Finding Diamonds, Gemstones and Gold

The Schaffer 15 diamondiferous kimberlite in foreground with exposed blue-ground in badger hole diggings. The entire open (treeless) park is underlain by
kimberlite.

“Always do what is right. It will gratify half of mankind and astound the other.” - Mark Twain

In 1977, I was privileged to map the State Line diamond district south of Laramie. I could never thank Dr. Dan Miller (RIP) enough for that opportunity. Dr. Miller was an outstanding person and director of the Wyoming Geological Survey located at UW in Laramie, and he decided I was the best candidate for the position of minerals research geologist, even though I didn't have much experience and just barely started shaving. 

As a young geologist who specialized in igneous rocks, metamorphic rocks, and mineral deposits, this was a dream come true. Diamond deposits are rare and found primarily associated with a host rock known as kimberlite. Such a rare igneous rock filled with diamonds, other gems such as chromian-diopside and -enstatite, with pyrope-, spessartine-, and almandine-garnet, other rare minerals and some of the rarest mantle and crustal nodules along with unusual chemistry and weird emplacement mechanics - such rocks were a geologist's dream with my background. For example, picture a geologist jumping up and down, hopping from rock to rock while singing "Lucy in the Sky with Diamonds". Yep, the ranchers thought I had lost my mind, but I was happy.

General map showing locations of the State Line and Iron Mountain kimberlite districts and nearby
kimberlites, lamproites and diamond-indicator mineral anomalies.

While mapping during the fall of 1977 and summer of 1978, I was able to add to the number of diamond deposits that had been previously discovered in the district by David Eggler, Chuck Mabarak and Mac McCallum - all excellent geologists. I was an amateur among giants running around cattle pastures watching out for ticks, unfriendly ranchers, and badgers who loved to dig in the soft, weathered, blue-ground kimberlite when not trying to eat geologists. Luckily, I did not see any rattlesnakes in this area - not like the hundreds that harassed me daily at the Iron Mountain kimberlite district I mapped years later.

Schaffer 3, elongated diamondiferous kimberlite pipe in the Colorado-Wyoming State Line district.
Where? This is one of the more obvious pipes (actually, this should be called a 'blow', or
an elongated kimberlite along a narrower dike. Such pipes usually are circular, but start to narrow 
down in the earth to linear blows until reaching a feeder dike at 3 thousand feet deep. So, based on
morphology of this pipe and texture of the rock under the soil, this pipe probably lost about
half of its upper structure during erosion over the past 400 million years. Just think, half
of its diamond content was freed from the rock and carried down-slope and down stream.
The geography suggests there must be a cache of detrital diamonds in the adjacent drainages in
Wyoming continuing down into Colorado. Oh yea, the pipe is the open park (treeless) with a
visible grassy vegetation anomaly.

I really enjoyed mapping the State Line district while educating myself on characteristics of diamond deposits. My work, education, mistakes and successes provided a foundation for future work on other diamond and colored gemstone deposits while working in research at the Wyoming Geological Survey at UW, as a consultant for mining companies, and VP of US Exploration for DiamonEx Ltd. For me, I was living a dream job.

While mapping, I would walk along elongated kimberlite pipes. The pipes followed distinct trends, so, I simply followed the known kimberlite elongations based on the presence of a thick (for Wyoming) stands of blue grass in carbonate-rich soil (these magmas erupt with considerable release of CO2 gas  into the atmosphere - so much so that it is believed the gaseous eruption temperature of the expanding gas is zero degrees centigrade). So, if you personally witnessed the eruption of a kimberlite volcano, your eyebrows likely would fall off because of frostbite. So, for those who love global warming - just think of all of the nasty CO2 being released into our atmosphere to assist in growth and health of trees.

Thus, while walking along trends, I would search for any kind of anomaly, such as high grass, light-blue to gray soil (known as blue-ground), diamond indicator minerals, mantle nodules brought up by the kimberlite, rounded cobbles polished by kimberlite magma, and rarely actual kimberlite rock. To help find kimberlite, diamond exploration geologists carry loupes around their neck so they can examine minerals, rocks and soil with 10x to 15x magnifiers, and a small plastic bottle of dilute hydrochloric acid to squirt on suspicious soil to see if it reacts with acid. The reaction produces a lot of CO2 (same stuff you find in soda pop). 

Trenching the Aultman 1 diamondiferous kimberlite, Colorado-Wyoming state line district. Blue-
ground exposed in backhoe trench after starting in the reddish brown granitic soil.

Later, after receiving a grant from the US Bureau of Mines to search for kimberlite, I purchased badly needed geophysical equipment for the Wyoming Geological Survey including electromagnetic, magnetic, resistivity and seismic units and with these, myself and my contract geologists further detected hidden kimberlites and dikes in the district.  

At about the same time the geophysical  surveys were completed, Cominco-American was granted a special permit to explore the property in Wyoming for diamonds. They set up a diamond extraction mill at a sand and gravel pit along the northern edge of Ft. Collins, Colorado adjacent to highway 287, and hauled the diamondiferous material from the pipes along the state line to Ft. Collins for processing. Several diamonds were recovered, but there were reports of problems with the bulk sampling mill. Unfortunately, not enough diamonds were recovered, and after a time, the operation ceased. This was pre-Biden, a time of peace, little inflation, reasonable gas prices, fewer criminals in Congress, and  lower diamond values. The calculated ore grades from minimal sampling suggested that these kimberlites were likely not commercial; however, kimberlites at Kelsey Lake and the Sloan ranch in Colorado, had much better grades and highly quality diamonds.

After this project, mineral discoveries became an annual event. Predicted in a book, co-authored with  Wayne Sutherland, we suggested a significant iolite gem deposit was likely to occur in the Grizzly Creek area to the north, in the Central Laramie Mountains based on similar geology to the Palmer Canyon deposit. And then, more and more gems were found over the years giving Wyoming the distinction of have the greatest number of known gem deposits of any state in the US, and the most diversified variety of gemstones (Hausel, 2014).

I would still be in Wyoming finding new gem and gold deposits, but it was not in the stars. The new director of the Survey ethically-challenged with an innate hatred for all productive, free-thinking, independent employees who hated the 1st amendment of the constitution. With no place for independence, creativity, free speech it was sadly time for me to move on and leave my home of more than 30 years. 

“A clear conscience is the sure sign of a bad memory.” - Mark Twain