Featured Jasper ? Brooch

Jasper is a wild guess- what do you think please?
Definitely stone as cold. Slightly ordinary looking brown stone although it does fluoresce under UV on the lighter areas around the edge.
Mount is silver- haven’t found a hallmark yet!. Long pin and c clasp - early 20th c?
Thanks

 

If it was round, and the right size, I might suggest operculum, similar to this ring:

 

Could be Florida fossil walrus tusk,just a guess and it doesn't look like jasper.

 

The Victorians liked bulls eye agates set as jewellery, as well as other stones they found pretty or unusual. They also liked fossils & I agree that is what this appears to be, although I am not sure fossil what. I was thinking maybe a slice of crinoid stem, but not a good match.

Here are an agate & a slice of fossil coral:

 

What does it look like if you put your light behind?

Thinking Blue John :
https://bluejohnstone.com/product-category/blue-john-specimens/

 

Looking at some of the older specimens I suspect you could be right and that it's Blue John as it has similar characteristics. Would also explain why the victorians put a boring brown pebble in a silver mount!

 

Just for @kyratango

 

Now not so sure as there's no purple with a light shining through......

 

It's smooth, but not glossy. What does it feel like against the teeth? There's just something about the way the shades of brown are arranged that suggests a biologic rather than a geologic process at work. In some ways it looks like a type of shell that was occasionally used for cameos, just not quite.

 

It's cold like stone and chinks against my teeth like stone. TBH there are a lot of brown pebbles around Gloucestershire that look very similar but sense tells me you wouldn't go to the effort of putting one of those in a silver mount!.
Doesn't feel like shell as heavy too but could be a fossilised something!.

 

Ok, but is it translucent with the light behind?

 

Yes apart from the very centre.

 

Blue John can be brown
From here:
https://www.avantijewellers.co.uk/about-derbyshire-blue-john-i56
"Blue John is renowned for its banding stripes but it can vary greatly from very dark blues, to purples to yellow, white and even brown. Blue john is a crystallised formation and therefore sometimes marks can also be seen on the surface of the stone"

What leads me towards it is:
The cristalline texture of the lightest bands on the outer parts.(BJ is a crystalised feldspar) I did some work on your pics to enlight these:


The slight fluorescence under black light.(BJ is fluorite)
The scuffed surfaces. (BJ is 4 on the Mohs scale)
The Victorian era, British location of KSW (if I remember well).

@KSW, could you try a scratch test on back,
using either a glass shard or a knife blade as this useful list says:

Impatient to see your update

 

Sorry, I’m just nipping out!. I’ll do it as soon as I get home but your enhanced photo definitely has a purple hue to the centre. Thanks for your interest
P.s yes I’m in the UK

 

Nice!!! Thanks
The purple hue on my modified pics isn't strongly reliable... a pale whitish jadeite stone can show emerald green when the eye can't see it!
Jade buyers on internet... BEWARE!
I worked your pics to diminish the orange and show the bands better:

 

An interesting puzzle for us, K.
Blue John, although it is a form of fluorite, doesn't always fluoresce. It seems a lot of it doesn't. (I just wish stones would be consistent )

Here is some info on how to recognize stones from different veins:
http://www.bluejohnstone.co.uk/blue-john-veins.htm

 

Ok, so using my very *professional* Mohs testing I can tell you that
- a fingernail or wooden toothpick- no mark at all.
- the corner of a copper plate (see previous thread about photographic plates) made a small copper coloured mark but didn’t really go below the surface.
- stainless steel skewer made a proper scratch.
Does that help?

 

Testing is testing, if you don't have pro equipment, the usual objects in the list above give a good clue for the hardness of your stone

Your test situe it between 3 and 6.5 on Mohs scale which is consistent with the 4 range of BJ
Jasper is in the 6.5 / 7 range, and would not be scratched by your skewer!
Another useful list of jewellery stones classified by their Mohs scale range:

https://www.gemsociety.org/article/select-gems-ordered-mohs-hardness/