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(left
to right)
John Freeman
Jill Dill Pasteris ’74
Brigitte Wopenka
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Pulling
It All Together
by Dorothy Wright
When Jill Dill Pasteris ’74
studies a rock or mineral, she is reading the
synopsis of a complex story that pulls together
elements from biology, chemistry, physics and
mathematics. A professor of earth and planetary
sciences at Washington University in St. Louis,
Pasteris explains, "An incredible sense of
time and cycles is captured by rocks. The study
of earth science is a powerful way to bring together
what otherwise might have seemed disjointed facts."
It is a lesson she learned
well from her geology teachers at Bryn Mawr. "Professor
Weecha Crawford was great at conveying that lesson,"
Pasteris recalls. "We’d be studying
factual information, and then on a homework assignment
or exam, she’d pose a question that would
ask us to pull it all together.
"This pulling process
could be painful," Pasteris says, laughing,
"But I have realized that there is a higher-order
understanding in addition to all the factual information.
For me that’s really the power of science."
Over the years, Pasteris’
interest in discovering how things come together
has led her to cross the boundaries between the
sciences. An economic geologist (one who studies
ore deposits), Pasteris takes a mineralogic-geologic
approach to studying both traditional and nontraditional
materials — from fluid inclusions in minerals
and glasses to nanocrystalline precipitates and
biological minerals in bacteria and humans.
Pebbles
in Her Pockets
Pasteris was captivated by
earth science at an early age. "I was always
fascinated with rocks," she recalls. "My
mother would complain that when she’d go
to throw my clothes in the washer, the pockets
would be full of pebbles."
Her ninth-grade geology class
intensified her interest. "We went on a field
trip to a boulder field," Pasteris says.
"I was so excited! It was just amazing to
find all these rocks wherever I looked!"
She says her family knew she would become a geologist
even before she announced her intentions one day.
"They said, ‘Sure, what else would you
be?’"
When Pasteris was searching
for a college, she discovered Bryn Mawr. "That
was the place for me," she says. "Of
course I knew I wanted to be a geology major and
ended up taking a huge number of courses. Professors
Weecha and Bill Crawford were my mentors, and
all of my professors were great."
Pasteris recalls taking an
introductory geology class with Edward Watson.
"He was from the old school," she says.
"He would come in to lecture with his suit
on underneath his white lab coat — the quintessential
scientist. He had marvelous stories to tell about
his experiences as an expert witness on quarrying."
For her senior project, Pasteris
studied the formation of very old marbles —
which are calcium carbonate rocks — collected
from local outcrops. "The other day I opened
an old book and out popped a letter from Weecha
Crawford identifying me as a Bryn Mawr geology
student. I carried it around in the field so that
when I knocked on people’s doors to ask if
I could walk across their fields to look for marble
outcrops, they wouldn’t think I was loony!"
A
Bold Idea
A 1974 Fulbright Scholarship
took Pasteris to the University of Heidelberg,
Germany, where she studied ore-deposit rocks.
The next year she began her Ph.D. work at Yale.
"I became intrigued with the tiny inclusions
of fluid within minerals. That was not part of
my thesis, but I kept it in the back of my mind."
After completing her doctoral
degree at Yale in 1980, Pasteris joined the faculty
of Washington University, where she pursued the
study of fluid inclusions. "Some of the most
important past and ongoing geologic processes
are chemical reactions among melts, aqueous fluids
and rocks," she explains. "One key to
the nature of the fluids involved in these processes
is the composition and density of minute fluid
inclusions that are trapped within minerals.
"I talked with Weecha
and she told me about a new technique that the
French were beginning to use to study these fluid
inclusions: laser Raman spectroscopy," Pasteris
recalls. Laser Raman microprobes enable spatial
imaging and spectroscopic analysis of sample areas
as small as one micrometer in diameter.
"I looked into it further,
and for some crazy reason — I wonder now
how I could be so bold — I thought I would
like to purchase one of these instruments. In
this country, the technology really got going
in the semiconductor industry," Pasteris
explains. "But at that time, none was in
use in a university geology department."
Nevertheless, Pasteris convinced
the university, corporate donors and the National
Science Foundation to fund her purchase of the
first laser Raman microprobe for a geology department
in the United States.
The
Instrument Guides the Interest
After meticulously testing
and validating the data generated by the instrument,
Pasteris and two of her Washington University
colleagues, chemists Brigitte Wopenka and John
Freeman, put it to work to study natural fluid
inclusions and experimental analogs.
As they learned more about
the instrument’s capabilities, it began to
guide their interest in new directions. For example,
they used the technique to shed light on the dynamics
of the 1991 eruption of Mt. Pinatubo in the Philippines.
By the mid-1990s, scientists in other disciplines
— from mechanical engineers to oceanographers
— became interested in Pasteris’ work
with the Raman microprobe.
Among the diverse studies
her group has worked on are the identification
of microcrystalline substances in human breast
tissue adjacent to silicone implants, the effectiveness
of fluoride treatments to decrease bone failure
in osteoporotic patients, and the feasibility
of stably incorporating greenhouse gases into
solid materials — essentially, carbonated
ices — for permanent storage on the sea floor.
Pasteris is sharing these
new insights with her graduate and undergraduate
students. In addition to teaching Earth materials,
mineralogy, economic geology and Earth resources,
she developed a new course in environmental mineralogy.
It covers such topics such asbestos/fibrous minerals
and their health effects, the mineralogy of arsenic
poisoning and remediation, clathrate hydrates
as sources and sinks for greenhouse gases, and
materials for nuclear waste storage.
The
Human Element
Pasteris contemplates the
implications for human health of her group’s
recent research in biomineralization and medical
mineralogy. "The positive side is that we
might provide additional information leading to
better knowledge of how to fight a disease,"
she muses. "I never saw myself in a role
like that before. That’s the gratifying part.
"The scary part —
and I say that only half jokingly — is that
if we made a mistake in a calculation or analysis
on a rock sample, it wouldn’t matter to most
people. Nobody’s life is hanging in the balance.
We are always meticulous about our analyses, but
we never before had to think about somebody’s
medical treatment being based on our knowledge.
That is in the back of our minds now."
Pasteris’ tone lightens
perceptibly when she considers the fact that her
research on storing greenhouse gases relates to
carbonate rocks. One could say that she has come
a long way since her Bryn Mawr days, when she
collected her first marble samples. On the other
hand, she says, laughing, "I’m back
to carbonates, so maybe I should think about having
come full circle!"
About the Author:
Dorothy Wright contributes
news and feature articles on science, technology,
engineering and general interest topics to a variety
of publications, including Civil Engineering,
Engineering News Record and Bryn Mawr
Now.
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