Operations at Mount Mica & Orchard Pit Mines, Oxford County, Maine.
Coromoto Minerals Mining
Operations at Mount Mica, May and June, 2005
Diagram of the under ground workings at Mt. Mica June, 2005
|As mentioned in the last update, Jim
Clanin felt the competency of the
rock in the ceiling of our drift would allow us to widen the drift
substantially. The first 10m or so was only cut 4m wide. Now we decided
to go back nearly to the beginning of the drift and take a cut angled
into the down dip wall. This would make the drift wider the farther in
it went. We started the process by drilling
three 8' long holes with our drifter but taking care to assure that the
lower hole was well above the mineralized zone. If the shot went well
our drift would be more than a meter wider at the end of the
holes. After the shot we were pleasantly surprised to see that we
had just peeled off the roof of a pocket. Reaching in we could
feel large amounts of golden cookeite sand. Mary started to work the
pocket and soon she was finding nice smoky quartz crystals and gemmy
We continued this widening process until
we had reached the end of our drift. By that time we had widened the drift by
several meters. As we did so, we found a number of small pockets in the
down dip ( southern wall of our drift). Each of these carried a little
elbaite, some smoky quartz crystals and cookeite. In fact there was a
continuous seam of cookeite with minor lepidolite now showing in the
down dip face just above the garnet line . This was something new.
Heretofore, the cookeite was isolated to the cavities themselves. In
pocket number 7, opened May 17 during this widening process, we were
surprised to find two small clusters of rose quartz crystals. These
were embedded in a mass of clays that appeared to be an alteration of
some phosphate minerals... perhaps lithiophilite/triphylite. These
clays were in the apex of the pocket instead of the bottom.
Although Newry is credited as the type locality for rose quartz
crystals they may have been first reported from Mt. Mica by
Nevel ( Minerology of Maine Vol I). Frank Perham also found some
of these crystals when he
mined at Mt. Mica during the 1960s'.
Perhaps the most
notable feature as we continued to advance our drift
was the expansion of the Li bearing zone. Besides the lepidolite,
spodumene and montebrasite we becoming abundant and increasing in size.
plan was to continue to turn our drift to the south (down dip) we kept
it wide enough to maintain this Li zone exposed. We were now kept busy
collecting this material as much of the lepidolite was of carving
grade. Additionally our practice had been to remove the pegmatite
right to the hanging wall as this provided the most stable roof. The
trick was to not blast and fracture the schist that formed the roof.
Drilling horizontal holes to within .3m of the roof seem to provide
breakage right to the schist. Of course this required us to probe and
locate the schist so as to correctly locate the holes to be loaded. We
were surprised therefore when suddenly the schist rose by several
meters. It appears we had mined into another offset or thickening in
the pegmatite very much like we had encountered outside in the main
pit. ( See http://coromotominerals.com/MM04October.html ).
Perhaps the expansion of the Li zone was following similar pattern to
what we had observed taking place in the main pit. As discussed in
these pages the garnet line is the pocket zone signpost at Mt. Mica. As
the pegmatite thickened there was still a clear lower garnet line, the
one we were following, but now there was a confusing array of garnets
both in clusters and 'lines' ascending into the left hand or up dip
side of the drift.
As we advanced our
drift the pegmatite had been plunging to the east and
dipping to the south. This dip and plunge had required us to
repeatedly drop the floor of our adit so we could successfully muck as
we mined along. Before we knew it, the roof on the left side of the
drift was more than 5m above our heads.
Although the mineralization looked enticing and in fact there was
watering seeping from a rusty area, always a reliable pocket sign, we
had to temporarily abandon working the drift on the far left side and
now take a narrower cut as we advanced. In the diagram at the top
of the page the narrow cut is the start of another advance. We next
widen the cut down to the down dip face.
Besides the encouragement provided by the mineralization, the
appearance of a large rusty crack on the left side of our drift
portended a pocket ahead. Our group was somewhat divided on this issue.
Richard and I and seen this pattern a number of times so there
was little doubt on our part.
Jim and Richard beside the emerging mineralization May 27
Close-up showing tourmaline and pollucite
During June we continued advancing our drift and turning it down dip. I
was scheduled to give a presentation on Mt Mica at the Maine Pegmatite
Workshop. I planned to present my views on pocket signs
that work at Mt. Mica. So in order to validate my 'signs' I decided to
scan our drift looking for pockets using these 'signs'. After washing
the entire drift down we probed any promising looking spots. In
fact we found two small pockets. One was near the beginning of our
drift and one was in the floor of a burn just completed by Richard and
Jim. The pocket in the burn cut, which Jim opened with his scaling bar,
produced some fine blue gem elbaite.
We were becoming amazed at the quantity of lithium minerals that were
now showing up in our drift. Our next advance produced both a widening
and thickening of this zone. In Maine, Black Mountain is noted for its
huge mass of lepidolite with locked in rubellite crystals. Though I
have not been to Black Mountain I am told by others that the pod we
were now exposing was even bigger. Everything associated with this
mineralization was on a scale larger than we had seen at Mt. Mica. For
example there were several exposed microclines more than a meter in
length. The mica books, many of which were rimmed in lepidolite, were
up to .5m in length, We were not expecting to find pockets with such
lepidolite but we knew from experience that what once we reached the
margins of the mass we could expect to start finding pockets again.
Would these be on the scale of the mineralization too?
Jim and Richard beside
the enlarging mineralization June 17, 2005