By Keith Barron, Consulting Geologist
An exciting new exploration play is unfolding in Canada, far
from the frozen tundra of Lac de Gras, in rolling farmland just a
day's drive from Toronto. Diapros, a De Beers subsidiary, had been
working quietly in this area in the early 1960s. It was joined by
four other companies, who worked through the late 1980s until they
abandoned the area for prospects elsewhere. But others have
filled the gap, using new techniques and ideas which are yielding
sparkling success. I entered the scene in 1991, following up on a
reference in a 1906 U.S. Geological Survey Report to a large diamond
found in the Nipissing district of Ontario. My research uncovered a a
jewelry trade article of that year describing the stone as "large as a
hen's egg with a rough surface and a yellowish tinge." The
stone had passed through the hands of a priest, a colonization agent
for the Canadian Pacific Railway, and Adolphe Aubin, Member of
Parliament. Ultimately, it was sent to Tiffany for cutting. The story
rang true, especially since the location of the find -- on the west
side of Lake Timiskaming -- matched the location of two kimberlite
pipes found 75 years later. An actual-size drawing of the
stone in the Mining Journal of London showed it to be 54 x 40
millimeters. The weight was not recorded, but some quick math renders
an approximate weight of more than 700 carats. How the
discovery escaped world attention was a quirk of history. The find was
made near the settlement of Cabalt, where three years earlier, silver
veins were uncovered by railway workers. This led to a silver rush,
with all it's associated wild rumors and con games. The Provincial
Geologist, Willett Miller, was badgered by prospectors for glowing
endorsements of their claims, prompting him to refuse to visit or
write about the area for a full five years. He probably considered
reports of a giant diamond to be a hoax. The Montreal Herald
reported that Tiffany sent geologists to investigate the area, but
it's quite possible they decided against sharing their information
with the press, particularly with a silver mining tent city down the
road. There is, however, strong evidence that the stone was
real. The granddaughter of the original owner, Nicole Aubin, claims
that her sister owns one of five stones "cut from a large rough
diamond owned by her grandfather,"
On the Trail
The two pipes known when I started exploring the area in 1992
both contained diamonds, though at uneconomic grades. Geologist Bob
Barnett and I believed the source for the legendary Nipissing stone
lay undiscovered nearby, so we used a method of exploration that has
been successful elsewhere in Ontario -- looking for kimberlite
fragments in the glacial gravels of the area's commercial gravel pits.
The glaciers of the last ice age caught fragments of rock in
their undersides as they ground their way southwards. Rock would drop
out on the way, leaving a trail. By following the trail backward, one
finds the source of the rock. This exercise has been repeated many
times by other companies and the trail always appeared to lead back to
the two known kimberlites. They had assumed that those were the
sources of the fragments. Their assumptions, however, proved wrong,
because drill core samples from the two pipes showed no correspondence
with the gravel pit fragments. We staked a large number of claims in
the backtracked glacial direction from the pits. We were hot on the
trail but still the source eluded us.
The OPAP Pipe
The following spring, we convinced a Vancouver junior mining
company to take on the project. The next step would be an expensive
airborne magnetic survey, which can pinpoint from the air buried
magnetic rocks such as kimberlite. The survey revealed several likely
targets which appeared as a round bullseye on contoured maps. A large
negatively charged bullseye could be seen south of the two known
pipes, between them and the gravel pits. However, common wisdom
dictates that kimberlite is found in positive bullseyes. Thus, the
company drill tested those, coming up empty-handed. We were
convinced, through our own experience and that of Ashton Mining in
another negative bullseye exploration, that our negative target was a
pipe. The financing to test the theory, however, was hard to come by.
Fortunately, our third partner, John Ewanchuk, owned his own drill.
With a $10,000 grant from the Ontario Prospectors' Assistance Program
(OPAP), we did a ground magnetic survey to lay out grid lines. We set
up the drill on September 10, 1994, and hit a pipe at 70 feet.
New Discoveries
Earlier this year, the Opap and adjoining area were optioned
to Vancouver junior company Consolidated Pine Channel Gold Corp. Just
several weeks ago, Pine Channel announced the discovery of two new
pipes, and others are expected. The new pipes are only 5 to 12 feet
deep and can be easily uncovered with a backhoe. Company
President Dale Hoffman says that the area's paved highway network,
infrastructure, local mining expertise and the shallow nature of the
pipes will keep mining costs low, a fraction of the costs for the Lac
de Gras mines. This means that much lower kimberlite grades will be
mineable at a profit. However, Hoffman isn't expecting low
grades. He's hoping that other stones like the Nipissing will be found
in his test samples. Two tons of core have been drilled from Opap,
which are now being analyzed. Other large samples from the two new
pipes will follow shortly. This will be an interesting one to watch!
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