Colorado State University Uses Revolutionary Methods To Date Minerals In New Laboratory
Wednesday, April 23, 1997
FORT COLLINS--A new laboratory at Colorado State University
is using cutting-edge techniques to determine the age of sulfide
minerals, allowing mining companies to better pinpoint ore
deposits. The technique also can be used to help environmental
agencies trace contaminants from mining and other operations back
to the source.
The Applied Isotope Research for Industry and the
Environment laboratory employs a new method to measure the
radioactive decay of the parent isotope rhenium against its
daughter isotope, osmium. Until recently, chemical processes did
not exist that could extract rhenium and osmium--which occur in
minute amounts--efficiently enough to measure the isotopes and
date the minerals.
The AIRIE lab includes a 4,000-pound mass spectrometer used
in the dating process, located in the university's department of
Earth resources in the College of Natural Resources. Colorado
State spent $110,000 to renovate two large rooms to house a new
chemical laboratory and the mass spectrometer.
Renovations were recently completed and the first mineral
samples are in the initial stages of being processed, said Judith
Hannah, head of the department of Earth resources and an
associate professor.
Hannah said the lab will be completely self-sufficient,
generating funds from research agencies, clients in the mining
industry and from geological survey agencies worldwide that want
to more accurately define the location of sulfide minerals or
trace contaminants. Hannah is coordinating the project with Holly
Stein, an affiliate faculty member at Colorado State and the
principal force behind the lab.
"There are only a few labs in the world that can analyze
sulfide minerals with enough precision to provide useful ages and
tackle the full range of ore deposit types," Stein said. "With
ore deposits growing increasingly hard to find, this lab will
provide a clearer picture of where to look. It will also give us
another tool in tracing environmental contamination back to its
source."
Radiometric dating determines the age of rocks or minerals
by measuring concentrations of naturally-occurring radioactive
isotopes, which decay at constant rates and produce daughter
isotopes. The amount of parent and daughter isotopes enables
researchers to determine the age of a rock in millions or
billions of years.
Hannah explained that for years, researchers knew rhenium
and osmium existed in sulfide minerals, but could only measure
them in minerals with unusually high concentrations. Even
minerals with large amounts of rhenium presented analytical
problems that prevented accurate dating.
One example of a rhenium-rich sulfide mineral the AIRIE lab
is now able to analyze is molybdenite, an important ore mineral
produced in Colorado. Molybdenite is the ore for the metal
molybdenum, a major component of high-strength steel. Stein
points out that working with molybdenite provides a means of
dating both some of the youngest and oldest rocks on Earth.
Recently, new chemical methods were developed to extract
rhenium and osmium from a wide variety of rocks and minerals,
Stein said. Equally important, improved analytical techniques
allow more precise measurement of isotope ratios in minerals with
very low concentrations of these elements.
John Morgan, the chemist who pioneered the chemical
processes now used to extract rhenium and osmium, will join the
AIRIE group this summer. Another addition is Richard Markey, a
research technician who has helped to oversee the laboratory's
construction since last fall.
While the laboratory offers cutting-edge methods in
radiometric dating of sulfide minerals, the equipment and
technology also have other important applications for research
under way at Colorado State.
Jerry Magloughlin, isotope chemist and assistant professor
of Earth resources, uses similar techniques to date the movement
on ancient faults to better understand Earth history and the
behavior of modern faults.
William Sanford, assistant professor of Earth resources who
specializes in hydrology, uses radioactive isotopes and their
daughter elements to trace the movement of contaminants in water.
Sanford's research could lead to new ways of identifying sources
of contamination and tracking water pollution.
"This is the kind of collaborative research that benefits
Colorado State's efforts in studying all aspects of the Earth in
a way that benefits both industry and the environment," Hannah
said.
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