Black rock Loop is located in Tucson Mountain Park in an area they call Sweetwater Preserve. This area has many trails to combine together for some longer hikes.
Black Rock loop is made up of Saguaro Vista, Sunset Circle and Black Rock trails. it is a 4 mile loop and is rated as an easy hike (Hiking Difficulty Calculator) The trail surface varies from rocky to hard packed earth.
Be sure to be on the lookout for the Crested Saguaro!