Pictures plus physical and optical properties on a well formed crystal or cut gem would be easier to ID than a cabochon or rough stone or a possible multimineral rock. There are many people who post pictures asking for an ID… those who respond invariably give multiple answers. Not often that all of the answers converge on a consensus… There’s no substitute for an in person expert opinion. I am not an expert in gems, just someone who is pointing out the difficulties in definitively ID’ing any specimen…some of the responses you should find very helpful…RoyJohn’s response is a professional one…optical spectroscopy would also be very helpful for detecting chromium, iron and vanadium and in what estimated ratios… The original remark that I made about emerald hosting rocks being of proterozoic age did pertain to the Egyptian emerald deposits… my error in going on to Columbian type emeralds… sorry if that caused any confusion… so far as detecting trace elements such as chromium, XRF would be the cheapest way to look at the elemental constituents… hand held instruments have become widespread although still expensive… someone close by such as a professional gemologist may have one… limitations are that light elements such as beryllium, carbon; and silicon and aluminum, magnesium are beyond the abilityof hand held XRF machines to detect. …on the other hand, chromium, iron and vanadium are detectable…the presence of these elements are not specific to emerald but could lead towards that direction. Beryllium detection is difficult but can be done with chemical reagents and shortwave UV flourescence…If beryllium is present with chromium or vanadium, your specimen would most likely be emerald…
you have some measurements already but to really confirm emerald, those aren’t quite enough.
There are no Columbian emeralds, I think you mean Colombian. 
It’s not the first time it’s happened, I doubt it’ll be the last.
typo! you’re right that it’s not the first nor the last time!!! I don’t type well! Best wishes, please let everyone involved with a definitive ID when you make it… I’m interested as are the others… Thanks.
I’m not huge fan of the big four, I just know the difference between Canada and South America, but some one will.
yup…Colombia está en Sudamérica. Las emeraldas de Columbia no existens, sobre a Carolina del Norte…no se nada si hayen des emeraldas de Canada…de Colombia, . alli proceden las emeraldas Colombianas muy finas… Gracias!
Ei hätää, sinun täytyy rakastaa google kääntäjää, se tekee asioista niin paljon helpompaa. En ymmärrä espanjaa.
Time to stop this before we get too carried away 
to be serious, I found a reference that emeralds have been found in Nevada, Utah, Montana and Connecticut in the US, besides North Carolina… The Utah emeralds come from the Wah Wah mountains and Thomas mountain area which is the only source, at least to my knowledge, of red beryl… If there’s beryl, there will be a potential for emeralds… The Wah Wah/ Thomas mountains are S type rhyolites as far as I know… they are the “tin ryholites” derived from partial melting of continental crust with vapor phase enrichment of incompatible light elements…emerald and aquamarine have been found there also…There was another discussion on garnets… garnets, topaz, high temperature quartz- cristobalite/tridymite and cassiterite are associated minerals in tin rhyolites. I went to Grant’s Ridge in New Mexico some time ago to look for topaz and garnet… found very small dark red garnet and cristobalite in gas pockets in the rhyolite flow… too small except for micromount specimens… A reference to emeralds in Utah pointed out that they were opaque small crystals found in a pegmatite near a scheelite mine… that would indicate that if the material were to have crystallized at shallow depth pegmatite formation would have been more widespread instead of the material being ejected in volcanic eruptions… a reference to emerald in Nevada states that emeralds are found in Jackson Mountains in Pershing county, not much else… geology would be similar to Utah basin and range. I can’t find a good reference. Montana emerald is obscure… not confirmed with little else… Emerald also reported in Trumbull CT… these would be pegmatite hosted… There is a pegmatite at Haddam CT that produced multicolored beryls… I visited one of the Haddam quarries that was abandoned… pegmatite was there although just feldspar and mica was left from previous mining…Commercial mining of emerald is on going in Canada, east of Whitehorse in the Yukon… the deposit is similar to most world wide in that granitic/pegmatitic rock intruded into ultramafic rocks, the former providing beryllium, the latter chromium. The mining company Ture North Gems, also hit on another deposit in Northern Ontario…
So indeed there are “Columbia” emeralds if we are referring to North America as Columbia… took a bit of online digging to pull out the references.
please see my prior post about “columbian” emeralds… dug up some references… emerald is found in North America, at places other than North Carolina… commercial mining by True North Gems is exploiting Canadian Emerald deposits.
did you ever get a definitive answer as to what that stone is?.. let us all know when you have it… I’m curious about it, others most likely also… have a good day.
