Steven B Shirey

✦ These types of rough diamonds, besides being the world's most valuable gemstones based on size and clarity, are remarkable for geological reasons.  Research done at the Gemological Institute of America by Evan Smith and the Carnegie Institution for Science by Steve Shirey, Peng Ni, Anat Shahar, Emma Bullock, and Jianhua Wang shows them to crystallize in the mantle transition zone (440-660 km deep) and to carry metallic inclusions. The iron in the inclusions was derived from magnetite and awaruite crystallized during serpentinization of peridotite on the ocean floor before being carried to great depth by subduction. See: Smith, E.M., Peng, N., Shirey, S.B., Richardson, SH., Wang, W., and Shahar, A. (2021) Heavy iron in large gem diamonds traces deep subduction of serpentinized ocean floor. Science Advances 7: eabe9773 https://doi.org/10.1126/sciadv.abe9773

Photo above is by Robert Weldon. © 2015 GIA. Courtesy of Gem Diamonds Ltd. This group of type IIa rough diamonds (VRL# 190894) shown here range from 14 to 91 carats and sometimes appear to be broken fragments of once larger diamonds. 

Interests and education

Geologist and isotope geochemist Steven Shirey retired in June 2026 after 42 years as a scientific staff member of the Geochemistry and Cosmochemistry Group of the Earth and Planets Laboratory (EPL) at the Carnegie Institution for Science. Steve has moved to an emeritus position, continues to do science, and takes on a new role as one of the institution's three ombuds.  

Steve's main interests are diamonds as the deepest probe of plate tectonics, the igneous evolution of the Earth, and the emergence of Earth's continents. Steve's career as a geologist has covered the time from just after the acceptance of plate tectonics through its maturation which has allowed him to work on a large number of interesting areas in geology and geochemistry. Over his career Steve has advised about 39 postdoctoral fellows and 26 PhD students who have gone on to successful careers as university professors or in industry.  

Steve is a Fellow of the American Geophysical Union (AGU), the Geochemical Society, the Geological Society of America, and the Mineralogical Society of America (MSA). He was 96th President of MSA and the 100th President of the Geological Society of Washington. He is the recipient the 2025 Harry H. Hess Medal, given by AGU "In recognition of seminal contributions in geochemistry and mantle petrology and the origin, evolution, and consequences of plate tectonics on Earth".  See the Carnegie press release here. Steve was recently named as one of the AGU College of Fellows Distinguished Lecturers for 2026-2027.

Steve was educated at these institutions:

Dartmouth College, Hanover, NH: BA, Geology (1972)

University of Massachusetts Amherst, MA: MS, Geology (1975) 

Stony Brook University, Stony Brook, NY: PhD, Geochemistry (1984)

Carnegie Institution for Science, Washington, DC: Postdoctoral Fellow, Isotope Geochemistry (1984-1985) 

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Home institution

The Earth and Planets Laboratory (EPL) is one of the three divisions that make up the Carnegie Institution for Science —the nation's oldest, privately-endowed, research organization dedicated to fundamental scientific research for the benefit of mankind. The EPL (established 2019) is a combination of the former Geophysical Laboratory (established 1904) and the Department of Terrestrial Magnetism (established 1902). 

At EPL, research in geophysics, seismology, volcanology, geochemistry, cosmochemistry, astronomy, planetary science, experimental petrology, mineral physics, and material science is carried out on one campus in residential northwest Washington, DC by ~50 resident scientists (25 staff scientists and 25 postdoctoral fellows). 

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Research environment

The geochemists and cosmochemists of EPL where Steve works are historians of the evolution of Earth and the Solar System over the last ~4.6 billion years with a long record of making novel discoveries. Our thermal ionization, secondary ion, and inductively-coupled plasma mass spectrometers permit isotope ratio measurements at today’s limits of sensitivity, precision, and accuracy. They are an ensemble of tools whose powers are trained on solid Earth samples and tiny remnants of the Solar System delivered by meteorites and asteroid missions. 

Collectively, these instruments are a type of planetary observatory that operates much like an astronomical observatory does in that both observatories are “time machines”, to be aimed at and focused on a wide array of scientific problems. EPL's mass spectrometers allow looking back in geologic time to earlier Eras in Earth history and back beyond Earth’s creation to quantify ancient geological and cosmological processes. The possible science is limited only by the imagination as to the targets chosen and the questions posed.