[Rockhounds] Why does the color of some gems fade?

[jerrybs at frii.com]

Some of the opal, opalite, etc will loose their blue color when they dry
out.  I've also seen this in thundereggs.

Jerry
WA



> Carol Carter-Wientjes wrote:
>>
>> Hi Rock Friends,
>>
>> Just back from a trip to Oregon and a first sunstone dig. What fun! We
>> didn't find anything to retire on but did recover a couple lbs. of small
>> schillers and a few little reds. Easy to see why people get hooked on
>> digging them, count me in!
>>
>> On to the question.....Why do some pink and purple gems fade? ie, rose
>> quartz, Holley Blue, etc. How about carnelian too? Does it make a
>> difference if they're heat-treated?
>>
>> Looking forward to your comments on this, CaroL
>
> Sunlight provides the energy needed to change crystal structure at the
> molecular level and alter the properties of many colored crystals.
>
> Kreigh
>
> --