stahl, 1995).
Speculation led to the naming of many geographic features such as Diamond Mountain north of Vernal, Utah, and Diamond Peak south of Laramie, Wyoming. 

Table Rock in the Red Desert of Wyoming was suggested to be the site of the diamond fields, and was initially named Diamond Mesa.

Colorado's Governor, William Gilpin fueled speculation in a talk on the diamond fields entitled, "Diamond regions of Colorado and New Mexico." In the following week, Gilpin provided an interview to the Rocky Mountain News providing intricate details of the diamond fields in San Juan County.

The actual location was selected by Arnold about 40 miles south of the closest station on the railroad known as Black Buttes station. Arnold selected an outcrop of ferruginous sandstone in the Green River Formation at the base of the northeastern flank of prominent peak (Diamond Peak) two miles south of the Wyoming border in what is now known as Diamond Field Draw in Moffat County, Colorado. 

Approximately 60 miles west-northwest of the diamond hoax site are hundreds of anthills located along the northern edge of Cedar Mountain that contain pyrope garnet, chromian diopside, and other mantle minerals similar to those used as salt by Arnold and Slack. The source of these kimberlitic indicator minerals has yet to be determined (McCandless, 1979).

The GemHunter, aka Dan Hausel, shows prospectors diamond indicator
minerals in anthills in the Green River Basin of Wyoming.
Even more amazing is the top of Diamond Peak adjacent to the diamond hoax site contains exposures of Bishop Conglomerate. This conglomerate contains some detrital pyrope garnet and chromian diopside similar to the grains in the anthills north of Cedar Mountain. The morphology of the diamond hoax garnets and those of the Cedar Mountain ant hills are different, and the diamond hoax grains are similar to the four corners garnets (Tom McCandless, personal communication, 1995).

Verification of the Fields. On June 1, 1872, the group of investors including Harpending, Dodge, Lent, and Rubery left with Slack, Arnold, and Janin for the diamond fields from Rawlins Springs (currently known as Rawlins). Rawlins was nearly twice as far from the diamond fields as Black Buttes Station, but this was apparently done to make the horseback ride seem longer than it really was in order to create the illusion that the fields were located a great distance from the railroad. Along segments of the trip, the investors and Janin were blind-folded to keep the location secret. 

Outcrop of Bishop Conglomerate at
Cedar Mountain, Wyoming
Sample of Bishop Conglomerate with chromian diopside
On the fourth day, they arrived at the diamond fields. The party began digging and panning for diamonds and recovered over 500 diamonds, rubies, sapphires, and emeralds. 

By bedtime, the entire party was exuberant at being thrust into boundless wealth. Janin was wildly enthusiastic because his option on 1,000 shares of mining stock seemed to be zooming in value, and his name would soon be associated with one of the most important mining ventures in North America. The party quit sampling and spent the remaining time staking claims. Three thousand acres were staked.

When the group returned to New York, Janin made his stating they had recovered 824 carats of diamonds, 7,200 carats (4 pounds) of rubies in just four working days, from 3,000 pounds of gravel. It was also reported that the property covered at least 3,000 acres of ground, although Janin had only sampled a small portion of a 160 acre block. Janin was so taken in by the fraud it was suggested that there were enough rubies and diamonds in a single gulch to purchase the entire city of New York. 

Some of the many pyrope garnets and chromian diopsides
collected at Cedar Mountain.
Janin's report convinced most of the investors that they were literally sitting on top of a diamond mine. Because of the favorable results, Lent paid Arnold another $300,000. Ralston insisted on another examination of the property to be headed by George Roberts and Arnold slipped back into the fields to plant another $20,000 in stones prior to meeting the Roberts party in Laramie August 1872. 

The Roberts party went to the field to survey the claims and a town site to be named "Brilliant City". The Chronicle quoted Roberts as saying, we have fully confirmed the truth and accuracy of Mr. Janin's report - more than confirmed it, in fact". The article reported the group had recovered 384 diamonds with some sapphires, rubies, and garnets.

