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 Post subject: Feldspar Moonstone or Milky Quartz, or . . . .?
PostPosted: Thu Mar 23, 2023 2:21 pm 
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* background* I am new to gems and jewelery (long story), but decided this year I'd like to start settin my own stones and buying them onlline to sell in my gift shop. I had been doing lots of research and buying lots of cheap auction stones, when I added one in particular to my collection. It sold cheap at just $2, but when I looked at it, it took my breath away.

They called it a "Moonstone or Milky Quartz". It tested RI of 2.54 (and some odd hundreths, with a bit of bi-frigence turning the eyepiece). scratch test was roughly 6.5 to 7, although it didn't scratch glass as easily as quartz, quartz didn't really seem to scratch it.

It was a slight bit "milky", and showed brilliant lemon yellow flashes, with blazes of salmon orange and direct light showed a diffused yellow glow. Colors "popped" more in indirect light. Body color was white/clear. It reminded me of a sunrise.

So I bought more.

And more.

And more.

I couldn't stop buying them. They were like nothing I had ever seen. Each fully different, some with "fingerprint inclusions", some with "centipede" inclusions and some overall milky and some fully clear. All displayed the same color flashing, the milky ones showing a greater flash, and concealing a whisper glow of blue.

But NO ONE KNOWS WHAT THEY ARE. They tell me they are told they are milky quartz moonstone, I cannot find any actual 'rough" online yet, other than quartz.

Specific Gravity tests had a WIDE RANGE. 2.59-2.70 (from what I recall, notes not right in front of me). The color and milkiness seemed to not have an effect on SG.

My guess is more closely related to Laboradite than "moonstone", a Plagioclase instead of Orthoclase.

I have sent 3 different looking specimens in to be tested by GIA (asked specifically for x-ray diffusion so I know the mineralasis).

Anyone come across these and have more info? They all claim to come from one mine in Pakistan.

I have never seen quartz look like this. Dichroscope shows the same colors of yellow, orange and clear


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 Post subject: Re: Feldspar Moonstone or Milky Quartz, or . . . .?
PostPosted: Fri Mar 24, 2023 8:24 pm 
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First off: good on you for getting some tools and actually checking your stock!
This material is sometimes called 'girasol quartz' because of its resemblance to girasol opal, or 'moon quartz' or 'moonstone quartz' because of its resemblance to moonstone. It is an opalescent quartz. It is similar to opalescent 'lavender quartz'. Some opalescent quartzes get their opalescent effect from heat treatment, others have fine mineral inclusions which can also impart a star. I like this material, it has a unique look.

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 Post subject: Re: Feldspar Moonstone or Milky Quartz, or . . . .?
PostPosted: Sat Mar 25, 2023 6:21 am 
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Stephen Challener wrote:
First off: good on you for getting some tools and actually checking your stock!
This material is sometimes called 'girasol quartz' because of its resemblance to girasol opal, or 'moon quartz' or 'moonstone quartz' because of its resemblance to moonstone. It is an opalescent quartz. It is similar to opalescent 'lavender quartz'. Some opalescent quartzes get their opalescent effect from heat treatment, others have fine mineral inclusions which can also impart a star. I like this material, it has a unique look.



Thankyou Steven!

I had seen it called by many names, including Milky Quartz but not Girasol quartz (even though I understand them to be the same), although I had seen mention of this online, and rough was found under this name.

I am certainly glad I DO have equipment and researched how to test as I received my first 'fake" stone a week ago. A Large swiss blue topaz, 26 carats, fancy cut. Honestly, were I more experienced I could have known from the video, it lacked the normal color flash of a genuine stone (although I have heard many lab stones mimic real ones perfectly). Sure enough, it tested as glass, and the inclusions I had assumed were chips were actually gas bubbles, lol.

The seller refused to acknowledge it was fake, but did refund my money back.

I'm still waiting for my official GIA report . . . it's been 2 weeks now... worse than Christmas waiting for that report!

My question is, why can't I find anyone selling this mounted as jewelry? I can find it polished as pendants, but nothing faceted that looks close to the stones I have.

Have you seen lab reports on these stones to show it's actual quartz? I have seen only basic reports, but nothing that tests the mineralization of it.

