<p>The answer to your question is probably the second:</p>

<blockquote>
  <p>Or do REEs only <em>modify the color</em> of their fluorescence, but not necessarily cause it?</p>
</blockquote>

<p>I will give an example of apatite. Here's a cathodoluminescence (luminescence excited by electrons) energy spectrum of a natural apatite. <a href="https://doi.org/10.3749/canmin.1800021" rel="nofollow noreferrer">Source</a>.</p>

<p><a href="https://i.sstatic.net/PYzYK.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/PYzYK.png" alt="enter image description here"></a></p>

<p>You can see several different rare earths triggering the luminescence, but there's also manganese. Apatites from granites usually have lots of manganese, and very little rare earths. So their luminescence would be dominated by the 2.1 eV range, which would be <a href="https://www.wolframalpha.com/input/?i=2.1%20eV%20to%20photon%20wavelength" rel="nofollow noreferrer">yellow</a>. In contrast, apatite from REE deposits would be dominated by Ce, giving a <a href="https://www.wolframalpha.com/input/?i=3.0%20eV%20to%20photon%20wavelength" rel="nofollow noreferrer">blue-violet</a> colour. They will also have lots of Nd, but that does not help us because it's in the infra-red range.</p>

CC BY-SA 4.0
2021-01-15T23:52:58.397Z
Somehow I missed the notification for this answer, this is beautiful, both graphically and as a multiparameter fit. I'd heard of cathodoluminesence used in semiconductor device analysis but have never seen it used in minerology(?) I'll try to grab a copy of this paper and have a look. *Thanks!*
uhoh
CC BY-SA 4.0
2020-02-24T03:51:18.257Z
2020-02-24T03:51:18.257Z
Gimelist
<p>No it is not by chance. As an ion, rare-Earth metals and compounds behave like alkaline Earth metals, so they form near each other. For example, neodymium has similar chemical properties to barium. They can both modify and cause fluorescence in calcite and/or fluorite.</p>

CC BY-SA 4.0
2024-01-26T18:57:06.153Z
2024-01-26T18:58:40.183Z
2024-01-26T18:58:40.183Z
Lalith_Aditya
<p>If I understand <a href="https://earthscience.stackexchange.com/a/18581/6031">this answer</a> and <a href="https://earthscience.stackexchange.com/questions/18549/can-i-just-walk-around-greenland-with-a-uv-light-and-find-rare-earth-minerals-on/18581?noredirect=1#comment40159_18581">this comment</a> correctly, minerals like calcite, fluorite, and apatite are "commonly associated with (Rare Earth Element) REE deposits", and like some REEs also fluoresce when exposed to UV light. But the intrinsic fluorescent properties of those minerals are not caused by REEs.</p>

<p>Is this just a pleasant coincidence; the presence of one fluorescent mineral is often associated with the presence of another fluorescent mineral even though their fluorescence mechanisms are different?</p>

<p>Or do minerals like calcite, fluorite, and apatite tend to fluoresce <em>because</em> they contain REEs, thus observation of their fluorescence is a direct indicator of the presence of REEs? Or do REEs only <em>modify the color</em> of their fluorescence, but not necessarily cause it?</p>

<mineralogy><rare-earth><fluorescence>
Is the association of fluorescent minerals calcite, fluorite, and apatite with fluorescent rare-Earth minerals a coincidence?
uhoh
# Is the association of fluorescent minerals calcite, fluorite, and apatite with fluorescent rare-Earth minerals a coincidence?

(Asked by: username_0 on 2019-11-27)

If I understand [this answer](https://earthscience.stackexchange.com/a/18581/6031) and [this comment](https://earthscience.stackexchange.com/questions/18549/can-i-just-walk-around-greenland-with-a-uv-light-and-find-rare-earth-minerals-on/18581?noredirect=1#comment40159_18581) correctly, minerals like calcite, fluorite, and apatite are "commonly associated with (Rare Earth Element) REE deposits", and like some REEs also fluoresce when exposed to UV light. But the intrinsic fluorescent properties of those minerals are not caused by REEs.

Is this just a pleasant coincidence; the presence of one fluorescent mineral is often associated with the presence of another fluorescent mineral even though their fluorescence mechanisms are different?

Or do minerals like calcite, fluorite, and apatite tend to fluoresce *because* they contain REEs, thus observation of their fluorescence is a direct indicator of the presence of REEs? Or do REEs only *modify the color* of their fluorescence, but not necessarily cause it?

**Tags:** mineralogy, rare-earth, fluorescence


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## 2 answers

### Answer by username_1 on 2020-02-24. Score: 2 | Accepted answer

The answer to your question is probably the second:

> Or do REEs only *modify the color* of their fluorescence, but not necessarily cause it?

I will give an example of apatite. Here's a cathodoluminescence (luminescence excited by electrons) energy spectrum of a natural apatite. [Source](https://doi.org/10.3749/canmin.1800021).

[![enter image description here](https://i.sstatic.net/PYzYK.png)](https://i.sstatic.net/PYzYK.png)

You can see several different rare earths triggering the luminescence, but there's also manganese. Apatites from granites usually have lots of manganese, and very little rare earths. So their luminescence would be dominated by the 2.1 eV range, which would be [yellow](https://www.wolframalpha.com/input/?i=2.1%20eV%20to%20photon%20wavelength). In contrast, apatite from REE deposits would be dominated by Ce, giving a [blue-violet](https://www.wolframalpha.com/input/?i=3.0%20eV%20to%20photon%20wavelength) colour. They will also have lots of Nd, but that does not help us because it's in the infra-red range.

> **Comments:**
> **username_0**: Somehow I missed the notification for this answer, this is beautiful, both graphically and as a multiparameter fit. I'd heard of cathodoluminesence used in semiconductor device analysis but have never seen it used in minerology(?) I'll try to grab a copy of this paper and have a look. *Thanks!*  

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### Answer by username_2 on 2024-01-26. Score: 2

No it is not by chance. As an ion, rare-Earth metals and compounds behave like alkaline Earth metals, so they form near each other. For example, neodymium has similar chemical properties to barium. They can both modify and cause fluorescence in calcite and/or fluorite.


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