Mir-1 lens - yellow hue

I see this already in single transmission. Placing the lens on a white surface and looking through the front to that surface of course strengthens this effect.

The lens is not stated to be radioactive, nor could I meter such, though so far I only partially disassembled it.

Is this normal for this lens?

I have this lens and while I do not see much of a hue indoors I do recall seeing a bit of a yellowish orange tint on the glass which I always believed was the coating. AFAIK they are just regular coated glass.

My thought was that there is some high-refractive non-Thorium glass used in one of the elements and that it got that cast as such.