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Yttrium Fluorite

Posted by Kristi Hugs  
Re: Yttrium Fluorite
January 14, 2012 03:51PM
Thank you for your information Doug. I must tell you, as a "touchy feelie" I am dedicated to sharing both geological and "touchy feelie" information, which is why I am here, to get the facts. It is interesting to me that the fluorite with yttrium in it is called Yttrian. Why not just call it what it is? Here in lies my confusion I suppose. I have attached a picture in the post previous to yours so that you can see what this fluorite looks like.
avatar Re: Yttrium Fluorite
January 14, 2012 04:03PM
    
Mira Bai Wrote:
-------------------------------------------------------
> It is interesting to me that the fluorite
> with yttrium in it is called Yttrian. Why not just
> call it what it is?

Yttrian is an adjective meaning "containing yttrium". Calling it "yttrian fluorite" IS calling what it is. Calling it "yttrium fluorite" is not.
Re: Yttrium Fluorite
January 14, 2012 04:35PM
Awesome! thank you!
avatar Re: Yttrium Fluorite
January 14, 2012 05:48PM
    
Mira,

Mindat and most geologists use mineral names approved by the International Mineralogical Association. You will notice the date on the above reference paper is 1958. Most copies of Dana's System of Mineralogy are also dated prior to 1960. The name "yttrian fluorite" was discredited during the 1960s and replaced with "yttrofluorite".

I have 2 references to the Browns Canyon district, and pictures of similar material I have collected there, but am hesitant to post them. You may be happier not knowing the whole story.

-Dean Allum
Re: Yttrium Fluorite
January 14, 2012 06:01PM
Hey Dean,

Thank you for the info. I am in contact with the vendor to see if they were just cut/sliced by someone in Colorado and are from some other place or if they were cut, as in mined, in Colorado. I am not clear on that just yet :)

I guess I am different from your average touchy feelie......I want to know the truth, the whole truth and nothing but the truth when it comes to geological info, so give it to me :) I can handle it :) I am far more concerned about having integrity that I am giving half of the truth :)

thanks for your post. It is very helpful!

Mira
avatar Re: Yttrium Fluorite
January 14, 2012 11:24PM
    
Mira,
Below is the relevant text from two books.

'Colorado Rockhounding' by Stephan Voynick 1994

page 65: "The Browns Canyon fluorspar-mining district, eight miles northwest of Salida, covers six square miles between the Arkansas River and U.S. Highway 285. Between 1929 and 1950, Browns Canyon ranked among the top U.S. fluorspar districts, with twenty mines producing over $5 million in fluorspar. Fluorite mineralization occurs along a four-mile-long fault section as veins of fluorite associated with chalcedony; accessory minerals are barite, calcite, pyrite, iron and manganese oxides, and small amounts of opal. Browns Canyon fluospar ores are white or gray, with light shades of red, brown, and green. The fluorite, mostly botroidal and nonfluorescent, ranges in color from pink and yellow to green, purple, and white. Nodular growths, with fluorite forming concentric bands around breccia fragments, also occur. In the 1950s, lapidaries cut and polished nodular specimens into attractive display pieces"


'Minerals of Colorado' by Edwin Eckel 1997

Page 210: "Browns Canyon District. This district, which has produced large quantities of fluorspar, is 8 miles northwest of Salida and lies between the Arkansas RIver and U.S. Highway 285. The fluorite occurs as veins in granitic and volcanic rocks. Most is white and fine-grained. It occurs as bands along faults and as large irregular masses that are botroidal, mammillary, or even stalactitic. At the Morgan Ranch deposit, veins of fluorite, ranging from a few inches to 4 feetin width, cut granite and the overlying lava flows. The fluorite is fine-grained and porcelanic to sucrosic textured and is beautifully banded in shades of green, pink, purple, red, brown, or white. The fluorite deposits now incorporated in the Browns Canyon Wilderness Area were reviewed by Leibold and others (1986)."

Page 215: "Yttrian Fluorite from the White Cloud pegmatite occurs in large anhedral cleavage masses up to several feet across. The yttrian fluorite is present between the intermediate zone and the core of the pegmatite with synchysite-(Y) and other REE minerals. ... Simmons and Heinrich and Wayne discussed the occurrence of yttrofluorite and the REE mineralogy of the White Cloud pegmatite. The fluorite is typically opaque, pale tan in color and has a distinctive pinkish white fluorescence under SW UV."



On the left are two purple banded silicified fluorite slices from the Browns Canyon district. They have a specific gravity of 2.97 My lighter material is covered with snow right now.
On the right are two brittle, ugly euhedral yttrofluorite crystals from the White Cloud pegmatite. They have a specific gravity of 3.24, are radioactive and contain synchisite or bastnasite inclusions. They would not make nice jewelry.

