34° 36' 26.9" N 115° 39' 47.5"W (WGS84) (Google Maps)
Bureau of Land Management
The New Method Mine (Hope Uranium Prospect) is a legendary locality at which to find boltwoodite, a hydrous uranium silicate. The mine is located a few miles NE of Amboy and is clearly visible to the west off of Kelbaker Road. I would recommend parking just off of the highway and walking up to the mine, as the access road is very rough and sandy. There are two open adits and a deep, unfenced shaft at this site, so be careful.
Small (a few millimeters long), acicular boltwoodite crystals are reported to occur with quartz, calcite, and deep-purple/black fluorite within vugs in limestone. I could not find any such vugs, nor even any signs of deep-purple/black fluorite, when I visited this locality. However, I may have found a piece of massive boltwoodite (the yellow-green upper-left rock in the samples picture below; need to find a Geiger counter to check). Finding nice crystals of boltwoodite may require more time to bust open limestone blocks than I had when I visited this locality. Despite this disappointment, the geology at this locality is quite interesting. The mine follows the contact zone between a syenite intrusion (the purple rock in the samples picture below; almost completely potassium feldspar!) and a (probably Paleozoic) limestone. There is a nicely formed endoskarn along the contact (the small white rock in the samples picture; note the white blebs within the purple syenite in the contact zone picture) that is comprised of plagioclase, diopside (?), and sphene. The exoskarn is rather cryptic; presumably, the fluorite and boltwoodite formed in the exoskarn, but I couldn't readily identify an exoskarn zone in outcrop. The endoskarn appears to be almost completely devoid of any potassium-bearing minerals, so the limestone and syenite must have swapped a lot of calcium and potassium. The lack of any potassium-bearing minerals in any kind of exoskarn zone is a little odd...
I highly recommend stopping by Amboy Crater when you visit this locality. A hike into the crater is definitely worthwhile.
|Site visited on 1/2/2015||Page created on 2/15/2015|