Old coin which fluoresces under short wave UV.

[FrumiousBandersnatch]

I took images of a 1947 Australian Florin coin under fluorescent, short wave and long wave UV lighting.
What I find puzzling is why the coin should fluoresce in the first place.

The coin has a composition of 50% silver, 40% copper, 5% nickel, 5% zinc.
The coin probably has a tarnish but why this should fluoresce at 254 nm is a mystery to me.
The blue specks in the 365 nm image are due to microfiber contamination.
Any suggestions to what is going on?
No other coins I have imaged exhibit fluorescence.

Googling does suggest that silver oxide and silver nanoparticles will fluorescence under UV in certain conditions. I couldn't say why.

 

[SelfSim]

Was musing that some residual cleaning compound might responsible .. eg: Brasso.
However, it doesn't seem to contain anything I can find which would produce green fluorescence, specifically under 254nm UV.

The mineral adamite seems a good candidate but there doesn't seem to be any good reason for it being present on a coin(?)

Perhaps the coin was used at some rave party where people were using some UV flourescent makeup .. or maybe even it was @sjastro's pre-rave makeup which contaminated the sample(?)

 

[sjastro]

Some more interesting info.
I did a comparison between a 1952 Australian and a 1937 New Zealand Shilling.

There is something odd about Australian coins under shortwave UV.

What's even more mysterious is a 2000 year old Roman denarius produced in the reign of the emperor Trajan.
At this time the denarius was 90% silver and 10% copper.
Handling the coin with gloves I took images under fluorescent light of both sides and shortwave/longwave UV of the Concordia side.

The reddish image in the longwave image is not due to fluorescence but reflected UV recorded by the camera since the UV coating on the lens was not able to absorb all the longwave UV.

​

 

[sjastro]

Perhaps the coin was used at some rave party where people were using some UV flourescent makeup .. or maybe even it was @sjastro's pre-rave makeup which contaminated the sample(?)

My secret is out.
The easiest method of determining whether an organic coating is involved is to clean the coin (not the denarius which is untouchable) with acetone and do a comparison shortwave UV image.

 

[essentialsaltes]

Some more interesting info.

There is something odd about Australian coins under shortwave UV.

That is odd. I can only assume that like everything else in Australia, it's trying to kill you, and this is how you can tell it's as venomous as a platypus spur.

What's even more mysterious is a 2000 year old Roman denarius produced in the reign of the emperor Trajan.

I think that looks a bit more like Hadrian's profile, Trajan's cousin and successor. The CAESAR TRAIAN is in a similar spot as yours, but the legend runs off the edge. I suspect it would be followed by HADRIANVS.

 

[sjastro]

That is odd. I can only assume that like everything else in Australia, it's trying to kill you, and this is how you can tell it's as venomous as a platypus spur.

Or the second deadliest land snake the Eastern Brown.
I live in rural Australia and these critters reside under the concrete slab and come out to warm up on the veranda.
I need to be very careful when entering or existing the house...........

​

I think that looks a bit more like Hadrian's profile, Trajan's cousin and successor. The CAESAR TRAIAN is in a similar spot as yours, but the legend runs off the edge. I suspect it would be followed by HADRIANVS.

According to the Certificate of Authenticity it's Trajan.
On the certificate the full detail of Trajan's name is revealed.

 

[SelfSim]

There is something odd about Australian coins under shortwave UV.

So, Wiki says that particular Aus shilling's composition should be:

50.0‰ silver, 40‰ copper, 5‰ nickel, 5‰ zinc

.. and I don't think many made their way through the Christmas pudding cooking process either .. (Threepences were a different story though ..)

 

[SelfSim]

According to the Certificate of Authenticity it's Trajan.
On the certificate the full detail of Trajan's name is revealed.

Its fraud .. or just fake news!

 

[sjastro]

I cleaned the 1947 Florin with Windex and did a before and after comparison under shortwave UV.

During cleaning I used white paper towelling which remained white.
This indicates there was no transference of silver oxide which is black in colour and effectively eliminates silver oxide or tarnish as the cause.
I’m not convinced fluorescence is due to some organic residue.
It doesn’t explain why there is no fluorescence under longwave UV.

To complicate matters I used a solvent based lacquer for providing a protective film on ceramic tiles and got an opposite result when applied to a 20 cent piece; it fluoresces under longwave UV and not shortwave UV!!

This mysterious substance will remain mysterious unless an FTIR is used to determine if the coin has an organic film or XRF is used for elemental analysis.

 

[sjastro]

As an off topic human interest story for those that have an obsessive compulsive disorder with cleanliness do not purchase, I repeat do not purchase a longwave UV torch.
Even a reasonably looking clean wall under ordinary lighting conditions is going to be a nightmare scenario under longwave UV.

 

[FrumiousBandersnatch]

As an off topic human interest story for those that have an obsessive compulsive disorder with cleanliness do not purchase, I repeat do not purchase a longwave UV torch.
Even a reasonably looking clean wall under ordinary lighting conditions is going to be a nightmare scenario under longwave UV.

Just think of it as, 'the more UV reflected, the cleaner the surface'

 

[SelfSim]

As an off topic human interest story for those that have an obsessive compulsive disorder with cleanliness do not purchase, I repeat do not purchase a longwave UV torch.
Even a reasonably looking clean wall under ordinary lighting conditions is going to be a nightmare scenario under longwave UV.

I'd hate to see what my skin looks like under UV then ..

