MT. ANTERO: HELIODOR & EUCLASE

MT. ANTERO, 14,269 FEET.

Mt. Antero, and neighboring Mt. White, are two of the more spectacular mineral collecting sites in Colorado, and in fact, in the entire U.S. Collectors, both amateurs and professionals, have been chasing beryllium minerals, but especially aquamarines, for decades (at an elevation exceeding 13,000 feet). 

Several years ago, after first arriving in Colorado Springs, I purchased at auction a bucket of material with an included note labeled "Mt. Antero".  It appeared that the material had been screened since the largest size particles were no longer than about 1.5-2.0 cm.  At any rate, I had not been to the Mt. Antero collecting sites at that time so decided that the bucket should be mine.

Like many good projects, time became a factor and I simply let the bucket languish in a garage storage area---until this fall!  One day I found the bucket, took a quick look, and decided that I needed to do some picking.  The results were: numerous small aquamarine fragments [a blue variety of beryl: Be₃Al₂(SiO3)₆], fragments of goshenite [clear colorless beryl], a few small phenakites [Be₂SiO₂], goethite after pyrite cubes, some terminated quartz crystals, lots of broken "milky" beryl and feldspar fragments, and a couple of very interesting specimens.

One surprise find was the appearance of a small broken crystal of heliodor, or yellow beryl.  As I understand the situation at Mt. Antero, heliodor is not all that common. This crystal is certainly not a gem piece as fractures and etching are abundant; however, it is an interesting find.  The yellow color seems due to the presence of Fe+++ (ferric iron).

 

SMALL PARTIAL CRYSTAL OF HELIODOR.  LENGTH ~ 1 CM.

 

The second surprise was a colorless, striated, "flattened", prismatic crystal with one end terminated.  I did not have the slightest idea about what name to give this enigmatic specimen.  So, I begin a search for minerals that might occur with beryl ruling out other clear minerals such as phenakite, quartz, topaz, fluorite, and bertrandite.  Finally, I examined the "Mt. Antero" section of MinDat.org and looked closely at the mineral photos.  Thus, I came upon a single photo of euclase and "hit the winner".  Although it appears to be rare at Mt. Antero, it has been collected and photographed.  I am far from a mineralogist; however, the distinctive shape of the prismatic crystal, along with the striations, have been imprinted in my mind!



 

TERMINATION OF EUCLASE CRYSTAL. WIDTH ~9MM.

 

I suppose euclase should not be unexpected since it is a beryllium mineral [BeAl)SiO₄)(OH)] and closely related to beryl.  In fact, euclase is the product of decomposition of beryl.

Any day collecting at Mt. Antero is a bonus day in your life and does not count against your life span!  Just be aware that numerous active claims exist, and afternoon storms, including lightening, are a distinct possibility.  Flatlanders should always acclimate themselves at a lower elevation before attempting the assent.



 

mike