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Harding Pegmatite Mine
Stunning University Treasure
Terry Gugliotta , UNM Archivist
tgug@unm.edu
About 5 miles north of Dixon, New Mexico lies an unusual treasure of the University. Just off of
Highway 75 on an unmarked dirt road appears the tell-tale turquoise sign--”The Harding Pegmatite Mine -
University of New Mexico."
The mine, which was generously donated to the Earth and Planetary Sciences department in 1978 by Dr. Art
Montgomery, played an important role in WWII and in the lives of the people of Dixon. The mine also
contributed to the establishment of geologic theory and is used today as an outdoor laboratory for
geology students throughout the country.
A pegmatite is a small body of igneous rock that is formed from the crystallization of molten rock. In
some cases, like that of the Harding, pegmatites are rich in rare elements such as lithium, tantalum and
beryllium. The Harding is special because it is so well exposed and, after years of mining, much of the
mine still remains.
“It’s very unusual to have a mine like this open and available to the public,” says Regent Professor Rod
Ewing who oversees the mine.
UNM students visit the mine during their sophomore year and for many it is their first experience in the
field. Before heading to the mine, students use the vast Harding archive, which includes mineral specimens,
drill cores, mining claims, photos, maps and nearly 100 scholarly papers on all aspects of the mine, to
study the geology and mineralogy of the area. As part of their field trip, students map the pegmatite,
which Ewing saves and includes in the archive.
Also leading the mineralogy students to the mine is Geology Professor Cornelus (Case) Klein, who calls it
“a stunning textbook illustration of minerals in the real world” that gives students the chance to see
the minerals in nature.
One former UNM undergraduate student, Bryan Chakoumakos, who wrote an honor’s thesis in 1978 on the
crystal chemistry of the microlite, became so taken with the mine that he put together a walking tour
that is used by students and other visitors today. Chakoumakos went on to earn a PhD in geology in 1984
from Virginia Tech. He now works at Oak Ridge National Laboratory.
"It's a unique locale. I’ve seen pegmatites all over North America and
Australia and the Harding is by far the best exposed and probably the best
place to learn. It's a textbook example," says Chakoumakos
In the 1950s, pegmatologist Dr. Richard Jahns used the Harding Pegmatite for his studies on the
composition of pegmatite melts. The results of Jahns' field studies and
experiments are the basis for present-day understanding of how pegmatites
form.
Any student who studies pegmatites will inevitably be exposed to
Jahns' writings on the Harding Pegmatite," Ewing notes.
The Harding is so unique and well-known that geology professors from around the country bring students
there to study. Princeton geologist Dr. Linc Hollister visits the mine with his students each summer.
"As a teacher, I am able to help students make the leap from the abstract and theoretical to real
world, three-dimensional minerals in their entire geologic setting. I know of no other place in the
country where students have access to such a unique educational tool," says Hollister. "It makes such
a difference."
The mine attracts many visitors. While some are geology students, most are simply rock hounds.
Visitors are allowed to take small rock and mineral specimens home. The Earth and Planetary Sciences
department employs the Griego Family of Dixon to look after the mine and its visitors. Gilbert Griego,
who played at the mine as a child, often accompanies visitors to the mine and identifies the minerals.
Gilbert'’s father, Elise, and his uncle, Flaudio, worked at the mine during WWII.
"We get people from all over the U.S. who visit the mine--especially from the East. We also get
people from Spain, France, Japan and England. "It's fantastic", says
Gilbert Griego.
Although mining at the Harding took place from 1919-30, it wasn’t until 1942 that the mine attracted the
attention of the U.S. Government. At that time, the U.S. War Production Board was so desperate for
tantalum it was having the ore flown in by bomber from Australia. The U.S. needed tantalum to
manufacture walkie-talkies and radios for the armed services.
In 1942, Montgomery, then a young Princeton graduate working for the Titanium alloy manufacturing
company Tamco, called a friend, geologist Esper Larsen, at Harvard. Larsen told Montgomery that 20
years earlier he had collected mineral specimens of lepidolite, a lithium-bearing mineral, from the
Harding Pegmatite mine near Dixon. Larsen said he thought microlite, a tantalum mineral, was
also present.
