Edward Ching-Te Chao (; November 30, 1919 – February 3, 2008) was one of the founders of the field of impact metamorphism, the study of the effects of meteorite impacts on the Earth's crust. Born in Suzhou, China, he was best known for discovering two high-pressure forms of

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...

in nature:

coesite Coesite is a form ( polymorph) of silicon dioxide Si O2 that is formed when very high pressure (2–3 gigapascals), and moderately high temperature (), are applied to quartz. Coesite was first synthesized by Loring Coes Jr., a chemist at the ...

and stishovite.

Early life

Chao was born in Suzhou, China. He was the son of theologian T. C. Chao.

Career

Chao came to the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

in 1945 to teach Chinese to American troops. He then attended the

University of Chicago The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private university, private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park, Chicago, Hyde Park neighborhood. The University of Chic ...

and was granted a PhD in geology in 1948. In 1949, he was employed by the

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

(USGS), where he spent his entire professional career until retiring in 1994.

Scientific contributions

Chao worked on a variety of topics over the course of his USGS career, including

engineering geology Engineering geology is the application of geology to engineering study for the purpose of assuring that the geological factors regarding the location, design, construction, operation and maintenance of engineering works are recognized and accou ...

, economic geology, and

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when ...

petrology. However, he was best known for his work on

impact Impact may refer to: * Impact (mechanics), a high force or shock (mechanics) over a short time period * Impact, Texas, a town in Taylor County, Texas, US Science and technology * Impact crater, a meteor crater caused by an impact event * Impac ...

geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ea ...

and

tektite Tektites (from grc, τηκτός , meaning 'molten') are gravel-sized bodies composed of black, green, brown or grey natural glass formed from terrestrial debris ejected during meteorite impacts. The term was coined by Austrian geologist Franz ...

s. Shortly after he began work on tektites in 1960, Chao was given a sample of

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

from the vicinity of

Meteor Crater Meteor Crater, or Barringer Crater, is a meteorite impact crater about east of Flagstaff and west of Winslow in the desert of northern Arizona, United States. The site had several earlier names, and fragments of the meteorite are officia ...

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

. From this material, he was able to isolate an unusual

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...

with high

refractive index In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

, which he showed to be a high-pressure polymorph of

silicon dioxide Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...

. He named the new mineral

in honor of the scientist who had synthesized the same phase in the laboratory seven years earlier. 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 mineral stishovite in honor of the person who had first made it, Russian physicist, Sergei Stishov.Chao, E.C.T. et al. (1962), Stishovite, a very high pressure new mineral from Meteor Crater, AZ, Journal of Geophysical Research: 67: 419-421. Coesite and stishovite became known as hallmarks of

impact crater An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact crater ...

events, which were essentially the only natural processes that produced high enough

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...

s to transform ordinary

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

into both of these

dense Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematically ...

minerals. Chao went on to find coesite and stishovite in rocks from the Ries Crater in

Bavaria Bavaria ( ; ), officially the Free State of Bavaria (german: Freistaat Bayern, link=no ), is a state in the south-east of Germany. With an area of , Bavaria is the largest German state by land area, comprising roughly a fifth of the total lan ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

, establishing that this structure was also produced by impact cratering. Chao made many pioneering studies on tektites, and discovered the occurrence of

iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow ...

metal in specimens from the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

. This helped establish that tektites were produced in meteorite 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 the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

, a view that is no longer widely held among scientists. His work on

Moon rocks Moon rock or lunar rock is rock originating from Earth's Moon. This includes lunar material collected during the course of human exploration of the Moon, and rock that has been ejected naturally from the Moon's surface and landed on Earth as ...

included being a member of preliminary examination teams and a principal investigator during the

Apollo Apollo, grc, Ἀπόλλωνος, Apóllōnos, label=genitive , ; , grc-dor, Ἀπέλλων, Apéllōn, ; grc, Ἀπείλων, Apeílōn, label= Arcadocypriot Greek, ; grc-aeo, Ἄπλουν, Áploun, la, Apollō, la, Apollinis, label ...

11-17 research programs.

Publications

*
Comparative water-quality assessment of the Hai He River basin in the People's Republic of China and three similar basins in the United States
''

U.S. Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and ...

Professional Paper No. 1647 (2001) *
Comparison of the Cretaceous-Tertiary boundary impact events and the 0.77-Ma Australasian tektite event; relevance to mass extinction
''

Bulletin No. 2050 (1993) * ''Allocation of subsamples of Apollo 17 lunar rocks from the boulder at station 7, for study by the International Consortium''

Open-File Report No. 78-511 (1978) *
Merumite; a complex assemblage of chromium minerals from Guyana
'

Professional Paper No. 887 (1976)

Honors

Chao received the

John Price Wetherill Medal The John Price Wetherill Medal was an award of the Franklin Institute. It was established with a bequest given by the family of John Price Wetherill (1844–1906) on April 3, 1917. On June 10, 1925, the Board of Managers voted to create a silver ...

from the

Franklin Institute The Franklin Institute is a science museum and the center of science education and research in Philadelphia, Pennsylvania. It is named after the American scientist and statesman Benjamin Franklin. It houses the Benjamin Franklin National Memori ...

and, in 1992, the Barringer Medal from the

Meteoritical Society The Meteoritical Society is a non-profit scholarly organization founded in 1933 to promote research and education in planetary science with emphasis on studies of meteorites and other extraterrestrial materials that further our understanding of the ...

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 mineral chaoite, an impact-produced form of

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...

discovered at the Ries Crater, was also named in his honor.

References

External links

''Washington Post'' obituaryMeteoritical Society
{{DEFAULTSORT:Chao, Edward C. T. 1919 births 2008 deaths Republic of China (1912–1949) emigrants to the United States University of Chicago alumni Planetary scientists 20th-century American geologists United States Geological Survey personnel Barringer Medal winners