Eugene Jarosewich (1926–2007): The Architect of Precision in Geochemistry
In the mid-20th century, as humanity began reaching for the stars and peering into the microscopic composition of the Earth, a fundamental problem emerged: how could scientists ensure that their measurements were actually accurate? In the world of geochemistry and meteoritics, the man who provided the answer was Eugene Jarosewich. A chemist at the Smithsonian Institution, Jarosewich became the global "gold standard" for chemical analysis, bridging the gap between classical wet chemistry and the dawning age of electron microbeam technology.
1. Biography: From Post-War Europe to the Smithsonian
Eugene Jarosewich was born on January 20, 1926, in the village of Luka, then part of Poland (now Ukraine). His early life was marked by the profound disruptions of World War II. Following the war, he lived as a displaced person in Germany, where he began his higher education at the University of Munich.
In the early 1950s, Jarosewich immigrated to the United States, seeking the stability and opportunity of the American scientific landscape. He enrolled at the University of Illinois, earning his Bachelor of Science in Chemistry in 1952. Before finding his lifelong home at the Smithsonian, he worked for several years in industrial chemistry, honing his skills in analytical techniques at companies like the Sinclair Refining Company and the Garlock Packing Company.
In 1964, Jarosewich joined the Department of Mineral Sciences at the Smithsonian’s National Museum of Natural History (NMNH). He remained there for the rest of his career, eventually becoming the head of the chemistry laboratory—a position from which he would revolutionize how we understand the composition of the solar system.
2. Major Contributions: The "Jarosewich Standards"
Jarosewich’s most significant contribution was the development of a suite of international reference standards for electron microprobe analysis (EPMA).
The Standardization Revolution:
In the 1960s and 70s, the electron microprobe became a vital tool for geologists. It allowed researchers to analyze the chemical composition of tiny spots on a mineral sample without destroying it. However, the machine required "standards"—materials of known, uniform composition—to calibrate the results.
Jarosewich realized that existing standards were often unreliable. He spent years meticulously selecting, purifying, and analyzing a set of 25 minerals and glasses. He used "wet chemistry"—a laborious, old-school method involving dissolving samples in acid—to determine their composition with a degree of precision that few others could match. These materials became known as the Smithsonian Microbeam Standards. They were distributed to thousands of laboratories worldwide, ensuring that a measurement taken in Tokyo would be identical to one taken in London or Washington, D.C.
Cosmochemistry and the Allende Meteorite:
Jarosewich was a central figure in the analysis of extraterrestrial materials. When the Allende meteorite—a massive carbonaceous chondrite—fell in Mexico in 1969, Jarosewich performed the definitive bulk chemical analysis. Because Allende is considered a "Rosetta Stone" of the early solar system, Jarosewich’s data became the benchmark against which all other primitive meteorites are measured.
3. Notable Publications
Jarosewich authored or co-authored over 100 scientific papers, but one in particular stands as a pillar of the field:
- Chemical analyses of 25 mineral standards for electron microprobe analysis (published in Geostandards Newsletter, 1980; updated in Smithsonian Contributions to the Earth Sciences, 1991). This paper is one of the most cited in the history of geochemistry, serving as the "instruction manual" for microprobe calibration.
- The Allende Meteorite Reference Sample (1970). This work established the chemical baseline for one of the most important meteorites ever studied.
- Bulk Chemical Analyses of Antarctic Meteorites, with Notes on Weathering Effects (1990). This helped scientists understand how the Antarctic environment alters the chemistry of space rocks.
4. Awards and Recognition
While Jarosewich was a humble man who preferred the laboratory to the spotlight, the scientific community recognized his contributions through several high honors:
- Jarosewichite: In 1982, a newly discovered manganese-arsenic mineral from Franklin, New Jersey, was named Jarosewichite in his honor, recognizing his contributions to mineral chemistry.
- Asteroid 4320 Jarosewich: An inner-main belt asteroid, discovered in 1981, was named after him to commemorate his work on meteorites.
- Smithsonian Exceptional Service Award: He received multiple citations for his service to the National Museum of Natural History.
- The Meteoritical Society: He was a long-standing and respected Fellow of the society.
5. Impact and Legacy
The legacy of Eugene Jarosewich is found in almost every modern geochemical laboratory. Whenever a scientist uses an electron microprobe or an ion probe to analyze a mineral, they are likely using the standards Jarosewich developed or a descendant of his methodologies.
He is often described as the "last of the great wet chemists." As the field moved toward automated, instrumental analysis, Jarosewich maintained the rigorous manual techniques that provided the necessary foundation for those new technologies. He ensured that as geochemistry became faster, it did not become less accurate.
6. Collaborations
Jarosewich was a quintessential collaborator, working with the leading lights of 20th-century geology:
- Brian Mason: A pioneer in meteoritics, Mason worked closely with Jarosewich to classify and analyze thousands of meteorites, including the first samples returned from the Moon by the Apollo missions.
- Edward Henderson: Jarosewich worked with Henderson at the Smithsonian to curate and expand the National Meteorite Collection.
- Klaus Keil: A co-author on many papers, Keil and Jarosewich collaborated on the development of microprobe techniques that defined the field of cosmochemistry.
7. Lesser-Known Facts
- The "Jarosewich Accuracy": Among his colleagues, "Jarosewich accuracy" was a slang term for a measurement that was beyond reproach. He was famous for repeating an analysis dozens of times if the "sum" of the elements did not equal exactly 100.00%.
- Apollo 11: Jarosewich was among the select group of scientists entrusted to analyze the first lunar samples brought back by Neil Armstrong and Buzz Aldrin. His work helped confirm that the Moon was chemically distinct from the Earth, lacking volatile elements.
- A Lifelong Mentor: Despite his stature, Jarosewich was known for his patience with students and visiting researchers, often spending hours teaching them the delicate art of sample preparation.