I don’t think I’ve ever seen anything like this around a chimney. Is this some type of blanket/cover protector? The brick in the attic for the chimney looked really old. The house was built in 1925.
Looks like someone is trying to hide the fact the chimney is failing!! Write it up HARD for a minimum “Level II” Chimney Inspection/Certification Evaluation from a Certified Chimney Inspector!!
Yes, JJ’s got it. It looks like someone large coated the exterior of the chimney and painted it black. Except there appear to be holes into the attic via the missing mortar, and probably down through the walls, where CO can come out and potentially kill the sleeping people.