Experts on Point is a University Communications series focusing on CMU faculty who have special insights into interesting, important and timely topics. See the complete series here.
The annual Orionid meteor shower is about to grace the heavens with up to 20 "shooting stars" an hour Oct. 20-21.
Hardly a week goes by without meteors or meteorites (meteors that hit the ground) making the news somewhere. In October 2018, it was Central Michigan University's turn in the spotlight after Mona Sirbescu, a geology faculty member in Earth and Atmospheric Sciences, identified a man's 22-pound iron doorstop as the sixth-largest meteorite ever found in Michigan.
Mona Sirbescu examines the Edmore meteorite in 2018.
We spoke with Sirbescu about life after meteorite stardom, earth science and the glowing mineral known in Michigan as "yooperlite."
Other than by showing it to you, how can someone help determine whether a rock is a meteorite?
A: People can start with step-by-step characterization of their material, using online resources such as this one from the Lunar and Planetary Science Laboratory, University of Arizona. High-resolution photographs or videoclips, including some detailed close-ups, can help me sort out the inevitable "not a meteorite." I ask for additional information or a fragment if I have any doubt of the nature of the material.
Have you confirmed or debunked any purported meteorites since 2018?
A: Yes! Several inquiries per week continue to pour in. I have worked with a few hundred "meteor-wrongs" sent as photos or shipped/brought to me. But I have also received two real meteorites. One was sent from Kenya, Africa, and I concluded it was a fragment from the recently discovered Sericho pallasite meteorite, based on its appearance and composition. The fragment was donated by the owner and it is now in the CMU meteorite collection.
The other is a small sample from an iron-nickel meteorite brought to me, which is currently being processed in Dr. Anthony Chappaz's STARLAB (short for Speciation-Traces-Analysis-Radioisotopes Lab) for trace-element fingerprinting to determine what meteorite it belongs to.
I have a new 27-gram fragment that appears to be a stony meteorite found near Edmore — again! It was brought to me just recently, so we are at very early stage of investigation.
What can you tell us about yooperlite?
A: It's a colloquial rock name created in the Upper Peninsula, although this type of rock is found in many other places in the world. The name yooperlite went viral. Nothing wrong with a little regional bragging, right?
While it is a common-looking igneous rock in plain light, spots that glow an unusual bright orange appear under ultraviolet light (black light). Pebbles of yooperlite were discovered in 2017 along Lake Superior beaches. Searching for yooperlite has become a very trendy nocturnal hobby for many beachcombing enthusiasts. I have my own collection gathered in one short trip this summer.
The UV fluorescent spots in the yooperlite pebbles are the first mineralogical occurrence of the mineral sodalite in the state of Michigan. Notably, the pebbles were brought by glaciers from Ontario. However, I suspect that multiple minerals may cause the fluorescence in these rocks.
Geology and earth science play a part in many aspects of science and life, such as fossil fuel exploration and geothermal energy. What are some other examples?
A: Let's not forget exploration and sustainable mining of mineral resources. In particular, critical minerals that are quite rare but are vital for modern "green" technologies and nonconventional energy industries.
You can't have wind turbines without several tons of copper and tens of pounds of rare earth elements. Batteries for electric cars and electricity storage require lithium, nickel and cadmium. Solar panels need even rarer metals such as indium, neodymium or praseodymium. But ironically, it takes huge amounts of fossil fuel to dig these rare metals out of the ground — and that is not progress. We need to look for sustainable ways to mine Earth resources.
Geologists and geochemists figure out the geologic origins of ore deposits that contain these metals at mineable concentrations. They use this knowledge to explore and find new mineral resources. They also characterize the existing mineral ores with ever-improving analytical methods.
What would you say is the most interesting fact about geology or about rocks and minerals?
A: Geology may sound like an antique science, and some prefer to call it geoscience. But no matter what you call it, this complex, highly interdisciplinary science has always supported and continues to support civilization's needs, both practical and theoretical.
Water, energy, minerals, keeping us safe from natural hazards, the origins of life, solar system evolution, remediating the environment — you name it; it's all within the realm of geology.
About the expert
Mona Sirbescu has taught geology courses in earth processes, mineralogy, petrology, economic geology and more since joining CMU in 2001. She earned her Bachelor of Science degree in geological engineering from the University of Bucharest, Romania; her master's degree from Binghamton University, New York; and her Ph.D. from the University of Missouri-Columbia. She recently attended the oath of allegiance ceremony and has become an American citizen.