Oh wow this is so cool this is one of the coolest things I have read in a while!

[conuly]

(Thanks, Siderea!)

The glass chalice, known as the Lycurgus Cup because it bears a scene involving King Lycurgus of Thrace, appears jade green when lit from the front but blood-red when lit from behind—a property that puzzled scientists for decades after the museum acquired the cup in the 1950s.

http://tinyurl.com/lm5jbbf

Comments

[steorra]

I used to have a piece of violin rosin that appeared green or red depending on how thick the layer you looked through was. If you looked through a thin layer, it looked green; if you looked through a thick layer, it looked deep wine-y red. I always found this puzzling, and really neat.

[conuly]

IT IS OMG THE WORLD IS FULL OF CAPSLOCKS!!!

[steorra]

Does that mean "I have some and I just checked and saw the phenomenon you're talking about, and it's really neat!"?

Not all of the violin rosin I've had shows this light effect; most of it, especially the lighter-coloured stuff, is some variety of brown/amber no matter how the light shines on it.

[conuly]

No, I think it's neat without checking. I don't play the violin. Though we used to have something like three of them for a while....

[steorra]

Ah, I see.

[steorra]

Also, I really want to know what the mechanism of the rosin phenomenon is, but I've never been able to figure out how to find out.

[conuly]

...

google no help?

[steorra]

A quick search before writing that comment didn't turn anything up. I think I've tried harder in the past and also not found anything. It's possible that I just haven't found the right search terms yet.

[steorra]

So, I was following up on the violin rosin thing again, as I do from time to time to try to figure out what was going on. (I rediscovered this post via a comment email while I was searching my email to see if I'd found and forgotten a solution, but this was all I found.)

I am wondering if what's going on with some violin rosin is actually the same effect as what's going on with the cup! I just read:

Some companies also add precious metals to their recipes—another choice to consider when shopping for rosin. It is not uncommon to see gold, silver, lead-silver, and copper added to rosin. These materials purportedly increase the rosin’s static friction, creating different tonal qualities.

Also, I'm kind of surprised that lead-silver isn't considered too dangerous to use. Rosin dust gets everywhere.

[conuly]

I'm astonished too.

[elenbarathi.livejournal.com]

Woot, that's amazing!