40th Parallel Survey. After hearing many rumors and reading various newspaper accounts about the newly discovered diamond fields, Clarence King The 40th Parallel Survey became concerned that the fields may be within the boundaries of their Survey. 

By mere coincidence, on October 5, 1872, Samuel Emmons and James T. Gardner of the Survey, ran into Janin on a west bound train as he boarded to meet some members of the field crew sent to the diamond fields. Through conversations between various individuals of the Survey and members of Janin's party, they were able to piece together seemingly insignificant bits of information that provided them with a fairly good idea of the location of the diamond fields.

Hey, I thought I saw these guys in the Cowboy Bar in Laramie.  Well, actually
 this is an old photo of the 40th Parallel Survey including Clarence
King (far right).
Discovery of the Hoax. On Tuesday, October 29th, 1872, members of the 40th Parallel Survey met at Fort Bridger to search for the diamond fields. On the 4th day out King and Emmons found a small, fresh, blaze on a cottonwood that had a claim notice signed by Henry Janin.

Circling around, they soon found tracks which led them up on the flats. On the flats, they found additional mining claims that led them to a iron-stained, coarse-grained sandstone outcrop about 100 feet long exposed along the edge of the gulch where many tracks converged. The three dismounted and began examining the outcrop. In an instant, Emmons found a ruby. Wilson then found a translucent grain which they all tested its hardness until they were convinced it was a diamond.

According to Emmons (1872), "... diamond fever had now attacked us all with vigor, and while day light lasted, we continued in this position picking up precious stones. That night we were full-believers in the verity of Janin's reports, and dreamed of the untold wealth that might be gathered."

King stated, "the appearance of the sandstone and country adjoining answered moderately to the description of some of the formations in Brazil and North Carolina where diamonds were known to occur."

But the next day, the group began to question the discovery, as rubies could be found in the anthills but not in soil. Sieving the dirt near the outcrop where the soil had been disturbed, rubies and a few sapphires and emeralds would be produced. But where they sieved the undisturbed soil, no gems were found.

When Table Rock was examined by the author in 1994, we could see a
series of piles of coarser gravels all in a row. These were likely
sieve piles left by the 40th Parallel Survey members as they searched for
diamonds more than a hundred years earlier. This is a photo I took of
Table Rock looking towards the foot of Diamond Peak.
On further inspection it was noticed that undisturbed anthills would not produce any rubies. But where rubies were found in other anthills, there were always nearby footprints and often a small break on the side of the anthill as if someone had pushed the rubies into the anthill with a stick.

The group began digging pits first removing the upper inch of soil, and digging down to bedrock. About 30 test pits were dug until it was concluded the gemstones did not continue below the surface. 

King and Wilson rode to Black Buttes Station and boarded the train to San Francisco. On November 10th, 1872, King contacted Henry Janin and explained their findings. Janin called an executive meeting of the company.

At the meeting, King addressed the Board of Directors of the San Francisco and New York Mining and Commercial Company. King stated, "... the new diamond fields upon which are based such large investment and such brilliant hope are utterly valueless..." King sited his evidence: 

(1) A nearly uniform numerical ratio between the rubies and diamonds; 

(2) 90% of the gems were found directly on the sandstone outcrop or an indurated crust of soil; 

(3) The gems in the soils did not continue down to bedrock; 

(4) Ruby Gulch which drained Table Rock down to Arnold Creek was found to be extremely rich in rubies at the head of the gulch, but the gemstones did not persist below the top soil level nor down the drainage; 

(5) Undisturbed soil-filled crevices on Table Rock contained no gems below the top inch of soil; 

(6) The raised portions of Table Rock contained some gems; 

(7) Field microscopic examination of sandstone samples from Table Rock contained no gemstones; 

