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 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
Stishovite is an extremely hard, dense tetragonal form ( polymorph) of silicon dioxide. It is very rare on the Earth's surface; however, it may be a predominant form of silicon dioxide in the Earth, especially in the lower mantle.
Stishovite ...
.
Early life
Chao was born in
Suzhou,
China. He was the son of theologian
T. C. Chao
Tzu-ch'en Chao (; 1888–1979), also known as T. C. Chao, was one of the leading Protestant theological thinkers in China in the early twentieth century.
Life
Chao was born on February 14, 1888, in Xinshi, Deqing County, Zhejiang, China. ...
.
Career
Chao came to the
United States in 1945 to teach Chinese to American troops. He then attended the
University of Chicago and was granted a PhD in geology in 1948. In 1949, he was employed by the
United States Geological Survey (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 acc ...
,
economic geology
Economic geology is concerned with earth materials that can be used for economic and/or industrial purposes. These materials include precious and base metals, nonmetallic minerals and construction-grade stone. Economic geology is a subdisciplin ...
, 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 dead ...
petrology
Petrology () is the branch of geology that studies rock (geology), rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly ...
. 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
* Imp ...
geology 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 Fran ...
s. Shortly after he began work on tektites in 1960, Chao was given a sample of
sandstone 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 offi ...
,
Arizona. From this material, he was able to isolate an unusual
mineral with high
refractive index, which he showed to be a high-pressure
polymorph of
silicon dioxide. He named the new mineral
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 ...
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
Stishovite is an extremely hard, dense tetragonal form ( polymorph) of silicon dioxide. It is very rare on the Earth's surface; however, it may be a predominant form of silicon dioxide in the Earth, especially in the lower mantle.
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 events, which were essentially the only natural processes that produced high enough
pressures to transform ordinary
quartz 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. Mathematicall ...
minerals. Chao went on to find coesite and stishovite in rocks from the
Ries Crater Ries is the German word for a unit of paper ream, derived from the Arabic word ''rizma''.
The term can refer to:
Geography
* Nördlinger Ries, a large circular depression in western Bavaria, Germany.
* Ries (Graz), a district of the city of Gra ...
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, establishing that this structure was also produced by impact cratering.
Chao made many pioneering studies on tektites, and discovered the occurrence of
iron-
nickel metal in specimens from the
Philippines. 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, 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, a ...
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''
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, a ...
Bulletin No. 2050 (1993)
* ''Allocation of subsamples of Apollo 17 lunar rocks from the boulder at station 7, for study by the International Consortium''
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, a ...
Open-File Report No. 78-511 (1978)
*
Merumite; a complex assemblage of chromium minerals from Guyana'
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, a ...
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 silve ...
from the
Franklin Institute and, in 1992, the
Barringer Medal
The Barringer Medal recognizes outstanding work in the field of impact cratering and/or work that has led to a better understanding of impact phenomena. The Barringer Medal and Award were established to honor the memory of D. Moreau Barringer Sr. ...
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
Chaoite, or white carbon, is a mineral described as an allotrope of carbon whose existence is disputed. It was discovered in shock-fused graphite gneiss from the Ries crater in Bavaria. It has been described as slightly harder than graphite, with ...
, an impact-produced form of
carbon discovered at the
Ries Crater Ries is the German word for a unit of paper ream, derived from the Arabic word ''rizma''.
The term can refer to:
Geography
* Nördlinger Ries, a large circular depression in western Bavaria, Germany.
* Ries (Graz), a district of the city of Gra ...
, 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