Lycurgus Cup and its mysterious glass

[Hod]

I came by the Lycurgus Cup in some research my wife was doing and found it curious that the topic hadn't been brought up here--since it seems to be an ancient mystery that is still a mystery. I did a search and didn't find any posts on this site about it, but if I missed an already existing thread, by all means close this one.

From Wikipedia:

Quote

The Lycurgus Cup is a 4th-century Roman glass cage cup made of a dichroic glass, which shows a different colour depending on whether or not light is passing through it; red when lit from behind and green when lit from in front.^[1] It is the only complete Roman glass object made from this type of glass,^[2] and the one exhibiting the most impressive change in colour;^[3] it has been described as "the most spectacular glass of the period, fittingly decorated, which we know to have existed".^[4]

From the Smithsonian Magazine:

Quote

When various fluids filled the cup, Liu suspected, they would change how the vibrating electrons in the glass interacted, and thus the color. (Today’s home pregnancy tests exploit a separate nano-based phenomenon to turn a white line pink.)

Quote

The mystery wasn’t solved until 1990, when researchers in England scrutinized broken fragments under a microscope and discovered that the Roman artisans were nanotechnology pioneers: They’d impregnated the glass with particles of silver and gold, ground down until they were as small as 50 nanometers in diameter, less than one-thousandth the size of a grain of table salt.

It seems that we have been able to replicate the effect, but none of our modern attempts have been able to replicate the high quality of dichroic glass found in the Lycurgus Cup.

It seems like this might be a great example of the technological superiority of the ancients over modern man. Disclaimer to previous sentence: At least the one ancient man who created it, and in one very specific ancient technology (dichroic glass).

Edited August 21, 2016 by Hod

[ChrLzs]

Forgive me for being a devil's advocate here.. but if this was an example of something other than a happy accident, why aren't there lots of other examples from that time/region?

By a happy accident, I mean that its existence could be explained by the accidental addition/contamination of the right amount of an impurity such as a metallic oxide powder.  This is *not* necessarily an example of some sort of nano-technology or precision grinding, but is much more likely to simply be a deposition of a powdery 'scale', possibly even from a simple chemical reaction/electrolysis or similar (and that residue may have just blown around their working area, or spilled).  If they were experimenting with different additives for texture/colour, they may have just got lucky..  It certainly seems so, as if it was a deliberate technique we would find more, no?

 

As for it being beyond what we can do now, I would strongly dispute that.

Edited August 21, 2016 by ChrLzs

[Hod]

2 minutes ago, ChrLzs said:

Forgive me for being a devil's advocate here.. but if this was an example of something other than a happy accident, why aren't there lot's of other examples from that time/region?

By a happy accident, I mean that its existence could be explained by the accidental addition/contamination of the right amount of an impurity such as a metallic oxide powder.  This is *not* necessarily an example of some sort of nano-technology or precision grinding, but is much more likely to simply be a deposition of a powdery 'scale', possibly even from a simple chemical reaction/electrolysis or similar (and that residue may have just blown around their working area, or spilled).  If they were experimenting with different additives for texture/colour, they may have just got lucky..  It certainly seems so, as if it was a deliberate technique we would find more, no?

Definitely could have been happen-stance. But here is what the researcher said about that possibility:

Quote

The exact mixture of the precious metals suggests the Romans knew what they were doing—“an amazing feat,” says one of the researchers, archaeologist Ian Freestone of University College London.

 

3 minutes ago, ChrLzs said:

As for it being beyond what we can do now, I would strongly dispute that.

Not saying you're wrong, but do you have some links or any other evidence that supports your dispute?

[Hod]

11 minutes ago, ChrLzs said:

 If they were experimenting with different additives for texture/colour, they may have just got lucky..  It certainly seems so, as if it was a deliberate technique we would find more, no?

As to this, Wikipedia says:

Quote

It is the only complete Roman glass object made from this type of glass,^[2]

Which seems to imply that more glass like this has been found, but this is the only complete piece.

[Hod]

@ChrLzs No malcontent in my replies. Just as you're playing Devil's Advocate, I'm just playing Original Poster.

[ChrLzs]

1 minute ago, Hod said:

Definitely could have been happen-stance. But here is what the researcher said about that possibility:

Quote

The exact mixture of the precious metals suggests the Romans knew what they were doing—“an amazing feat,” says one of the researchers, archaeologist Ian Freestone of University College London.

 

Don't apologise, I am not offended by your tone (I'm usually the one that gets criticism for that!), but you did first say it could be happenstance, and then you go by the researcher who has not given any explanation of why it would be 'amazing'?  You need to consider just how much glassware has been created over the ages, and how many different impurities and additives and colorings were tried.  Probably some other examples were just tossed away as no-one checked the lighting from different angles.    Does that researcher name the actual particle mix, the sizes, and also the range of amounts that would cause the effect?  If not, his handwaving is even less useful than mine.. At least I'm thinking about it from all angles, not just the 'amazing' one....:D   Also bear in mind that once they noticed the effect, they could have remelted it down, and even tried diluting the formula to get the best effect.

1 minute ago, Hod said:

Not saying you're wrong, but do you have some links or any other evidence that supports your dispute?

I'd suggest you go to Google Images, and then search 'dichroic glass examples'.  The recent stuff makes that cup look a little colorless, and if you look carefully, you'll find a few (but very few) examples of old stuff in there...

[ChrLzs]

And here (there's a link to the PDF - it's a free download):

http://link.springer.com/article/10.1007/BF03215599

.. interested readers will find lots of technical discussion, and yeah, I reckon 'happy accident' sounds about right!  They used many techniques, including lots of different additives and additive methods plus subsequent tempering/heat-treatments, so who knows how many iterations they went thru, plus it would be virtually impossible given the number of variables, to match the result.

I'll quote the full conclusion:

Quote

Conclusion
The Lycurgus Cup demonstrates a short-lived technology developed in the fourth century A.D. by Roman glass-workers. They discovered that glass could be coloured red and unusual colour change effects generated by the addition of a precious metal bearing material when the glass was molten. We now understand that these effects are due to the development of nanoparticles in the glass. However, the inability to control the colourant process meant that relatively few glasses of this type were produced, and even fewer survive. The Cup is the outstanding example of this technology in every respect - its outstanding cut work and red-green dichroism render it a unique record.

 

[stereologist]

I was once told that the ability of the ancients to make tiny gold balls to place on objects as decorations was a lost art for many centuries. How it was done was reinvented by a mistake. Gold spilled onto charcoal bits splashes around and forms little balls. The gold is easy to separate from the charcoal. Little balls are saved and irregular pieces are melted and poured again. The rediscovery of this technique involved a mistake when gold was spilled.

Maybe this cup was formed by mistake. I know gold is used to make glass a deep red color. A nice discussion of the use of gold for ruby red glass is at the Corning site.

http://www.cmog.org/article/gold-ruby-glass

The wikipedia calls this glass cranberry glass. The link below refers to the cup.

https://en.wikipedia.org/wiki/Cranberry_glass

The wikipedia page on silver tells us that silver is mixed with glass to make a yellow or orange colored glass.

https://en.wikipedia.org/wiki/Silver