It's a large formation, visible as you are hiking up from the wash. It is south of Throne of the Matriarch.
It's best to refer to a map in one of the guidebooks (e.g. page 341 in Randy Vogel's 1992 guide). Hike past Frontier Wall, follow the main wash north, then east, and finally back northwest. Then leave the wash and hike northeast to the rock.
1 Total Routes
['4 Stars',0],['3 Stars',1],['2 Stars',0],['1 Star',0],['Bomb',0]