-Dean Allum
Re: Yttrium Fluorite
January 14, 2012 11:37PM
Thank you Dean!!

This information is good to know!! I have seen the silicified Fluorite before. It was sold to me as "Tiffany Stone". Nice to know what it really is! Very good to know about the radioactive stuff too! LOL I am waiting to hear from my vendor to see if this stuff came from Colorado and if it has been tested.

So here is a question for you. Is light able to be seen through the silicified Fluorite? Would light be able to be seen through Yttrian Fluorite? Is there a difference in hardness? (I am thinking silicified would be harder than the soft Yttrian? Sorry if my terminology sucks......I am learning slowly :)

thank you so much for taking the time to post this for me. I am truly appreciative!!!

Mira
Re: Yttrium Fluorite
January 15, 2012 12:09AM
Mira,

If you've been posting for 5 years apparently you can take it. I like dependable dealers too, but you can understand the skepticism you were hit with, can't you, when your trusted authority is in the business end of this field, not academic, and also hasn't put you wise to the correct name of what you bought?
If you can get a good approximation of the minerals' SG, you can really be satisfied. The SG of agate is what, 2.6? Fluorite3.2, and yttrofluorite, "up to 3.6" (Dana's) With a digital scale and some kitchen equipment you can at least come close, unless there is matrix...
I thought Dan and Stephanie were most helpful, too. Put me wise, so thanks for bringing this subject up.

Mike
Re: Yttrium Fluorite
January 15, 2012 12:14AM
Hey Mike,

Yes, I can take it and yes, you are correct, I do understand the skepticism. I know if I mentioned the names, they would probably understand why I am so sure that this stuff is legit, but don't want to bring up names, ya know? Then again, if I am wrong and I bring up the name, then that would not look good either :) Not sure that makes sense, but anyway.....

I have a digital scale and a kitchen full of equipment. How do I get a relatively close SG?

Dan and Stephanie were most helpful. Dean too :)
Re: Yttrium Fluorite
January 15, 2012 06:28AM
Yes, makes great sense.
If I understand it right, weigh the piece grams or ounces, lets say ounces, on a scale, then submerge it in water in some clear, calibrated measuring cup, and find how much volume it displaced. if you put that piece in 8 ounces of water, and then the water went up to 10 ounces, that piece's volume is two ounces. if your scale read a weight of 7 ounces, let's say, then your SG is 3and1/2, about what y-f would be. If the scale weight was, say, 5. 4 ounces, your SG is closer to 2.7, like quartz. The problem is getting the volume accurately enough, because fractions of an ounce you could be only estimating. A jolly balance is a more accurate scale for SG, if you have the use for it.
So it is a ballpark figure, not exactly high-tech.
If anyone else has a better idea or procedure on SG, I'm all ears.
So does THIS make sense?!

Mike
Re: Yttrium Fluorite
January 15, 2012 05:24PM
I weighed the piece. It is 5.03 ounces.
I placed this piece in 10 oz of water. It went up one hash mark. Maybe just a tick above.

15

-

--

- <----- once the piece was placed into the water, the water went up to here. So that would be 11.25 ounces

10

So 1.25 is the volume. correct? (11.25 - 10 =1.25)
and 4.02 would be the SG? (5.03 divided by 1.25 = 4.02)

Sorry, I am bad at math :) is that close?

thanks!!
mira



Edited 5 time(s). Last edit at 01/15/2012 05:58PM by Mira Bai.
avatar Re: Yttrium Fluorite
January 15, 2012 06:23PM
    
Hi Mira,

In order to get an accurate reading, the specimen must not touch the sides or bottom of the vessel, it must be suspended in the water, usually using a thread or string or such.

regards,
stephanie smiling smiley
Re: Yttrium Fluorite
January 15, 2012 06:35PM
OK! good to know :) I will try it again :)
Re: Yttrium Fluorite
January 15, 2012 07:20PM
Mira,
For a guesstimate, that looks pretty good. You can skip the '.02' because this is only a ballpark figure. but that is heavier than I expected, so I'm at a loss to explain it. Maybe try it w/ something you know the SG of that is pure, one minerl, and see if you come close the established SG. Either way, have fun sleuthing.

