New Uranium find at Bryson City, NC
Posted: Thu Dec 29, 2005 2:27 am
Recently I drove back through the western part of my home state to investigate some apocryphal claims of uraninite sediments in Deep Creek, which drains out of the southern part of the Smoky Mountains into the Tuckasegee River near Bryson City. The uranium deposits that are well-known in NC are mainly near Spruce Pine, which is a long way from this site and geologically quite different.
I didn't relish the idea of panning for minute uraninite crystals in the frigid mountain stream itself. Before going, I tried to pinpoint outcrops that might have been responsible for the placer uraninite, including a bunch of granite pegmatites near Deep Creek that had been mined previously for kaolin and feldspar. I didn't find any reports of uranium or thorium from these, however, so I thought the chance of finding any radioactivity would be remote.
I picked up Q in "downtown" Bryson City (he lives nearby) and we went to work with scintillators on the sites I'd mapped out. One site, including the dump of the old Deep Creek No. 1 Feldspar Mine (35°27'12"N , 83°27'20"W), was amazingly, wickedly, radioactive--much to my surprise. Big lumps of a black, dense, very radioactive mineral line this dump in profusion. Much of this material will peg out a CDV-700 and some pieces will peg it with the probe CLOSED! Needless to say, the scintillators were going crazy, picking up chunks of stuff through more than a foot of overburden in some cases. I took home a duffel bag of various specimens.
To determine what elements comprised the radioactive mineral, a close relative helped analyze them via characteristic x-ray emissions using his lab's scanning electron microscope. While the technique is not quantitative, it does show what is there in large proportion. This mineral contains niobium, uranium, titanium, iron, yttrium, and oxygen. Probably minor constituents include tantalum, neodymium, calcium, thorium, and scandium. On this basis, I believe the black mineral is either yttrocolumbite, uranopolycrase, or samarskite. More effort will be needed to be specific. I also took sand samples from Deep Creek, both above and below the point where the drainage from the mine area intercepts it. Have yet to look at that dirt. Right now they are being settled out in jars to filter out the uninteresting light sediments.
The photos below document this interesting and surprisingly rewarding trip. First shows Q and I at the collecting site. Second shows Q hauling out a pegger from ~16" hole. Third, a sample with a black vein and what it does to a CDV-700 on the highest range (probe closed, mind you). Third is from the SEM x-ray analysis. Note that while the heaviest elements such as uranium, this low-voltage-beam (20 kV) analysis is pretty insensitive and the peaks are small even though concentrations may be high. The uranium M peaks are labelled.
(Finally...I should put in a word of caution for any avid collectors who want to jump on this spot: please don't go in this area without asking relevant property owners. Most of the land that contains these pegmatites is private. Some of the old feldspar mines are exceedingly dangerous, where the slopes of the pits exceed the "angle of repose" and cave-ins have killed people.)
-Carl
I didn't relish the idea of panning for minute uraninite crystals in the frigid mountain stream itself. Before going, I tried to pinpoint outcrops that might have been responsible for the placer uraninite, including a bunch of granite pegmatites near Deep Creek that had been mined previously for kaolin and feldspar. I didn't find any reports of uranium or thorium from these, however, so I thought the chance of finding any radioactivity would be remote.
I picked up Q in "downtown" Bryson City (he lives nearby) and we went to work with scintillators on the sites I'd mapped out. One site, including the dump of the old Deep Creek No. 1 Feldspar Mine (35°27'12"N , 83°27'20"W), was amazingly, wickedly, radioactive--much to my surprise. Big lumps of a black, dense, very radioactive mineral line this dump in profusion. Much of this material will peg out a CDV-700 and some pieces will peg it with the probe CLOSED! Needless to say, the scintillators were going crazy, picking up chunks of stuff through more than a foot of overburden in some cases. I took home a duffel bag of various specimens.
To determine what elements comprised the radioactive mineral, a close relative helped analyze them via characteristic x-ray emissions using his lab's scanning electron microscope. While the technique is not quantitative, it does show what is there in large proportion. This mineral contains niobium, uranium, titanium, iron, yttrium, and oxygen. Probably minor constituents include tantalum, neodymium, calcium, thorium, and scandium. On this basis, I believe the black mineral is either yttrocolumbite, uranopolycrase, or samarskite. More effort will be needed to be specific. I also took sand samples from Deep Creek, both above and below the point where the drainage from the mine area intercepts it. Have yet to look at that dirt. Right now they are being settled out in jars to filter out the uninteresting light sediments.
The photos below document this interesting and surprisingly rewarding trip. First shows Q and I at the collecting site. Second shows Q hauling out a pegger from ~16" hole. Third, a sample with a black vein and what it does to a CDV-700 on the highest range (probe closed, mind you). Third is from the SEM x-ray analysis. Note that while the heaviest elements such as uranium, this low-voltage-beam (20 kV) analysis is pretty insensitive and the peaks are small even though concentrations may be high. The uranium M peaks are labelled.
(Finally...I should put in a word of caution for any avid collectors who want to jump on this spot: please don't go in this area without asking relevant property owners. Most of the land that contains these pegmatites is private. Some of the old feldspar mines are exceedingly dangerous, where the slopes of the pits exceed the "angle of repose" and cave-ins have killed people.)
-Carl