Wyoming Rocks

Pacer Pegmatite

The fluorescent minerals at the Casper Mountain pegmatite are mineralogical mutts. They are comprised of admixtures of quartz, albite, and small trace amounts of other pegmatite minerals that gradually grade into each other. Few large, distinct crystals are found.

Not too interesting mineralogically. But when they butt up against a serpentine contact, some of these mutts become beautifully fluorescent.

  • uranyl ions light up fractures and coatings a brilliant green
  • bright yellow originates with fluorapatite
  • some feldspar fluoresced a dull red
  • and unknowns fluoresce blue, purple, yellow and white

Casper Mountain Serpentinite

Vugs in highly altered serpentinite, contain calcite and other carbonates that are unusually beautiful, both in natural light and under ultraviolet light.

These Casper Mountain specimens are unusual. They are both bright, for calcite, and pastel in color.

Colors range from white to blue through red. Bright fluorescent green uranyl coatings and fracture fillings add to the mix. And caliche fluoresces toward the red end of the spectrum for added contrast.

The carbonates are highly phosphorescent with colors from tan, to blue white and dull green. The dull green fades after a few minutes, leaving a bright blue white phosphorescence that can be seen 15 minutes later.


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