|Mining Operations at Mount Mica & Orchard Pit Mines, Oxford County, Maine.|
Coromoto Minerals Mining
Operations at Mount Mica,
September and October 2006
The best material from day 1 of pocket MMP21-06
As described in the last update, June/July/August, we were all intrigued by the increase in the grain size of the pegmatite. The huge and never ending feldspar crystal seemed to promise something worthy of note. Therefore, we decided to put in yet one more advance, the third, over this area. As with the other two, we turned this advance to the south. We were essentially driving a curved drift as we wanted to explore the plunge more fully. We had been keeping the advances relatively narrow, about 5 meters wide, as we felt that we had made the gallery of our stope as about as wide as we dared. The plan was now to drive a more narrow cut and, once we had advanced sufficiently, we would turn to the north and start another gallery. This would leave a wall between the current gallery and the one we planned. If necessary, we could mine though a portion of the wall into the original gallery while still leaving 3 meter square pillars to support the roof. The diagram to the right shows the upper end of the stope. The solid area is unmined. The dashed area and arrows indicate the projected scope and direction of the next phase of our mining.
As we drilled the burn we were impressed by the amount of rust colored cuttings we were getting. This was indicative of cracks...and cracks were a good pocket sign. Richard, controlling the pressure of the leg while he drilled, felt the area was soft, yet another good indication. Once drilled and loaded, the burn pulled reasonably well. After hoeing out muck, we could see several very rusty cracks. These were filled with loose muddy material. In my view large pockets at Mount Mica are rusty because of these cracks. Either the pocket formation process or the presence of the pocket itself weaken the pegmatite such that cracks develop to the upper contact. Surface water tends to migrate along the contact until a crack is intercepted. Then it proceeds downward bringing with it iron oxides and fine clay particles. However, there was another promising feature to these latest cracks. Several had become lined with quartz and, in a yet more encouraging sign, locked within this quartz were small colored tourmalines. The lining reached very close to the upper contact well above the normal level of the mineralized zone. This portended a large pocket in the vicinity. Yet one more feature surprised us. Within one of these in-filled cracks, high above the mineralization, was a vug that actually contained small gemmy tourmaline crystals. We had not seen this since pocket 7-04. Emboldened by these features, we tried to preempt the 'discovery' process by projecting the trend of these cracks down into the mineralized zone. We then used our sinker drill to attempt to drill into the pocket (s) that we were certain were there. No luck.
After our pre-emptive strike failed, we reverted to 'doing the necessary' and drilling a horizontal pattern into the mineralized zone. We planned to drill two rows of 4 holes 3m long. Certainly we would drill into something in such a promising looking area. My disappointment was building as we drilled hole after hole without going into a space. Finally, while drilling the 8th and last hole on the far left bottom and just before the hole was finished, the drill bogged down then moved ahead without rotating. We were in a space and it was draining water! We hoped this was a significant space. The chants of 'Fucom!' began This is a term for pocket we learned from the Brazilian gaimperos Richard and I met in Parelhas, Brazil. It translates locally as 'oven' and is perhaps a better term than 'pocket'. Regardless of language or terminology, the rush miners experience when finally finding a pocket must be universal.
We, or more accurately said, I, made a mistake when in blasting to expose this pocket. As always our goal is to remove rock such that the final entry into a pocket can be done with hand tools or a chipping hammer. In this case, I choose to load holes 2, 3 and 7. 7 was the hole just to the right of 8, the one that intercepted the pocket. When I made this decision I did not know that the pocket was precariously close to 7. Had we not drilled into the pocket on our very last hole, we would have had the energy and enthusiasm to drill a 9th hole to the right of 8. We would have then drilled into the pocket again. With this knowledge, we would have loaded 2,3,4 and 6. This would have required more chisel work, but the subsequent minor damage would have been avoided. At the left is the 'fruit of our labor' just as it appeared after the blast. The pocket opening is visible near the bottom center of the picture. Frank Perham loans his hand for scale. He is pointing at a development in the feldspar just above the pocket opening. Dubbed by us 'zebra spar', it appears to be an extremely coarse perthite. It was late in the afternoon on the 13th of September when we opened the pocket. Since we work strictly by the clock, we did not have a lot of time before the 5 o'clock whistle blew.
The next day, as we resumed excavating the pocket , it was hard to believe that our blast had loaded the pocket so throughly with feldspar 'chowder'. In fact, we started to believe that the pocket consisted of only of these feldspar chips. WE, however, were quite wrong. As we finally got to the end of the blast debris, we began to get a glimmer of the true nature of this space. To the left we could see fragments of a large tourmaline, directly to the back, the top of a large tabular beryl protruded from the pocket material, and, finally, to the right was a large parallel growth smoky quartz crystal. Per established procedure, we began loading the loose material into 5 gallon buckets. Betting the pocket was not just feldspar chips, the night before I contacted Missy Robinson and alerted her that her services would be needed at the screening table. At that point I was not aware that the table would be in operation for more than 6 weeks. Though we were sending the loose material out in the buckets, we were taking time to admire the better material. The pocket was only slightly rusty at this point so the viewing conditions were good. In the image to the left below I'm holding the tourmaline section up to a drop light. To the right, I've placed my cap light behind the beryl to see how translucent it was. This pieces were nice, but the true surprise would come shortly.
After removing these pieces, I decided to take them outside for safe keeping. There Richard and Missy were intently examining something at the screening table. Richard stuck out his hand. It was filled with rose quartz crystals! This was really an exciting development! The occurrence of rose quartz crystals at Mount Mica, however, is not new. Van King's historical research shows that George Howe, the famous Oxford County naturalist, found some on the dump in the 1920's. His find, though not official, pre-dated the 'initial' find at Newry, Maine, the type locality for rose quartz crystals. Frank Perham found some when he mined the eastern end of the Mount Mica pegmatite in the 1960's. We too had found a pocket last year with two small groups of rose quartz crystals. One group was clearly pink, the other required a bit of imagination. Those laying on Richard's palm, even though significantly rusty, required no leap of imagination to conclude they were pink crystals. They were elongate and gemmy. I had noticed a skirt of these odd shaped crystals on the bottom of the parallel growth smoky we had retrieved from the pocket. I hastily unwrapped this big quartz and held it up to the sunlight. To our amazement and delight, these too were pink and they formed a skirt that went all the way around the crystal. These were reminiscent of the famous Brazilian find at the Lavro Berilo Branco mine in the 1959. Frankly, we were stunned by what we had found. ( To the left is an image of the crystal after cleaning off the rust. It is 23cm tall)
We dig all pockets with enthusiasm, but now we were really charged up. This was indeed a good 'Fucom' even by Brazilian standards. Now we were taking more care when working the pocket as the pink quartz crystals were quite thin and therefore fragile. By and large they seemed to be occurring as very late stage growth on the smoky quartz.
To be continued