(8) Anthills in the immediate area containing gemstones always showed
Location of the Wyoming Craton showing areas with diamond-
bearing kimberlite, lamproites and some lamprophyres. Today,
the Great Diamond Hoax site, which sits at the edge of the craton,
would be considered high-potential for diamond deposits. But
in 1872, the prospectors had no concept of cratons or favorable
geological terrains for diamonds. Cratons are the ancient cores of
artificial holes and nearby foot prints, the anthills outside the disturbed area contained no gemstones; 

(9) The variety of minerals, four types of diamonds, Oriental rubies, garnets, spinels, sapphires, emeralds, and amethysts, all occurring at one locality was thought by King to be impossible; and 

(10) Prospects were dug all around the Table Rock outside the disturbed area which produced no gemstones. 

After the Hoax. After the hoax was exposed, John Slack apparently disappeared and could not be found. It was not until after his death, that it was discovered he had moved to Arizona. 

Arnold, moved back to the safety to Elizabethtown, Kentucky. Kentucky would not extradite him to California for trial. The local sediments were expressed by one local newspaper that said, "if the two men have committed fraud, they have only been successful in out-Yankeeing the Yankees". Harpending ended up writing a book in an attempt to exonerate himself.

Map showing locations of (1) the Sybille Creek Kimberlite district,
(2) the Iron Mountain kimberlite district, (3, 4, 5, 6) the State Line diamondiferous
kimberlite district, (7) Estes Park kimberlite, and (8) Boulder Kimberlite, (9) Cortez
Creek diamond placer.
Coincidence. The location of the Great Diamond Hoax was right on the edge of an Archean Craton! Today, cratons are considered excellent terrains to search for diamondiferous kimberlite, lamproite and lamprophyre. But in 1872, this relationship was unknown. Nearly 100 years later, in 1975, diamonds were found in kimberlite only 175 miles east of the great diamond hoax site and diamonds were also found in lamprophyre 55 miles west of the great diamond hoax site - all a coincidence. In addition, hundreds of diamond indicator mineral anomalies have been identified throughout this region. This region along the edge of the Wyoming Craton is considered to have high potential for discovery of gem quality diamonds in kimberlite.

So - how do you identify a rough diamond? Its not as difficult as you think - read my blog about diamonds.


  • Hausel, W.D., and Stahl, Sandy, 1995, The great diamond hoax of 1872 (abstract): Pacific Northwest Mining and Metallurgy Conference, Bellevue, WA., p. 15.
  • Hausel, W.D., 1995, Diamond, kimberlite, lamproite, and related rocks in the United States: Exploration and Mining Geology, v. 4, no. 3, p. 243-270.
  • Hausel, W.D., 1995, Diamonds and their host rocks in the United States: Mining Engineering, v. 47, no. 8, p. 723-732.
  • Hausel, W.D., and Stahl, Sandy, 1995, The great diamond hoax of 1872: Wyoming Geological Association Resources of Southwestern Wyoming Guidebook, p. 13-27.
  • Hausel, W.D., Sutherland, W.M., and Gregory, R.W., 1995, Lamproites, diamond indicator minerals, and related anomalies in the Green River Basin, Wyoming: Wyoming Geological AssociationResources of Southwestern Wyoming Guidebook, p. 137-151.
  • McCandless, T.E., Nash, W.P., and Hausel, W.D., 1995, Mantle indicator minerals in ant mounds and conglomerates of the conglomerates of the southern Green River Basin, Wyoming: Wyoming Geological Association Resources of Southwestern Wyoming Guidebook, p. 153-163.
  • Hausel, W.D., Love, C.M., and Sutherland, W.M., 1995, Field Guide to the geology and volcanology to the Leucite Hills, Green River Basin, Wyoming: Wyoming Geological Association Road Logs to theResources of Southwestern Wyoming, p. 45-53.
  • Hausel, W.D., Marlatt, G., Neilsen, E., Gregory, R.W., 1995, Geology and hydrothermal alteration of the Quaking Asp silicified zone, Green River Basin, Wyoming: Wyoming Geological AssociationResources of Southwestern Wyoming Guidebook, p. 125-136.