Mining at the Mt. Mica, Orchard and GE Quarries
Oxford County, Maine

Coromoto Minerals
The 2003 Season  at the Mt. Mica
----  September and October -----
Page 1

Pocket 9 Citrine Quartz Crystals
Pocket 9 with some of the kaolin washed away.

By  the first of November our mining efforts had brought us eastward to the western edge of the Plumbago workings. These workings were the extension of the Merrill and Stone workings of 1890 to 1903 and, which in themselves, were an extension of the Hamlin workings ( father and son). Elijah, the father, along with his friend Holmes had found the first tourmaline here in 1820. As we neared closer and closer to the edge of their working and as we had found no colored tourmaline, I wondered often, as I gazed up at Merrill's high muck pile, what prescience they possessed not to veer westward along the course we had just mined. When Richard and I had at first exposed the westward extension of the pegmatite with nothing more than a water hose, we imagined that we had found some untapped reservoir of  tourmaline at Mt. Mica. Given the fact that the pegmatite dips under the overburden  to south and this dip had deterred each successive wave of exploiters starting with Elijah, we congratulated ourselves on our casual discovery. Although we were to be disappointed in finding no tourmaline pockets, we were more than adequately rewarded in our efforts otherwise. 

By the time we had reached the old workings we had mined a rectangular area 90 feet to the east and 50 feet to the south. The pegmatite on the western edge was typically only 4 to 6 feet thick but gradually thickened to more than 10 feet  as we mined eastward. About mid-way eastward and 40' down dip the pegmatite suddenly dropped about 6-8' in a near vertical fashion. This is very similar to the Hamlin description (History of Mt. Mica-1895 page 48) of  ' almost perpendicular inclination' of the 'granite' at the back of the Merrill pit. This is the point in 1891 where Merrill decided to try his luck eastward along the pegmatitePegmatite plunges in Plumbago pit. The unfortunate result of this 'inclination' is the overburden, which steadily increases down dip, now undergoes a significant increase as the pegmatite descends.  As Hamlin's 'inclination' was successfully mined through by Plumbago and another is clearly visible on the eastward end of the Plumbago workings (photo at right), these plunges do not appear to be catastrophic. The plunge we have encountered is the westward extension of the Plumbago shift visible in this photograph. As of this date we have not mined significantly southward of our shift, but it would appear the pegmatite is somewhat thinner beyond the plunge. Up dip of the plunge the schist overburden had steadily increased from near nothing to about 6'. The plunge has increased this schist layer to in excess of 10'. There is another feature that we encountered that appears to play a part in or be a product of pocket formation. This feature is the appearance of rolls and humps within the pegmatite. Interestingly, one can predict the presence of these features while removing the schist and before the pegmatite is reached. The schist bedding, when viewed in cross section, will have an obvious thrust upward and frequently is so severely fractured it can be dug off with an excavator without blasting. Pocket # 8 shows swelling in the pegmatiteThe picture at the left shows the thickening in the pegmatite. A remnant of the schist can still be seen folded across the top. Pocket number 8, a large 4x5x2' pocket, lies just 6 inches behind the rusty area in the middle of the image. 

During July and August we had encountered 6 pockets. The earliest ones were marked by especially nice quartz crystals with smoky overgrowths and some small apatites with cabonate-fluorapatite coatings. Pockets 5 and 6 had produced some stunning apatites. As we mined ahead eastward and removed schist we encountered 2 very significant humps in the pegmatite, similar to the one that produced pockets 1-4, but even larger. We speculated that surely in the middle of the largest hump there was a mammoth pocket waiting to be dug out. So with great expectations, which we tried unsuccessfully to keep in check, we started to bench through this boil in the pegmatite. Our hopes began to fade by degrees as each slice failed to reveal anything. As we were taking a cuts 50' wide by 6-8' tall by 4' thick , each pass took about a week of  drilling, blasting and mucking.Pocket8  Finally we were on the precipitous backside of the first roll and on its highest point.  Drilling holes 8' deep, well below the garnet line which at this point was about 2' below the upper contact, we drilled into a pocket at 6'. This was very curious as it was much deeper that any other we had encountered. Just eastward and up dip of this point, Plumbago had cut a road into their pit. The garnet line was clearly visible just 1' down into the pegamtite they had left. Just 4' down dip from their road we had drilled into a pocket some 5' lower.  (The garnet line is the demarcation at Mt Mica below which, over the years of mining, no pockets or minerals of great interest occur. )  The depth of this pocket required us to backup and drop the floor in front of the bench lower to insure that our blast would break below and in front of the pocket and not through it . This, we hoped, would prevent casting the contents of the pocket across our pit. Our first attempt at opening the pocket resulted in very little rock movement. We had decided to load and shoot holes that we felt were adjacent to but not in the pocket. The explosive force of the blast was easily digested by the rPocket # 8ock, suggestion that perhaps we has blasted into the pocket...not a good thing. We were able, however, by some determined chipping to open a small hole into the cavity.  This was pocket  #8 and it quickly expanded to into a large space.  Here Richard stands beside the partially opened pocket. The pocket's production included numerous nice smoky quartz crystals.  The best pieces,  however, were  3 quite large royal blue apatites. Each of the crystals has a unique form in its termination. Once we had finished digging # 8 out, a two day operation,  we spent time to carefully expose and clean the garnet line under and around the pocket. It was plain to see that the  wispy irregular garnet line in the Plumbago road had descended sharply by 4 feet blending into a large mass of cleavelandite chock full of garnets golf ball sized or bigger.  This mass looked like a bowl of cereal and milk filled with raspberries. It formed the base onto which pocket #8 sat. Continuing to trace this line up dip, we could see that after rising up towards the road it  descended sharply again. Prior to finding #8, we had attempted to mine this area but when our up dip shots didn't break the rock  we laid it off to a poor drill pattern or insufficiently loading the holes with explosives. Now, a different  thought  was beginning to geminate and set down roots . 

Pocket 8 apatites
The best apatites from pocket 8 fresh out of the ground and quite dirty.
Quartyz xtals in Pocket 8
Smoky quartz crystals in the right chamber of pocket 8 embedded in kaolin. Crystals are about 25 cm. 
One of the apatites from Pocket 8
One of the apatites from pocket #8 after a little cleaning. The crystal is 7 cm long.

We therefore decided  to back up and try another hole a little closer to the free face on the up dip side of our workings. After the blast we came down to check the results of out work. Again,  it appeared, the shot did not pull very well. We probed an abundance what looked to us at first to be blast chowder, rock that is pulverized in place and not moved and a sign of poor blast planning.  Probing with sticks, more and more of this chowder easily was dug out. As the quantity of this material mounted, I began defend my blast to Richard and Frank Perham. This material could not be ALL chowder. At first comprised of loose cleavelandite blades, the material gradually began to mix with muddy kaolin. Finally, fractured quartz crystal faces began to emerge. We had found pocket #9. Like 8, pocket 9 was quite large. One thing struck us almost immediately. It was filled with a great deal of very creamy white kaolin.  Much more than we had seen in the previous 8 pockets. Washing this kaolin away revealed citrine quartz crystals of excellent quality and very large mica books with an alteration on their sides. We were beginning to appreciate that the apatites formed in the ceilings of the pocket and were also embedded in kaolin. Pocket 9 had all of the right ingredients, but we found no apatites. 

Pocket 9Citrine quartz crystals in kaolin, pocket 9
Two views of pocket 9 with some of the kaolin washed away. 

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Pockets 10 and 11

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June 2000 Beryl Group