Second question is, if it's quartz, what's an acceptable price per carat I should be looking at for buying it? Right now I'm averaging $1-$2/carat, about the same as Citrine or Amethyst.

Lastly, if it's quartz is it worth buying to collect? How much of this stuff is there?

And . . . if it test to be NOT quartz but a type of feldspar, what then? What is the value and is it worth collecting?

Either way, it's stunning and I can easily sell it at Christmas time in my gift shop, but I don't want to under price OR overprice anything I sell :)

Thankyou so much!


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 Post subject: Re: Feldspar Moonstone or Milky Quartz, or . . . .?
PostPosted: Sun Mar 26, 2023 5:46 am 
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I don't think so . . .

while the properties are VERY similar to quartz, there are a few key items worth noting that eliminate it as a possibility.

The stones all have refringence. Roughly +/- 0.005, and quartz (not even amethyst or citrine) does not have it.

I had actually been leaning more toward a variety of plagioglase, based on the colors reflected in the stone, the alkali feldspar reflect more of a bluish glow, while the Plagioclase feldspar reflect more of a salmon pink glow, due to the mineral composition in how they reflect back and absorb the light.
https://www.epigem.de/en-us/feldspar.html

That's one website going into nice detail about the varieties, there was a website I'll have to find that talks specifically about the Plagiouclase end..

Also, going back to the refractometer, by cheat book says this: (see attached photo)

The RI readings are similar for quartz and oligoclase , and my stones are reading on the highest end of the oligocase, but they have bifrigence within the specified amount noted.

OK, here is the VERY dry article on light and mineral composition of various feldspars in the "moonstone" family and how they are defined :) This is really what led me to believe it was a plagioclase

I'm hoping this week ( SHOULD) get my GIA test results back.


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 Post subject: Re: Feldspar Moonstone or Milky Quartz, or . . . .?
PostPosted: Thu Mar 30, 2023 12:13 pm 
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You do realize Swiss Blue topaz is irradiated colorless topaz. The GIA report would be 10x more costly than an irradiated blue topaz.


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 Post subject: Re: Feldspar Moonstone or Milky Quartz, or . . . .?
PostPosted: Thu Mar 30, 2023 12:48 pm 
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Looks more like cleverly faceted opalescent glass to me. I do not recall ever seeing a labradorite or variety of with that appearance. But I have not seen everything, I will admit.

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 Post subject: Re: Feldspar Moonstone or Milky Quartz, or . . . .?
PostPosted: Thu Mar 30, 2023 2:07 pm 
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glhays wrote:
Looks more like cleverly faceted opalescent glass to me.

Especially the 2nd pic with the yellow glow. The refractive index of opalescent glass can be very close to moonstone.

More info please. Specific gravity? Note any fracture surface? Inspection with magnification?

Our feldspar pages:
https://www.gemologyproject.com/wiki/in ... e=Feldspar

https://gemologyonline.com/feldspar.html


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 Post subject: Re: Feldspar Moonstone or Milky Quartz, or . . . .?
PostPosted: Thu Mar 30, 2023 8:57 pm 
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Barbra Voltaire, FGG wrote:
glhays wrote:
Looks more like cleverly faceted opalescent glass to me.

Especially the 2nd pic with the yellow glow. The refractive index of opalescent glass can be very close to moonstone.

More info please. Specific gravity? Note any fracture surface? Inspection with magnification?

Our feldspar pages:
https://www.gemologyproject.com/wiki/in ... e=Feldspar

https://gemologyonline.com/feldspar.html



All the stones have identical RI readings, loupe shows some to have thin whisper cloud inclusions, others "fingerprints" and others thin hairworm strands. I have about 100 thus far, and out of the 100 only maybe 5 have some sort of fracture.

Hardness is ALMOST as much as a quartz, just under. Mod Edit: Hardness tests ARE DESTRUCTIVE and should never he used for Gem ID

SG is the odd part, it's quite volitile. Stones will read anywhere from 2.55-2.72, with no rhyme or reason as to why (clarity doesn't seem to play a role). Stones are tested 4 times and if there is a difference I split it down the middle. All my quartz (citrine and amethyst) read identical with no variation.

