Caw's ink, NY

[JForshey]

I'm helping with an estate and came across this little bottle. I'm curious if anyone can give me info, especially approximate age and value? I don't want to toss something of value, but there is a lot of stuff and I only collect Mason jars! It seems to have an iridescent paint or glaze on the outside.

 

[Skoda]

That iridescence was caused from it being buried in the ground for 100+ years- to quote an article on ancientglass.wordpress:

Natural iridescence is sometimes found on modern glass bottles from digs in the back yards of old houses or pulled out of river beds. The word iridescence comes from Iris, the Greek Goddess of rainbows and refers to rainbow-like colors seen on the glass which changes in different lighting. It is simply caused by alkali (soluble salt) being leached from the glass by slightly acidic water and then forming fine layers that eventually separate slightly or flake off causing a prism effect on light bouncing off and passing through the surface which reflects light differently, resulting in an iridescent appearance.

Those inks are seemingly pretty common and would likely only fetch between $5-10. The "sick glass" iridescence does make it very visually appealing, though!