Mount TV in stone facade or drill through to chimney block?
So I took the better-safe-than-sorry approach, used a combination of 12" wood and masonry bits to drill through the facade, plywood backing, and into the blocks of the chimney. I used 3 masonry anchors in the chimney blocks, because I couldn't get a 4th one through the stone where it needed to be. The 3 anchor points are drilled through the mortar. The TV has been hanging for well over a year now, and hasn't fallen yet!