[Rockhounds] Beryl Pit Beryl

[pmodreski at aol.com]

I guess I've sure had my consciousness raised about the "Beryl Pit" locality.? Seems like this is indeed a well known location to lots of people on this list--my pardon, I was just showing my provincialty in not knowing where?it was.? (I would be curious to know the result if I asked a lot of the collectors here in Colorado mineral clubs if they know where the "Beryl Pit" is; I'll bet, almost none would--I'd be surprised if any did.??My impression is?that the Rockhounds listserv includes a much higher percentage of people than average, who travel all about the country (and Canada) visiting diverse collecting sites.

Back to the location and its beryl, the usual effect of radiation on beryl is to turn it yellow; I've seen this in beryl crystals from a number of places, including Maine and Mt. Antero.? The radiation knocks off electrons and converts Fe+2 (green color) to Fe+3 (yellow).? If the beryl contains pure Fe+2 with no oxidized iron at all, it's pure blue aquamarine; common beryl contains a little of the yellow-causing ferric iron, so it looks green.? When the yellow beryl is gemmy, that's heliodor.? I've seen specimens where a single beryl crystal is bluish-green at one end and, where it is in contact with some radioactive minerals, yellow at the other end.

Radiation by itself may not make feldspar red (radiation exposure is responsible for the blue color of amazonite), but when there are uranium- or thorium-rich mineral grains in the pegmatite, radiation damage to these minerals themselves, damaging and degrading their crystal lattice, often helps liberate the iron that is also present in these minerals or in other adjacent minerals, resulting in iron-stained patches and halos around them, and this can make the adjacent feldspar dark red from the liberated hematite.


Cheers, Pete Modreski



________________________________________________________________________
More new features than ever.  Check out the new AOL Mail ! - http://webmail.aol.com


--- StripMime Report -- processed MIME parts ---
multipart/alternative
  text/plain (text body -- kept)
  text/html
---