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 Post subject: allochromatic light
PostPosted: Thu Aug 20, 2015 4:56 pm 
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PostPosted: Thu Aug 20, 2015 4:51 pm Post subject: Re allochromatic light
AlBalmer wrote:
This brings up a not entirely unrelated question. I keep seeing references to "allochromatic light". I'm familiar with the use of "allochromatic" vs "idiochromatic" as causes of color, but what is "allochromatic light"?


Bill Hanneman wrote:
Other or different.

Allo- is just a prefix. Use it anyway you might choose.

Nevertheless, color varieties of allochromatic minerals are idiochromatic gemstones.

While I have no problems with the mineralogical classifications of allochromatic and idiochromatic minerals, I do not believe gemologists have any good reason to adopt it, for the reason it does not consider the existence of color varieties—the heart and soul of the gemstone trade.

I believe gemology would be far better off if students were simply taught to recognize that color varieties of allochromatic minerals are idiochromatic gemstones.

Once a student knows emeralds, aquamarines, rubies, and iolite are idiochromatic gemstones, such terms as “red emerald, and colorless iolite will be recognized as the oxymorons they are and will not even consider discussing them.


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 Post subject: Re: allochromatic light
PostPosted: Thu Aug 20, 2015 5:27 pm 
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I'm familiar with the mineralogical uses of the term, and I don't really care one way or another whether gemologists use it. I was simply curious about the use of the term in reference to the light which should be used for a dichroscope. I'll take a stab at answering my own question: It's a bombastic way of referring to white light.


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 Post subject: Re: allochromatic light
PostPosted: Thu Aug 20, 2015 6:57 pm 
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The only reference I've seen to it was written here by our old MOD Doos:
http://gemologyproject.com/wiki/index.p ... Refraction
Quote:
Wavefronts (Huygens' principle)

Light propagates from a single source in all directions just like a pebble thrown into a pond creates waves around the center of impact. These waves (the wrinkles in the water) are at a certain distance from one another (wavelengths). The direction of propagation is perpendicular to the wave, and the wave itself is named a "wavefront".

Similar to waves in water, light also propagates in one direction with associated wavefronts. All of these wavefronts are at a distance of one wavelength apart.
Allochromatic light has an infinite amount of wavefronts, all at different distances depending on the wavelengths.


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