FMF - Friends of Minerals Forum, discussion and message board

[norbie]

Hi. New user here (be gentle). I don't know much about mineralogy or chemistry so be patient with me :)

I recently became interested in minerals after I saw the exhibit on minerals and gemstones at the Smithsonian Institute in Washington DC. I've been purchasing books about minerals lately to learn more about them.

Today I have some questions about Beryl and the similar minerals in the Beryl Group and was hoping for some edification.

1. Emeralds and Green Beryl. Am I correct to think there are 3 different things that can cause Beryl to be green? I've seen a lot of websites and a few books give differing accounts for why emeralds are green. Some say an impurity of Chromium is the reason Emerald is green. Others say Vanadium is the reason Emeralds are green. Others say both are. Still others say the green in green beryl comes from a combination of Ferrous (Fe²+) and Ferric (Fe³+) Iron.

The way I have it figured out in my head is that the green that comes from the combination of Ferrous and Ferric Iron nor the green that comes from Vanadium qualify as true Emeralds and that only Green Beryl with an impurity of some Chromium qualify as true Emeralds. Am I wrong?

2. Has Violet, Purple or Magenta colored Beryl ever been discovered? I've seen some Pezzotattaite gems that appear Magenta but Pezzotattaite is just a member of the Beryl group and not true Beryl correct? I'm assuming any purplish Beryl would fall under Red Beryl.

3. Goshenite. Am I correct in my understanding that just because Goshenite is clear it does not mean it contains less impurities than the other varieties of Beryl? There are impurities that actually make it clear rather a lack of impurities that account for it being clear correct?

4. Maxixe Beryl. I can't seem to find much reliable info on this variety. What impurities accounts for the color (dark blue?) in Maxixe Beryl? I've seen sites say that the blue comes from a combination of Ferric and Ferrous Iron. I've also seen sites that say the blue comes from color centers

5. Indialite. I've read that Indialite is a species of the Beryl group. But it doesn't contain Beryllium. So why is it part of the Beryl group?

[alfredo]

Welcome to our forum!

In ancient times "beryl"/"emerald" were used for a variety of different gems, inconsistently. (There wasn't much concept of mineralogy as a science, or consistently identifiable mineral species, until the late 18th century). Later, "emerald" was confined to the bright green beryl gems, and Colombia (where the primary colour agent happened to be chromium, although no one knew that at the time) became almost the exclusive source.

It wasn't until the 20th century that some gem sellers tried to retroactively define emerald as beryls coloured by chromium - Not very logical, since the name "emerald" was already in use before the element chromium had even been discovered! Basically this was an attempt to maintain market share for Colombian emeralds and exclude competition from new sources that were coloured by vanadium, with almost the same spectral characteristics; in other words, a commercial scheme, not a scientific decision. And in reality many emeralds contain varying proportions of all 3 green "chromophores": Cr, V and Fe - all contributing to an infinitely variable palette of greens.

Indialite could be considered a member of a "beryl group" just because they have the same atomic structure, the same crystallographic structure, even though the beryllium is replaced by other elements.

I'll let others chime in re your other questions.

[gemlover]

Beryl is beryllium aluminum silicate (Be3Al2Si6O18). Different colors are caused by the presence of chromophores trapped in the crystalline structure. Bright Green is emerald (does not matter which impurity is causing the color); blue to greenish blue is aquamarine; yellow is golden beryl; yellow and brown is also called heliodor; pink to light purplish red is morganite; colorless (pure) is called goshenite. If a mineral does not have the correct base chemical composition it is not beryl.

I view this from a mineral, not gemstone, viewpoint. In the gem trade, some folk take exception to what an emerald is by chromium, vanadium, iron chromophore. However, all are sold as emeralds, usually with the country of origin given (Columbia, Brazil, etc.)

John

[John S. White]

I will add a bit to the discussion. Green beryls colored by iron have been synthesized but those that I have seen are not very attractive and it would be a stretch, in my view, to call them emeralds.

Goshenite often contains cesium and frequently the crystals are very tabular in habit instead of elongated. It is believed that the cesium is what dictates the tabular shape.

With respect to maxixe beryl, analysis does not show any impurity that can account for the blue color, so it is believed that the color is due to a color center, or structure defect, rather than an impurity.

I recommend Sinkankas's fine book "Emerald and Other Beryls."

[Pierre Joubert]

I have another fascinating book on Beryls 'Beryl and its Color Varieties - Lapis International', well worth having.

[norbie]

[norbie]

[Riccardo Modanesi]

Hi to everybody!
John, I agree with you: I read the magnificent book of John Sinkankas, it is really a work nobody can avoid reading!
According to what was said here about green beryls: I studied gemmology in Idar-Oberstein and they say: "no chrome, no emerald"! Therefore, if the double line in the red area of the spectroscope isn't seen, the green beryl is NOT an emerald. The green beryls whose colour is due to vanadium are simply called "vanadium beryls", as well as the red corundums whose colour is not due to chrome are called "red sapphires" or "pink sapphires", not rubies!
Greetings from Italy by Riccardo.

[John S. White]

I am afraid that I must disagree with Riccardo. Today most of the gem trade accepts as emerald any beryl that has an emerald color regardless of the cause of the color. If Idar-Oberstein is still teaching that the chromophore must be chromium then they are just about the only ones doing so. The first green beryls called emeralds were not from Colombia and they may very well have been colored by something other than chromium, so it seems unreasonable to try to attach this requirement to the definition at this point in time.

[Riccardo Modanesi]

Hi to everybody, hi John!
John, what I wrote is just a reportage of what is said in Idar-Oberstein, therefore it's not an opinion of mine! I would like somebody from Idar-Oberstein replies it, in order to clarify the argument.
I can tell you something more: who doesn't know the red variety bixbite, which is found in Nevada USA? You should know some 20 years ago it was sold as "red emerald" (sic!!!). We all must be very careful, because sometimes a scientific name could differ from a business name! For example I saw some citrine quartz sold as "citrine topazes" or, even worse, as "topaz vaiety citrine quartz" (boom!!!)!
Greetings from Italy by Riccardo.

[norbie]

[cyrille]

Hi

We have just been in Austria, where we bought and found beryl and emerald. We have visited one of the eldest emerald finder (Andreas Steiner).

He is the third generation of emerald and mineral collectors.

Perhaps you can visit his site, look for steiner bramberg , if you tell him the crazy dutchman has send you to him he will for shure answer the question about the beryl and emerald thing

[Riccardo Modanesi]

Hi to everybody, hi Cyrille!
I visited too the mines in Habachtal in Austria and, what is astonishing, not only emerald is found there, but also an intensive blue aquamarine and some crystals having a longitudinal half in green colour (emerald) and the other half in blue colour (aquamarine). Double-coloured beryls usually take their colour division along the pinacoide (horizontally in the normal crystal orientation), but the Austrian ones take this division along the prisma (vertically in the normal crystal orientation). That's why they are more interesting in my opinion.
Greetings from Italy by Riccardo.