Edward Chao, 88; a Rock Star of Geology

Edward Chao helped advance the study of the Earth's mantle.
Edward Chao helped advance the study of the Earth's mantle. (Family Photo - Family Photo)
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By Patricia Sullivan
Washington Post Staff Writer
Saturday, February 9, 2008

Edward Ching-Te Chao, 88, a geologist with the U.S. Geological Survey for 45 years whose identification of two dense forms of minerals in nature paved the way for scientists to understand the structure of the Earth's mantle, died of congestive heart failure Feb. 3 at his home in Fairfax County.

Dr. Chao studied a variety of substances, including minerals of the Meteor Crater in Arizona, rocks in the Ries Crater in southwestern Germany, ore deposits in Inner Mongolia and moon rocks that astronauts recovered in the late 1960s.

He was the first person to recognize two high-pressure forms of silica in nature: coesite and stishovite. (The latter had first been synthesized in a laboratory in the Soviet Union.) For this work, Dr. Chao was awarded the Wetherill Medal of the Franklin Institute in 1965.

The identification and description of both minerals was "a really huge discovery for this field of high-pressure minerology and had very important implications for geophysics," said Russell J. Hemley, director of the Geophysical Laboratory at the Carnegie Institution of Washington.

The discovery of those minerals, found beneath the Earth but never before seen on its surface, helped scientists understand the role that meteors play in the formation of the planet.

"He founded the field of impact metamorphism," said Ahmed El Goresy, professor of cosmochemistry at the University of Bayreuth in Germany. "This is his own child. It has become a very big business in science."

More of a practical scientist than a theorist, Dr. Chao was known for his field work and meticulous collection of evidence and documentation.

"I've been involved in controversial studies during my whole career," Dr. Chao told the Reston Times newspaper in 1992 after an asteroid was named for him. "People don't believe, but you do your hard work. It takes time to gradually convince them. You always have to find new, better evidence."

Goresy, who was at the lecture in which Dr. Chao reported that the Ries Crater, thought to be volcanic, was born 15 million years ago when a meteor struck the Earth. "It was, in fact, a shock for all of us," Goresy said. "I still remember . . . a German scientist stood up and said: 'I have been working on Ries my entire career, for 30 years, and have turned over every rock. Here comes an American who's been there two days.' . . . [Dr. Chao] said 'Here is the evidence.' "

Dr. Chao was born in Suzhou, China, and moved to the United States in 1945 to teach Chinese to U.S. troops. When World War II ended, he graduated from the University of Chicago and received a doctoral degree in geology there in 1948.

He moved to Alexandria to work for the Geological Survey, where he stayed until he retired in 1994. He began in military geology, then transferred to the survey's branch of geochemistry and petrology, where his investigations focused on identifying new minerals in the Green River Formation and the abundance of zirconium in igneous rocks. Petrology is the branch of geology that deals with the classification, location, composition, structure and origin of rocks.

He also published a comprehensive geological field guide describing outcrops in the Ries Crater.

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