Drew Barkoff: Friend of The Book

Drew Barkoff is a Ph.D. student at the University of Nevada in Las Vegas. He has been extremely helpful in all of my conversations with him, tolerating the questions of an unschooled writer. In his own words he describes some of the geological journey he has taken so far . . .

As for what part of the American Southwest interests me the most, the truth is all of it. Learning geology in NJ (effectively a massive sandbar) made me long for mountains and actual rock outcrops that weren’t a multiple-hour drive away. People living in the SW are geologically spoiled whether they know it or not, but I would argue that the Las Vegas, Nevada region is as good as it gets.

The LV region is centered between the Colorado Plateau and the Sierra Nevada, and situated within the Basin and Range province. This means that we have access to not only to rocks from a very wide range of earth’s history, but a number of different tectonic environments as well, ranging from the high-grade metamorphics of the coast belt in CA, to the middle- and upper- crustal sedimentary rocks in NV, to the igneous- and metamorphic core complex-rich rocks of Southern UT. Additionally, NV is the #1 state for mining, highlighting the fact that NV has some of the best mineralization in the county.

As for how I got interested in geology, it was a long-time coming. I have always been interested in the sciences, and chemistry in particular, something about how the complexities and processes of the natural world can all be described in a very ordered, logical manner through chemistry really appealed to me, it is the link that brings all the other sciences together.

When I first went to college, I thought I knew what I wanted to do for a career, and started my undergraduate Biology degree at Ursinus College, a small school in central PA. Within about a year, I realized that I was struggling and not enjoying the material at all, so I decided to search for another major in another field I was interested in. That summer, I took three classes at the local community college that interested me: Business and Economics, History, and Geology, with the goal of going the direction of whichever class I liked best for my new major. Needless to say, the geology class blew the others out of the water and I enrolled at another local school that Fall, Stockton University in NJ, and started my geology undergraduate degree.

My grades went from straight C’s and B’s to straight A’s, with seemingly little hard work, because I loved it that much. During my Junior year, my professor, Matthew Severs, asked me if I was interested in taking part in a research project, without thinking too much, I said yes. This critical moment is what changed the course of my life and academic career, and I am very grateful to Prof. Severs for the opportunity and seeing my potential. My research project involved determining the temperatures and pressures of pegmatite formation at the Oxford Pegmatite Field, Oxford Co., ME, using fluid inclusion thermobarometry, as well as determining the petrogenetic order of pegmatite formation.

Pegmatites, being some of the most spectacular sources for mineral collecting, really got me interested in the geochemistry behind their formation and what processes are capable of enriching them in many rare metals such as Be, Li, U, etc.. This project was successful and I felt confident enough in my research capabilities that I applied for a number of graduate schools during my senior year.

I was accepted to start a Master’s project at the University of Arizona, under Prof. Matthew Steele-MacInnis in the economic geology program. My Masters project focused on further developing a novel technique of using internal pressures developed by trapped mineral inclusions during cooling and exhumation to back-calculate the pressures and temperatures of formation. This method requires using Raman spectroscopy to quantify the internal pressures of the mineral inclusions (Raman peak location of different bonds are pressure-dependent) which can be used in combination with the compositionally-determined physical properties of the mineral phases involved to determine possible P-T conditions that may have produced their rocks, also using field relation constraints.

I loved the heavily analytical nature of this study but being in the Economic Geology department exposed me to the type of work the other students were working on, and needless to say, that interested me too. I knew I wanted to go in the direction of economic geology next because they are the ultimate example of crustal geochemical anomalies, so I applied to a few programs across the US and Canada that offer this program and I was lucky enough to be accepted to start my Ph.D. at the University of Nevada Las Vegas, under Prof. Simon Jowitt. Currently at UNLV, I am working on gaining a better understanding of the petrogenesis of evolved, topaz-bearing rhyolites in SW UT and their economic potential to be low grade, high tonnage resources of many rare metals such as the REE, Be, Li, and U.

As for what classes aspiring geologist can take to quickly gain a better understanding of geology, I would suggest physical geology (101 level class, might be too basic) and especially mineralogy and igneous petrology. Mineralogy gives you a very good (probably over the top for most people) understanding of mienrals, how they are constructed and the effect this has on what elements can make up their structures. Igneous petrology is a 2nd or 3rd year course but is easily understandable by anyone with a physical geology-level understanding. Igneous petrology really focuses on how crustal or mantle magmas form and how their evolution affects the geochemistry of these rocks. I think it best to start with igneous processes, then potentially moving onto sedimentary. And metamoprphic petrology because igneous petrology is the most applicable to most types of rocks, but classes exist for whatever your specific interest may be.

Regarding the fluorescent minerals, I don’t know too much about them specifically but many minerals can be UV fluorescent and it really depends on the formation conditions, and more importantly, geochemistry of the fluids that formed them. From what I know, the energy of the UV light is enough to excite certain transition metals within the mineral structure to jump to a higher energy state and then instantaneously dump this energy in the form of light as the electrons try to reach equilibrium again. I can actually look into some research on this if you would like an even more scientific explanation, this is quick-and-dirty explantion.

~Drew Barkoff

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Picture Sandstone: Common and Extraordinary

Rockhounds should look for anything special, not necessarily what they first start out searching for. An intense gold interest may blind a person to something common yet wonderful, right under their feet. Sedimentary rocks and their related formations are a good example.

Erik Christiansen and Kenneth Hamblin say that a rock formation is,  “A distinctive body of rock that serves as a convenient unit for study and mapping.” The USGS goes a bit further, writing that, “A rock formation is a body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it.”  Sedimentary rocks are usually named for the formation they were found in. There are hundreds of sedimentary based formations.

To serve as an example of a sedimentary rock and its related formation for my book, I bought the treated sandstone you see pictured below. It’s about three inches by five. It shows what can be done with a common rock, transforming it into something that rivals fine wood grain in its beauty. Being sandstone, it was assuredly easy to slab it with a rock saw into a square.

The seller’s description reads as follows:

“This is natural sandstone that formed 180 to 220 million years ago by wind and water as part of the geological formation ‘Shinarump.’ The colors and design were induced by a mineral spring containing iron oxides. If you like the unusual and beautiful works of nature, you will enjoy this picture sandstone product. Truly ‘Nature’s most beautiful painting.’ This piece comes from northern Arizona. The design and patterns are natural, its color is achieved by heat treating the stone. This caused the iron oxides found naturally in the stone to react, the richer the iron the deeper the color.”

Wikipedia has this good introduction to the Shinarump conglomerate, which is found throughout the Colorado plateau. You can read it by clicking here.