Montgomery headed for the mine. He searched the quarry dump looking for microlite, which, in its purest
form, is nearly colorless. As he picked up pieces of lepidolite, Montgomery could tell something else
was present. The lepidolite was too heavy. He began wetting the specimens. “Microlite has a high index
of refraction. He began wetting the specimens and the microlite, which has a high index of
refraction, became visible.
"I was spitting on it and the tiny crystals of microlite began sticking out like a sore thumb,"
Montgomery recalled.
Montgomery wrote an enthusiastic report to Tamco stating that the Harding Pegmatite contained one of the
important ores of tantalum. The next step was to make legal arrangements
so that the company could start test drilling, Montgomery said.
The mineral leases were split among the heirs of the three original owners. Montgomery obtained the
services of a mining lawyer in Santa Fe who found the heirs, a process that took several months. In the
meantime, Tamco lost interest in the mine.
"The company decided after a while that I was overly enthusiastic about the possibility there--you
couldn’t see much tantalum around" Montgomery said.
His enthusiasm remained and with the Tamco's blessing, Montgomery resigned in order to pursue the
possibility of mining the tantalum himself.
After the heirs were located, a public auction was held for the mineral leases. Montgomery was the only
bidder. With no capital, Montgomery worked out six-month payments to the heirs.
"I didn't know at the time, but after about six years I ended up being
the owner of the mine. Never expected such a thing," Montgomery said.
After he purchased the mineral leases, he contacted members of the War Production Board about
mining tantalum. Desperate, they agreed to give his operation the highest
civilian priority and buy his tantalum ore by the ounce.
Thus Montgomery, an Easterner with no experience mining or running a business, found himself
embarking on a strange endeavor in the Southwest. He hired six men from Dixon to help him mine. Most
of the six had worked at the mine in the 1920’s during the lepidolite mining
The microlite ore was so precious that Montgomery didn't dare do any blasting. The miners chiseled
the ore out of the open pit and Montgomery chipped off excess minerals -- all by hand.
"That was the kind of operation we had. Nothing could have been more
unorthodox, but we were all good friends together," Montgomery said.
The ore was shipped by railway express to a Bureau of Mines experimental milling plant in Missouri and
milled for free. It marked the first time in history the Bureau of Mines ever handled a commercial ore,
Montgomery recalled.
During the 1960s, Montgomery leased the mine twice to different corporations. No significant mining
took place, but Montgomery still received royalties, which he used to fund scholarships for worthy,
education-minded students from Dixon. From 1965 to 1982, when the fund was depleted, more than 20
students attended UNM with these scholarships.
In 1978, Montgomery, wanting to preserve the mine as an outdoor laboratory for mineralogy and
geology students, decided to donate it to UNM. The transaction did not go smoothly, however, largely
because the mining claims were on both State and Federal land. Lawyers representing the University,
the Bureau of Land Management and the State competed over the best way to deal with the property.
After one of the meetings, Ewing suggested, jokingly, that the land be transferred by Act of
Congress.
"I had no idea that was possible" Ewing said, "but it was."
A University lawyer contacted U.S. Sen. Pete Domenici (N.M.), who agreed to sponsor the Act. It
became law Oct. 30, 1978 and the 110-acre tract of land became the property of UNM.
The act contains an unusual provision, stating that if the Secretary of the Interior determines
that the unmined mineral resources of the Harding Pegmatite are needed for the security of the United
States, UNM must lease the property to a Secretary of the Interior designee for mining and pay any
royalties to the U.S. government.
In the meantime, the mine is available for researchers as well as rock hounds.
"The most important thing is different universities come to the mine
and this is really what it's all about. It serves as an outdoor lab for
geology students. So the effort that UNM and Dr. Montgomery put into it is
really paying off," Gilbert says.
from Quantum, v. 13, No. 2
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