[Rockhounds] Heliodore - gold beryl

[Axel Emmermann]

Hi Werner,

I'm not a professional geologist like Pete, so please treat my answer with
the necessary discretion ;-)

I believe that Heliodore is a variety of beryl that is typically colored by
the presence of iron. More specifically the charge transfer between iron and
oxygen.
Some sources state that heliodore may also be colored by uranium in rare
cases. 
( http://socrates.berkeley.edu/~eps2/wisc/Lect9.html ) 

Personally I would be inclined to use the same criteria that are used for
other gemstones.
Ruby has quite a broad pallet ranging from deep red-brown (some Fe present)
over almost purplish red to bright red and even pink. But all corundum that
is colored some shade of red by chromium 3+ replacing Al 3+ is called ruby.
There is no fixed criterion although value depends largely on transparency
and color.

I think it would be acceptable to do the same with heliodore. If a beryl is
colored 
1) sufficiently deep yellow 
2) by the presence of iron 
3)to be distinguished from other varieties by the unaided eye 
then I'd have no trouble calling it heliodore.

Since heliodor is NOT a mineral but rather a variety name I wonder if there
even are any established criteria for it to earn the name other than being
yellow. 

About the "golden beryl": I'm always careful with adjectives that precede a
gem... They usually are meant the "embellish" a plain stone ;-)))
For example:
Bohemian ruby = pyrope garnet
Bastard emerald or evening emerald = peridote
Lithia emerald = hiddenite
Bohemian or golden topaz = citrine
Smoky Topaz = smokey quartz
Sachsen (Saxony) Beryl = apatite

I hope this was helpful

Axel Emmermann 
European Regional Vice President of the 
Fluorescent Mineral Society 
<http://www.uvminerals.org/> 
========================= 
Mineralogische Kring Antwerpen/Antwerp Mineralogical Society 
<http://www.minerant.org/index.html> 
Werkgroepleider/Workgroup leader: Fluorescerende mineralen/Fluorescent
minerals
Technische Realisaties/Engineering 
My website:<http://users.pandora.be/axel.emmerman/home/>