Mike
Re: Yttrium Fluorite
January 15, 2012 07:34PM
Hey Mike,
Stephanie suggested that I tie a piece of string and suspend the piece, instead of just letting it drop to the bottom. I am going to try again using that technique and see if it will improve (give more accurate) the numbers. Stay tuned!

mira
Re: Yttrium Fluorite
January 15, 2012 07:47PM
Ok, well the string tieing experiment came up like this:

I used a slab that weighed 2.5 oz
The slab itself measures 2 1/4" x 1 3/4" x 1/2"
I used 20 oz of water as I wanted to make sure the piece was submerged in the middle by the string and not touching the bottom or the sides.
The water only moved up 1/2 of a hash mark (each hash mark = 1.25 oz, 1/2 of a hash mark would be 0.63) which would make the 20.63

So, using these new figures,
the volume is 0.63 (20.63 - 20= 0.63)
and 3.97 would be the SG (2.5 divided by 0.63 = 3.97)

I must be doing something wrong....how could the SG be more than the weight of the specimen? Maybe I need a cup with more accurate markings. Hmm, maybe I should find one of those jolly things........LOL
Re: Yttrium Fluorite
January 15, 2012 08:30PM
Fluorite sold as "yttrium fluorite" that looks sort of similar to your material has been analyzed by X-ray Fluorescence Spectroscopy (XRF) and no yttrium was detected. See [theodoregray.com] I don't know the detection limit of this measurement, but it's certainly lower than 20%. That's not to say that your sample contains no yttrium for sure, but I would suspect it doesn't.

Purple color in fluorite is commonly attributed to "color centers" - defects in the crystal structure consisting of (in this case) a free electron sitting where a fluoride ion should be in the lattice. See [gemologyproject.com] for more info. This is probably the cause of color whether your fluorite contains yttrium or not.

As for specific gravity, it's definitely OK for it to be larger than the weight of the specimen, since it's measuring something different than weight. Specific gravity is a measure of density, how much a given volume of a substance weighs. Density is specific to a material; for example, a 1 cm cube of gold would weigh 19.3 g, and a 10 cm cube of gold would weigh 19.3 kg, but both would have the same density, because both are made of gold. Even a small flake of gold weighing only a few mg would still have this same density.

Therefore, Mike's suggestion to use some standards makes a lot of sense. Any sample of quartz, or iron, or copper, or aluminum, etc. should have the same density and your measurement can be compared to the known density of these materials. Good luck with the measurements!

(As an aside, density depends on the units you use for weight and volume. In this case, you used ounces and fluid ounces, so your density is in units of oz./fl. oz. Specific gravity is density relative to the density of water, which is 1 g/mL or about 1 oz./fl. oz., so the units you used do give a measure of SG)
avatar Re: Yttrium Fluorite
January 15, 2012 09:47PM
    
Mira,
While I am calling the rock from Browns Canyon "silicified fluorite" it is actually a sedimentary mixture of fluorite and chalcedony. It has a specific gravity between the two. It is only translucent when it gets as thin as ~2mm. While it is hard enough to act as jewelry, it is soft enough to smooth and polish with wet sandpaper.

My yttrofluorites have had their crystalline structure destroyed by their radioactivity and are not transparent at all.

You should be commended for attempting to make specific gravity measurements. This is a relatively easy way to help identify specimens. I don't think you have been given enough info here to make an accurate calculation. Please refer to this earlier thread about it. Most S.G. methods are based on the fact the water has a density of 1.0 gram per cubic centimeter.
Specific Gravity Thread

Good Luck,
-Dean Allum
Re: Yttrium Fluorite
January 15, 2012 09:50PM
Thanks everyone!! This has certainly been educational! I don't know how or where to get a piece tested, or even how much something like that would cost, but I am relatively sure I have enough information to somewhat accurately describe the specimens to my customers. You all have been very very helpful! Thank you!

Mira
Re: Yttrium Fluorite
January 15, 2012 10:50PM
You are still more or less at SG of 4, so I'd go w/ that. But if quartz materials are @ 2.6, and ytt-fluorite is 'up to 3.6 SG', you have something else in the mix, it would seem to me.
1 oz. volume of water is, well, one ounce weight! (Wow, there is a revelation!) So w/ quartz, 1 oz. volume of quartz. is 2.6 ounces, wt. A cup (the usual 8 oz. glass of water) is half a pound, right? so a cup of quartz would be 20.8 ounces in weight. Get my drift? (Gold, at SG 19, one ounce wieghs 19 ounces, etc....
I found a blocky hunk of chert in a stream bed that weights in near 21 pounds. a gallon of water is 8lbs.,(2.6X}= 20.8lbs, so i call the piece my "gallon" of chert.
So your piece is heavier than your average stone of that size. It should feel 'heftier' in your hand
I appreciate Noah's explanation of the free electron in the fluoride spot in the lattice. That helps.

hope this helps,

Mike
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