The 2004 Season at Mt. Mica
---- May -----
A screen load of tourmaline and other minerals from Pocket 7
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As we continued to work the pocket 7 (MMP7-04), we could detect a narrow space that seemed to be going down. Each of us took many turns at groping inside of this space. It seemed for a time that this might be the bottom of the pocket . There felt to be, as our senses where confined to our finger tips, a large lump in the back. We use a garden hose connected to either our 2" gasoline pump run on idle or to our electric pump as our primary digging and exploring tool. However, no matter how much we blindly washed into this cavity or scratched and pawed with our fingers, we could not seem to move this piece in the slightest. Perhaps it was just a feldspar plate attached to the pocket wall. It would be unlikely though that this would be the bottom as we were still several feet above the garnet zone. Generally pockets at Mt.Mica extend down to the 'garnet line' where they end in a layer of cleavelandite with a few cassiterites mixed in. In the image Mary again shows excellent 'form and technique' as she had her go at finding something. Richard is obviously amused. So once we reached a point of diminishing returns, I decided to test the depth of the pocket by drilling the 'floor' with our small pneumatic hammer. So as Frank Perham grimaced and worried that I might perforate some important speciemn , I gingerly drilled the floor. The drill worked its way into the bottom for a few inches and then dropped into an unseen cavity below.
Now that we knew we were just dubbing around on the top of the pocket our next move was to open it more. We drilled a series of holes around what we believed to be the periphery of the pocket trying to 'sound' its dimensions. Once we had an idea of the margins we could take the gamble and carefully use a small amount of explosives to open the pocket. This is a risky business and I take it upon myself alone to decide this move. Although there is no shortage of ideas, my feeling is that if a major specimen is going to be destroyed, better to do it myself. As I tell people, if I follow your advice and it goes wrong, I'll be mad at you for giving it to me, I'll be mad at myself for accepting it, and you'll feel bad for giving it. If I call the shot and it goes bad, I'll be mad at myself and you'll have the pleasure of the ' I told you so's'. In my business life I frequently tell people I don't mind making decisions and in fact I don't even mind making an occasional bad decision. Its just the ratios that count. So, what we have been doing all along to hedge our bets and shift the ratios, is to drill to the lower contact. By doing this, the charge, if sufficient care is taken, is actually beneath the garnet line and the pocket zone above is lifted by the blast. The odds of a direct hit into a pocket are somewhat diminished. That's the theory anyway. The down side of this extra drilling is the generation of more muck. So once we felt we knew the approximate location of the pocket, we loaded two holes on either side of its presumed loaction and somewhat in front of it. Then we prayed or I did anyway.
After the fumes cleared, we came down into the pit to assess the damage. We were lucky this time as we had just blown the front off of the pocket exposing a 3' thick layer of pocket material. ( see image above) After setting up our ' hydraulic excavator' ( garden hose), we began carefully to wash some of the pocket mud at the front. Within a few minutes we had identified our lump. It was a huge crudely formed tourmaline immediately dubbed the ' bowling ball'. The tourmaline had wedged itself in the top of the pocket creating what seemed to be the bottom as we had worked it from above. After struggling for awhile we were able to remove this specimen. Excepting it's size, it wasn't much to look at. Many sections of it's termination were spawled off. We collected as much of these as we could to try for later rehabilitation in the laboratory. We continued to work at the pocket by exploring the top layer of debris as far back as we could. By the end of the day we could insert the hoe handle all the way in and still not touch 'terra firma'. This was a big pocket that apparently had the ability to make big tourmalines.....the little gears inside our heads whirred at a feverish pace imagining what mineral cornucopia was contained under all that debris. So far in this chamber we had only found the Bowling Ball. Unfortunately, it was getting late and it was time to button this pocket up. Some time back our Mack dump truck had decided to sluff off it's tailgate bringing the hinge points with it. So with the heavy tailgate covering the pocket, huge boulders stacked in front and water rising into the pit, we felt comfortable in leaving for the night. In addition, a former Rumford police officer would be providing extra security.
The next day, Friday, May 14, we continued to work the pocket. This pocket was exceedingly rusty so the visual delights in discovery of its contents was somewhat hampered. For me, seeing an important specimen freshly exposed but still lying in place is a rare treat and is to be savored slowly. Working the pocket with a garden hose has greatly increased the number of these quality experiences. So far, as we worked the pegmatite this year, we had only green tourmaline. This day our hosing though would uncover a color zoned tourmaline for which Mt. Mica is famous. Like most Mt. Mica tourmalines, this one, although quite large, was broken into countless fragments. To borrow from A.C Hamlin's style, it appeared that nature, in a fit of rage, smashed the crystal. On a less melodramatic note there is a tendency for the the tourmaline at Mt. Mica to part along color transitions. For example tourmalines that are black at the base frequently part at the transition to green. Occasionally, after the separation, the crystal continues to grow or heal. Hence, this fragmentation may not occur during 'pocket ruptures' as it is doubtful the environment necessary to foster additional growth would be preserved after such an event.
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