GPS Co-ordinates 34d 45m 00s North 117d 32m 59s West elevation 2852
This is one of the best places in Southern California to be on a moonless night with a good bright UV light. The landscape will literally come alive with green and orange florescence the second you turn on your UV light. The entire landscape will begin to glow. There is little need to wander around and search because all of the rocks are pretty much the same mix of Schelite a tungsten ore, Powellite a source of molybdenum and florescent Caliche.
HistoryScheelite is an important ore of tungsten which is a strategically important metal. Scheelite is named for the discoverer of tungsten, K. W. Scheele. Although most of the world wide production of tungsten comes from the mineral wolframite, scheelite is especially abundant in the US and provides the United States with most of its supply.
Scheelite is a popular mineral for collectors. It forms perfect tetragonal dipyramidal crystals that look very much like octahedrons. These pseudo-octahedral crystals are sometimes truncated with minor pyramids, but only on the top and/or bottom points of the crystal; giving evidence of their true symmetry. Other minerals that form pseudo-octahedral crystals similar to scheelite include wardite, anatase and powellite.
Powellite, CaMoO4, is isostructural with scheelite which is why it forms similar crystals. The two minerals form a series in which the tungsten of scheelite is substituted for by the molybdenum of powellite. Powellite fluoresces a yellow color while scheelite fluoresces a bright blue under short wave ultraviolet light. Of course since molybdenum can substitute for tungsten, some scheelite specimens will show a yellow fluorescence.
The crystals of scheelite can look like fluorite octahedrons which can also fluoresce. However, fluorite has perfect octahedral cleavage and a lower luster. Massive scheelite has often been mistaken for massive quartz, but then the fluorescence of scheelite is a dead giveaway.
Many prospectors for scheelite have made good use of scheelite's typically bright blue fluorescence by searching for scheelite deposits by night with ultraviolet lamps. Many old mines have even been reopened after examination of the mine shafts with ultraviolet lamps have proven that the ore is not quite yet exhausted.
From LA take the 14 north to Mojave. Take the 58 for 17.5 miles to the 395 at Kramer Junction. Precede south for another 17 miles to the Princess Pat mine road turn off (gps 34d45m44s north 117d28m29s west) and make a right. Go straight west for 4 miles and then follow the trail .9 miles to the mine. You should try to get there at sundown when you can still see and wait for it to get dark.
A recent Sierra Pelona Rock Club Field trip
My UV light leaves something to be desired but I think you will get a feel for the colors of the minerals. In normal light these look more like desert Caliche or ash.