halyards turning black

[fbenkautz]

My halyards keep turning black on my 1977 23' S2.
I have replaced the blocks,but the black seems to be coming from up inside the mast. I have cleaned out the inside of the mast and it doesn't help.
Has anyone had this problem?

 

[Kordie]

Could it be mould?

 

[fbenkautz]

Dirty halyards

No, it is not mold, but a blackish gray like what would rub off the anodized metal, except we cleaned the inside of the mast.