Friday, June 29, 2012

It's A Diamond, Errr A Gregory?

In South Africa, a ‘Gregory’ is a term applied to a blunder of major proportions. This is all due to James Gregory, a professor from Great Britain. In the mid-1860s, many diamonds were found along the Orange River in South Africa and Professor Gregory purportedly was hired in 1868 by a London diamond dealer to investigate the Orange River diamonds to determine the potential for the region to produce diamonds. After visiting the diamond fields, Gregory published a report in the Journal of Society of Arts, stating he had made a lengthy examination of the new diamond fields and concluded there was no potential for mining diamonds as the stones that had been found had either been ‘salted’ by locals attempting to increase the value of their farms, or had been transported to the Orange River by ostriches. Apparently Gregory never considered where the diamond-laden ostriches were finding their gems. So the story goes, that within a short time, the Orange River region (its placers and kimberlites) became one of the greatest diamond producing regions in the world and produced many of the greatest diamonds ever found on earth including the giant 3,006.75 carat Cullinan diamond.

Two beautiful diamonds from Murfreesboro, Arkansas. Note
the distrinct greasy luster of the raw diamonds (photo
courtesy of Glenn Worthington).
Unfortunately, Professor Gregory will not be the last pessimist. We’ve all known exploration geologists and company CEO’s who should also have namesakes attached to blunders with Gregory in the history books. Comments like … “if there was something of value, it would have already been found”, and “we only look in elephant country” deserve a Gregory awards. Yet these types of comments are made by apparently educated people in the exploration industry every day.  Prospectors on the other hand are optimistic - sometimes overly optimistic.  An example of this optimism led to an interesting event when I was a geologist at the Wyoming Geological Survey at the University of Wyoming. 

Green octahedral diamond - a common crystal habit, although
green diamonds are not common.
I had received a phone call from an individual who thought he had found a large diamond to the west of Cheyenne. According to an unnamed gemologist from Cheyenne, this crystal was pronounced to be diamond. But the gemologist suggested that before the prospector sold all of his belongings and purchased a mansion on the French Riviera that he should visit my office for a second opinion. By this time in my career, I had been developing a reputation as a diamond exploration geologist because of my research on kimberlites and lamproites. At the end of the phone call, I gave him directions to my office. It’s about one hour’s drive from Cheyenne, so I was surprised when he and his three family members came knocking at my door about 30 minutes later, apparently anxious to cash in their millions. 

The finder of the crystal introduced himself as ‘Jack’ and did not give a last name, and without further hesitation, opened a locked brief case chained to his wrist to show me the ‘Star of Cheyenne’. It was fist size, and about the same size as the famous Cullinan diamond. The Cullinan was by far the largest diamond found in history, and was a whopping 3,006 carats, and recovered at the Premier Mine in South Africa. It was priceless and ended up in the Crown Jewels of England. I had met Dr. Arnold Waters, Jr, a few years earlier in my office. Dr. Waters was the former Chief Geologist for DeBeers in South Africa and Arnold told me that when the Cullinan was found, it had a distinct cleaved surface where part of the diamond had been broken in two during its transport to the earth's surface in a kimberlite pipe (volcano). He indicated that the other half of the diamond could have been just a large if not larger than the Cullinan itself! Where it was - was anyone's guess. Did it break off somewhere at great depth and still sitting thousands of feet deep? Did it make it to the surface and was missed by the sorters and ended up in the crusher where it made many little diamonds? 
Geologist examining rock sample with hand lens
The gem in question was gingerly handed to me. As soon as I saw it, I knew what it was, but decided to let the family down slowly, so I made a show of it. First I showed them how to test specific gravity of a mineral by weighing the gem in water then in air. I determined the crystal to have a specific gravity of 2.7 - too light for diamond (diamond's specific gravity is 3.5, heavy enough that it would show up with garnets and black sands in a gold pan). I also tested its hardness by taking a diamond chip and easily cutting a deep notch in the crystal. This resulted in an up-roar and immediate protest from the family as they thought I was scratching their priceless diamond. 

“Hold on a second,” I exclaimed.  “If this were a diamond, I wouldn’t be able to scratch it with a diamond chip so easily, diamond has a Moh’s hardness of 10 and is the hardest known mineral in nature, and it is very difficult to scratch a diamond with another diamond”.  After I calmed them down and convinced them that all they had was an ordinary piece of rock crystal (transparent massive quartz), they left the office dejected and drove back to Cheyenne with visions of mansions and Porches fading.  And I thought this was over.

The next day, I was contacted by one of our other geologists - Ray Harris (RIP) - who stopped in my office to tell me he had just received a call from a person in Cheyenne who had a probable diamond that he wanted to have verified. The person on the phone explained that he had already talked to me, but he and his gemologist decided that another opinion was necessary. 

Ray went back to his office to await the Cheyenne family. I laughed to myself. Ray was a very good geologist, but he had a reputation as a klutz. He was famous for running into things, breaking things, and if anything could go wrong – leave it up to him. One of my favorite stories about Ray took place at a staff meeting. Ray was holding a cup of coffee in his left hand and another geologist asked him for the time of day. Without hesitation, he rotated his wrist to look at his watch, pouring all of the coffee into his lap. Ray was the Jacques Clouseau of geology.

Raw uncut diamond. Note the distinct trigons (triangular growth plates on
the diamond) this is characteristic of many diamonds.
The Cheyenne family arrived with their gem. They talked about the gemologist’s opinion and their concern about my scratching their diamond. I don't know if Ray had ever seen an diamond in the rough and after examining the fist-size specimen with a hand lens, he decided to get a better look and carried it to his microscope in his adjacent lab. With the family in tow, he lost control of the sample and the specimen crashed onto the floor shattering into dozens of pieces.

The family turned white as ghosts. But Ray consoled them as he was looking down at all of the pieces. “Well, guess it wasn’t a diamond – it has conchoidal fracture”.   The family scooped up the fragments of their precious quartz and went home, never to be seen again. When Ray told me about his encounter – I laughed, and then pointed out to him that diamond (as well as quartz) also has conchoidal fracture. Ray turned white. But, I said, don't worry it was just a piece of quartz.

* This story originally appeared in an article in the ICMJ Prospecting and Mining Journal as

Hausel, W.D., 2000, Diamond Fever: International California Mining Journal, v. 69, no. 6, p. 13-15. At the time, Ray Harris was still alive and a productive member of society. However, within 6 years, he passed away after being harassed endlessly at the Wyoming State Geological Survey. It was a very sad note for a person I admired and respected. Of a very small staff of only about 26 people, 2 died, and about 40% resigned, retired or quit (all covered up by the government & press).

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