Sure, it could be clever glass. But they have zero air bubbles, and why go to all that trouble? It certainly doesn't sell for much. I actually did buy a topaz that ended up being glass, but it was almost 30ct. I could tell as soon as I put it on the refractometer and it read 1.51 instead of 1.62. It was easily scratched by a citrine.

These don't seem to be coated, I have scratched at the sides and nothing. Unlike my pink topaz (that was a bad idea) . . .

I'm not a "rock energy hippie" or anything like that. I don't carry rocks in my pockets. But there was something different about this stone . . . I had to have it close to me all the time. They are almost spiritual . . . I always keep at least one sitting on my desk.

It's either a quartz or it's a feldspar, 100% certain of that. 95% certain it's a feldspar.

I've talked to the guys selling the 'rough" and the guys selling the stones, and no one has tested it. It doesn't sell for enough for them to bother I guess.


BTW, I'm not sure where the topaz talk stems from (I don't recall saying anything about topaz), but I do have some very lovely Skardu mine specimens in soft hues of champagne :) And a few irradiated London Blue stones ;)

We will see any day WHAT it actually is, I am literally holding my breath. It's supposed to be back to me by the 4th, so I would assume the report will be back to me sooner, maybe even tomorrow!

I will keep you posted :)


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 Post subject: Re: Feldspar Moonstone or Milky Quartz, or . . . .?
PostPosted: Fri Mar 31, 2023 11:53 am 
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Does glass have birefringence? (no...)

Does quartz have birefringence? (yes, even by the chart picture you posted, 0.009)

Birefringence - two RI's on different optical axis.

A gem giving an RI of 2.54? Probably a typo?

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 Post subject: Re: Feldspar Moonstone or Milky Quartz, or . . . .?
PostPosted: Fri Mar 31, 2023 3:59 pm 
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Perhaps lab equipment without training is more dangerous than no lab equipment?


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 Post subject: Re: Feldspar Moonstone or Milky Quartz, or . . . .?
PostPosted: Sat Apr 01, 2023 11:48 am 
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abeck wrote:
Does glass have birefringence? (no...)

Does quartz have birefringence? (yes, even by the chart picture you posted, 0.009)

Birefringence - two RI's on different optical axis.

A gem giving an RI of 2.54? Probably a typo?



Yes, my mistake 1.54, not 2.54


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 Post subject: Re: Feldspar Moonstone or Milky Quartz, or . . . .?
PostPosted: Sat Apr 01, 2023 12:03 pm 
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1bwana1 wrote:
Perhaps lab equipment without training is more dangerous than no lab equipment?



I didn't know it required training . . . it seemed pretty straight forward to me . . . do people actually pay money to try to figure this stuff out??


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 Post subject: Re: Feldspar Moonstone or Milky Quartz, or . . . .?
PostPosted: Sat Apr 01, 2023 1:44 pm 
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You're starting to sound a bit defensive, mom.

Do people pay money to learn how to properly use instrumentation and correctly interpret results?
The wise ones do. The professionals do. And, I believe most of the folks on our platform did.

Bear in mind that identification of an unknown is based on the elimination of possibilities based on the results of several tests. I always suggest when testing, not to "look" at the unknown before starting tests. I prefer to let the instruments determine what something is or isn't, not clouded by what I suspect it might be.

Order of testing for me:
Polariscope Reaction (check with coniscope to see if you can find an optic figure)
Refractive index (taken in several directions to determine the optic character of your unknown)
Specific Gravity
UV reactions
Hand held spectroscope (if you don't possess a Raman)
And finally microscopic observations


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 Post subject: Re: Feldspar Moonstone or Milky Quartz, or . . . .?
PostPosted: Sat Apr 01, 2023 7:31 pm 
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A good trained gemologist would not be doing scratch tests on a gemstone.

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 Post subject: Re: Feldspar Moonstone or Milky Quartz, or . . . .?
PostPosted: Sun Apr 02, 2023 6:18 am 
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glhays wrote:
A good trained gemologist would not be doing scratch tests on a gemstone.



A well trained gemologist certainly not. But they also wouldn't have cheap $1 gemstones either I'd imagine ;) I consider anything under $8 to be fair game for learning.

It wouldn't make much sense to learn how to analyze stones and set stones on high price specimens. Although it could be argued that high price specimens will produce truer results ;)


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