 

[Occams Barber]

Or the second deadliest land snake the Eastern Brown.
I live in rural Australia and these critters reside under the concrete slab and come out to warm up on the veranda.
I need to be very careful when entering or existing the house...........

​

I know the feeling.

I live in a small, coastal rural village. My place backs on to the ocean foreshore which is known locally as Snake Alley - mainly Brown Snakes and an assortment of back fanged and constrictor type wrigglies.

A couple of months back I had 2 metres of Carpet Python take up residence on my upstairs window ledge. It stayed for a week.

Last week my neighbour found a smallish brown coloured snake on her back porch. We think it was a Yellow Faced Whip Snake (back fanged, mildly poisonous, but not deadly).

Snake skins are so common here the kids don't even bother taking them to school for 'Show & Tell'.

Remind me to buy some shoes.

OB

 

[SelfSim]

Remind me to buy some shoes.

Gumboots?
(Mind you, I've never tested them to see if a fang can penetrate the rubber ..)

 

[sjastro]

Gumboots?
(Mind you, I've never tested them to see if a fang can penetrate the rubber ..)

I purchased a pair of "snake proof" boots from the US a few years ago only to find they are not terribly useful as protection against the Eastern Brown.
The boots extend to just below the knee while the vast majority of Eastern Brown bites occur to the thigh region as the snake strikes from a high vertical position.

The saving grace for me in my frequent unintentional encounters with the Eastern Brown over the years is that they don't appear to be aggressive.
On one occasion I was slashing the grass around the property when I noticed a tail sticking out of the long grass. I thought it the tail of a blue tongue lizard.
I gave it a tap with my boot as I didn't want to injure or kill it; the tail turned out to being an Eastern Brown which then wrapped itself around my boot.
It took a few seconds to extract the snake in a kicking action but once it was air borne it probably would have made it in the Guinness Book of Records for the longest flight taken by a snake.
I suspect the snake was more in a state of shock than I was.

 

[Bungle_Bear]

I purchased a pair of "snake proof" boots from the US a few years ago only to find they are not terribly useful as protection against the Eastern Brown.
The boots extend to just below the knee while the vast majority of Eastern Brown bites occur to the thigh region as the snake strikes from a high vertical position.

The saving grace for me in my frequent unintentional encounters with the Eastern Brown over the years is that they don't appear to be aggressive.
On one occasion I was slashing the grass around the property when I noticed a tail sticking out of the long grass. I thought it the tail of a blue tongue lizard.
I gave it a tap with my boot as I didn't want to injure or kill it; the tail turned out to being an Eastern Brown which then wrapped itself around my boot.
It took a few seconds to extract the snake in a kicking action but once it was air borne it probably would have made it in the Guinness Book of Records for the longest flight taken by a snake.
I suspect the snake was more in a state of shock than I was.

If I may slightly misquote Neville Flynn from Snakes on a Plane: "I have had it with this <expletive deleted> snake on my <expletive deleted> boot!"

 

[Occams Barber]

I purchased a pair of "snake proof" boots from the US a few years ago only to find they are not terribly useful as protection against the Eastern Brown.
The boots extend to just below the knee while the vast majority of Eastern Brown bites occur to the thigh region as the snake strikes from a high vertical position.

The saving grace for me in my frequent unintentional encounters with the Eastern Brown over the years is that they don't appear to be aggressive.
On one occasion I was slashing the grass around the property when I noticed a tail sticking out of the long grass. I thought it the tail of a blue tongue lizard.
I gave it a tap with my boot as I didn't want to injure or kill it; the tail turned out to being an Eastern Brown which then wrapped itself around my boot.
It took a few seconds to extract the snake in a kicking action but once it was air borne it probably would have made it in the Guinness Book of Records for the longest flight taken by a snake.
I suspect the snake was more in a state of shock than I was.

This broke me up. It reminded me of the times I've come close to crapping myself after almost standing on a snake or a big goanna or a bull ant nest - usually with no shoes on.

OB

 

[sjastro]

This broke me up. It reminded me of the times I've come close to crapping myself after almost standing on a snake or a big goanna or a bull ant nest - usually with no shoes on.

OB

No shoes on?
You must must have a death wish.

I found this video of a snake catcher handing an Eastern Brown like a strand of spaghetti, it made me cringe.

 

[SelfSim]

No shoes on?
You must must have a death wish.

I found this video of a snake catcher handing an Eastern Brown like a strand of spaghetti, it made me cringe.

Its interesting that when the snake has a go at him, what you say is right .. the snake is heading for his thigh just above the knee. (I did a frame-by-frame on the YouTube). I might have to rethink my defence strategy there ..

Compared with a black snake, I think they may be quicker and maybe that's why they're commonly said as being more aggressive(?)
(That's not to say your experiences of them not being too aggresive is just a fluke observation either - I guess how warmed up they might be, or how close to breeding season comes into the calculation too?).

I once saw a so-called bull shark expert doing a documentary and telling everyone how they'd leave you alone (if you made use of his so-called 'expert' knowledge).. so he was standing in thigh deep water with about 3 of them circling him to prove his point. All of a sudden, ene of 'em decided to have bite at his calf and ended up completely removing it. The dude ended up disabled for life as a result of that! (What an idiot!)

 

[sjastro]

Silver can now be 100% ruled out as a 1973 10 Drachmai coin exhibits fluorescence under shortwave UV.
This coin has a composition of copper 25% and nickel 75%.

Here is a microscopic image.

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The common denominator with this Greek coin, the Roman coin and the Australian Florin is copper.