I have not yet, but should know soon. I got some other stones directly from an obscure secondary deposit in a region not well known for gemstones, and like this one, they were clearly worked, but not in ways recognizable in modern times. I am going to send them all in for testing and Im happy to update either way,
Thanks again for all the help and suggestions!
let me know what you have when you get it tested… your specimen is very very interesting… should let you know that to determine exact provenance, if indeed from ancient egyptian mines, only laser ablation inductively coupled plasma mass spectrometry will be able to tell. the technique is extremely senstive and precise and basically non destructive, as only a very small area of the surface is ablated… the cost for a run is very high…$50 to $150 per hour… both academic and commercial labs run specimens to defray the cost of having one…These machines are so sensitive they come close to counting individual atoms…for isotope gemochemistry, it’s the only way to separate out isotopes… isotope ratios can determine almost everything… Today I am on my way to Chicago to attend the annual Goldschmidt meeting of the joint geochemical and european geochemical socieities… data on asteroid Bennu which was sampled by NASA will be presented…
Tracing provenance of a single stone which may have changed hands over a thousand years and moved across continents does require LA ICP MS…it’s the only way that isotopic composition can be measured…isotopic signatures along with trace element signatures are highly specific for a single provenance… sometimes down to a single mine.
Good luck and let us know what you have… thanks, StevenH
I read about another test that I’m pretty sure is optical based, but uses an FFT algorithm (Fast Fourier Transform) so that highly sensitive optics and other components are not needed (ie, it’s cheaper). I will try and find the exact name of the instrument but it’s a mass spectrometer of some kind. If you are not familiar with FFT and curious about breakthrough innovations, that’s one you may want to look up. I’ve used it in digital audio use-cases to essentially reproduce a lossless digital signal from a partial, low res analogue sample, so it makes sense that it could be used similarly with light waveforms. It’s probably out of scope of this forum to cover FFT in detail, but the authors of this algo should have received a Nobel prize, it’s that significant.
Are you (or is anyone) familiar with the use of FFT based mass spectrometry to ID the “signature” of the mineral content of atonea to ID and geolocate?
FFT is well know to me… I used FFT analysis daily in my own work before I retired… brain waves are are sinusoidal and can be reduced to component sine frequences to obtain frequency/power spectra over time… integral analsis within a set interval of time. Fourrier mathematics are not too difficult to understand as it’s trigonometry based with integral analsis within a set interval of time… This technique is suited for sinusoids or repetitive functions.
in audio, it can break down frequencies into component frequencies and reduce noise prior to AD conversion, but mostly prior as digitizied data is what is fed into a computer to do the math. I think what you are refering to is the use of it in conjunction with optical spectrometry. It can sharpen absorption peaks from broad bands into discrete absorption lines, which helps at lot if there are multiple overlapping broad peaks. FFT has been used for decades… radio, audio, anything with periodicity… Higher energy photons, in the soft x ray band, as with XRF do not need as much preprocessing as the energy jumps are greater and and discrete.
LA ICP MS works on a different principle…it works by mass to charge ratios…for a given charge, a heavy atom has more momentum and is turned less in a magnetic field than lighter ones… it detects trace element abundance and graphs it against a standardized set of trace elements. It is also the only means that isotopes can be separated… isotope ratios of both stable and radiogenic elements with their decay products trace age and geochemical cycling…the variance from a standard gives valuable geochemical data. An example is the from eND, radiogenic Nd/Sm, Rb/Sr, and the more complicated Ur/Pb and Th/Pb systems not only date very ancient minerals (zircons in particular) but also tell us that the earth’s crust and mantle have been recycled about 6 titmes over the entire history of the earth. Improvements in mass spect are now centering around time of flight… as ions are accelerated in an electric field, heavier ones move slower, for the same amount of charge they carry…isotopic separation increases. Ions are singly charged, by designs so mass to charge ratios are stable.
Since geologic processes cause element partition based on their electronic structure that determines their chemical bonding, tracing mantle sources to crust can be done…elements are partitioned and isotopes also…with heavier isotopes being less mobile than lighter ones… isotopic separation determines not only age, but also partitioning…Provenance of individual mineral grains can be traced as some have nearly unique isotopic and trace element signatures, reflecting in fine detail the geologic processes that created them…