Edward C.T. Chao | |
|---|---|
| Born | November 30, 1919 (1919-11-30) |
| Died | February 3, 2008 (2008-02-04) (aged 88) |
| Alma mater | University of Chicago |
| Known for | impactmetamorphism |
| Awards | Barringer Medal(1992) |
| Scientific career | |
| Fields | Geology |
| Institutions | U.S. Geological Survey |
Edward Ching-Te Chao (趙景德; November 30, 1919 – February 3, 2008) was one of the founders of the field ofimpact metamorphism, the study of the effects ofmeteorite impacts on the Earth's crust.
Born inSuzhou,China, he was best known for discovering two high-pressure forms ofsilica in nature:coesite andstishovite.
Chao was born inSuzhou,China. He was the son of theologianT. C. Chao.[1]
Chao came to theUnited States in 1945 to teach Chinese to American troops. He then attended theUniversity of Chicago and was granted a PhD in geology in 1948. In 1949, he was employed by theUnited States Geological Survey (USGS), where he spent his entire professional career until retiring in 1994.
Chao worked on a variety of topics over the course of his USGS career, includingengineering geology,economic geology, andcoalpetrology. However, he was best known for his work onimpactgeology andtektites. Shortly after he began work on tektites in 1960, Chao was given a sample ofsandstone from the vicinity ofMeteor Crater,Arizona. From this material, he was able to isolate an unusualmineral with highrefractive index, which he showed to be a high-pressurepolymorph ofsilicon dioxide. He named the new mineralcoesite in honor of the scientist who had synthesized the same phase in the laboratory seven years earlier.[2][3] Several years later, Chao found a second high-pressure polymorph of silica in these rocks. It, too, had been previously synthesized in laboratory studies, but was not known to occur in nature. He named this mineralstishovite in honor of the person who had first made it, Russian physicist,Sergei Stishov.[4] Coesite and stishovite became known as hallmarks ofimpact crater events, which were essentially the only natural processes that produced high enoughpressures to transform ordinaryquartz into both of thesedense minerals. Chao went on to find coesite and stishovite in rocks from theRies Crater inBavaria,Germany, establishing that this structure was also produced by impact cratering.
Chao made many pioneering studies on tektites, and discovered the occurrence ofiron-nickel metal in specimens from thePhilippines. This helped establish that tektites were produced inmeteorite impacts. He also recognized that tektites showed evidence for passage through Earth's atmosphere, which led him to the conclusion that the impacts responsible for tektites occurred on theMoon, a view that is no longer widely held among scientists.
His work onMoon rocks included being a member of preliminary examination teams anda principal investigator during theApollo 11-17 research programs.
Chao received theJohn Price Wetherill Medal from theFranklin Institute and, in 1992, theBarringer Medal from theMeteoritical Society for his work in impact geology. He was a recipient of the Alexander von Humboldt Foundation Senior U.S. Scientist Award, and had an asteroid named for him,3906 Chao. The mineralchaoite, an impact-produced form ofcarbon discovered at theRies Crater, was also named in his honor.
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