Above:
The Passaic Pit during the 2008 Diggg at Sterling Hill. At
left is a big boulder made of "salmon calcite". This is always popular
with collectors. The calcite is pink in daylight but also fluoresces
red-orange in short-wave UV. With some luck it's possible to find
spots of white-fluorescing barite in this material.
|
The 2008 Diggg was a success, thanks
to Jeff Winkler, Eric Weis, DVESS, the SHMM, and everybody else who worked
to make it so great. (If I missed your name for the credits, make sure
to email me so I can add it!)
It was really good to see everybody at the dig-- quite a few of the usual crowd, plus many new faces. This is what it's all about! Mineral collecting is one of the finest hobbies out there, but it wouldn't be the same without the great people. I wish I'd thought to take pictures at the banquet, an annual event that has its own cast of characters (many of whom are long-time field collectors who've graduated to the silver pick). I stayed at the banquet for about an hour and then hit the rock piles again. |
|
Within the Sterling Hill complex are some interesting sub-regions of mineralization. This time I focused mostly on some altered scapolite (photograph, below) from the Noble Pit. This material sometimes has cavities that contain micro crystals: there can be aragonite, calcite, cerussite, fluorapatite, goethite, malachite, azurite, or any of several other minerals. 
I have yet to go through all my collected material with a microscope. A potato-sized chunk can keep a person busy for hours. Trying to identify every mineral species in the rock can take much longer! The Night Dig - There were some fine specimens found. Eric Weis of glowhound.com came up with an unusually good SW FL fluorapatite. I saw a few people with nice, rich hydrozincites. I collected with Steve (a long-time Franklin collector) and his brother George; we got some lilac-fluorescing scapolite. It isn't very bright as fluorescent minerals go, but the color is intriguing. The specimen shown below is about 3 inches across. First, here's a picture of it in normal light: 
Now, here's the specimen in short-wave UV: 
Scapolite (Meionite) from Sterling Hill normally fluoresces a magenta color in short wave. The galena-bearing variety from the pits has a different response. It gives a subdued mix of pastel hues: lilac, orchid, blue, gray, sometimes even a bit of tan. It is vaguely reminiscent of some of the subtly-fluorescing "Parker shaft" prehnite specimens I've seen. This material may be similar to the Parker suite of minerals in more ways than one. It seems likely that Pb++ is an activator here, just as it is in most of those Parker Shaft minerals that fluoresce lilac, blue, violet, or peach; the peculiar FL response tends to occur in scapolite whenever there is galena in the rock. Of course, to get the ember-red fluorescence exhibited by the calcite, there has to be manganese as well. At both Franklin and Sterling Hill, it's almost a given that a rock will contain at least traces of manganese. I looked again to make sure I've captured the color response correctly. It is close but not perfect. The real-life FL response of this scapolite, although somewhat dim, is so nuanced and subtle that it is hard to describe, let alone capture accurately with a camera. You could be standing there with three different collectors and you'll get three different descriptions of the color. In fact, I think the three of us had been talking about this just about when the tranformer blew a fuse and the lights went out... all except the battery-powered UV lights the collectors were carting back in the pits. |
Shown above: another view of
that scapolite specimen. Notice the zones of different color within
the same mineral, presumably due to different activators. The non-fl.
areas are "dendrites" of manganese oxides / hydroxides (e.g., pyrolusite).
Once again, I don't think the camera adequately captures the color
response, but it's close enough to give you an idea.Below: A couple more photos (sorry for those of you still on dial-up connections). Shown below is another view of the Passaic Pit. In the foreground is the region where genthelvite was found a few years ago. I don't know if anyone found any this trip, but it's pretty rare at this locality. In case you're wondering, "where is everyone?", this is what happened. Shortly before I showed up to take photos, most of the people had checked out with their poundages and gone up top for the special mine tour (which I missed, unfortunately). They returned later for the night dig. I wish I'd gotten photos of the night dig, but I didn't feel like dealing with a tripod or camera in the dark. There is one collector crouched down back there. See if you can spot him. 
Above: In the distance, a collector stands at the entrance to the Noble Pit. Immediately to the left of that collector (your left, not the collector's), some azurite was found. I ran out of sunlight before getting the chance to wander over there. |
