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Yttrium Fluorite

Posted by Kristi Hugs  
Re: Yttrium Fluorite
January 15, 2012 11:03PM
I am learning so much! wow! Yes, it does feel heftier in my hand. I don't know if it helps in the process if I share that I can shine a light through it, even though it is 1/2" thick or not? Does that help in the info for a determination or is that just, I can shine a light through it? :) I have attached the piece I used for the SG test and the same piece with light behind it.


PS, I am honestly so thankful that you scientific folks are being so patient with a non scientific folk like myself :)
open | download - yttrianunderlight.jpg (338.7 KB)
open | download - yttrianpossibly.jpg (440 KB)
Re: Yttrium Fluorite
January 16, 2012 03:54AM
As far as the SG calculations go, there is a slight error. In your examples, you were calculating the density of the sample using weight ounces and fluid ounces. This can give some erroneous results; converting weight (actually, mass) to grams and volume to cubic centimeters (cc) gives better results. In your first run, you measured the weight as 5.03 oz; this converts to 142.6 g (28.35 g/oz). The volume was estimated at 1.25 fl. oz., which converts to 36.96 cc (29.57 cc/fl oz). Thus the density of the sample is 142.6 g/36.96 cc, or 3.86 g/cc; dividing by water's density of 1 g/cc gives an SG of 3.86, which is *^^$ close to any value for fluorite, yttrian or vanilla. Not to shabby. Thing to remember with the kitchen measurements is that small errors in volume measurement can give large errors in calculated density, and thus the SG.

And this just for the heck of it. Seems that yttrian fluorite may be a "new find" for the crystal movement folk. Maybe because of all the recent interest in the rare earth elements and their seemingly magical properties; yttrium is considered to be on of them. Possibly someone in sales "discovered" this variety of fluorite in the literature, and decided it would help sales of otherwise boring fluorite. Of course, how to know that a given specimen is yttrian or not is beyond me. Also, it seems that the purported properties of yttrian fluroite may be different than reguler fluorite (otherwise, why distinguish them?). If so, if you buy a specimen hoping for the properties of the one, but actually have a specimen of the other, seems you would be subject to at least bad karma, or at worst like taking the wrong medication for some affliction. Just sayin'.
Re: Yttrium Fluorite
January 16, 2012 05:39AM
Thank you Doug.

Although I think you blew my brain up on the first paragraph, i think I followed :)

As for the second paragraph, as I giggle, I will say, point taken :)
Re: Yttrium Fluorite
January 16, 2012 06:21AM
Mira and all,

A few notes from a fluorite fanatic:

I bought some lapidary material called yttrian fluorite (rounded chunks, not slabbed) from a respected dealer in New Mexico; reportedly it's from Mexico. It's banded in light purple shades. I was hoping it would be fluorescent - other yttrofluorites in my collection fluoresce yellow under shortwave UV - but it doesn't glow. I'm assuming it's actually fluorite but haven't tested it, losing interest because of the lack of fluorescence.

A simple hardness test: if it isn't scratched by a copper penny (pre-1982) or a piece of calcite, but is scratched by a piece of apatite or a knife blade, the hardness is around 4 on the Mohs scale, so it could be fluorite.

A great reference book, Mineralogy for Amateurs by John Sinkankas, has instructions for building a simple but very accurate specific gravity scale out of a piece of balsa wood, some scrap lumber, a paper or cloth sewing measuring tape (metric), a single edge razor blade, a beaker, some thread and a paper clip - total cost maybe 5 bucks. The one I built is accurate to about 1%, using fairly small pieces of the mineral being tested. You might be able to find the book in a library, borrow it from a dedicated mineral collector, or buy it online at or It's well worth having, with tons of useful information including field collecting tips, mineral data, and lots more identification test equipment and procedures. Using its instructions, I also made a working calcite dichroscope (shows dichroic and pleochroic colors) and a polarizer (differentiates amorphous and cubic system samples from those that crystallize in other systems).

And now some philosophical content: In my deeply-considered opinion, there's no bad reason to love a rock...

Re: Yttrium Fluorite
January 17, 2012 03:16AM
Bill, I so totally agree with your philosophical statement :) and the rest too! thanks, it is really great info!!


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