This tube was made around the 1930s and contains a pigment very common during the 19th century. It is classed as poisonous and so if used great care must be taken. 
That said it is a beautiful green and was a great favourite of such esteemed masters as Vincent Van Gogh amongst others. 
It is a genuinely rare paint and will never be made again. 
 
This paint is normally very expensive but because this is a part used tube I have priced it accordingly. 
 
This was made by Winsor and Newton and these old paints by these makers in metal tubes carry a large pigment load as do Roberson and Reeves. 
 
I keep a good stock of this for my own work as a Museum’s conservator and for my art works. 
 
The real benefit of these old paints is that they have stood the test of time. 
They cover very many canvases in innumerable galleries.