Spy Rock is a pink granite dome located in the Llano Uplift

Llano Uplift

The Llano Uplift is a roughly circular geologic dome of Precambrian rock, primarily granite, in Central Texas in the United States. It is located in the eastern region of the Edwards Plateau, west of the Texas Hill Country...

 in Mason County, Texas

Mason County, Texas

Mason County is a county located on the Edwards Plateau in the U.S. state of Texas. In 2010, its population was 4, 012. Its county seat is Mason...

, rising 1749 feet (533.1 m) feet above sea level. The peak is located south of Fredonia

Fredonia, Mason County, Texas

Fredonia is an unincorporated community in Mason County, Texas, United States. The community is located near the county line of Mason and San Saba counties, where State Highway 71 intersects with Farm to Market Road 386...

 on Farm to Market Road 386, west on Spy Rock Road.

As with Enchanted Rock

Enchanted Rock

Enchanted Rock is an enormous pink granite pluton rock formation located in the Llano Uplift approximately north of Fredericksburg, Texas, USA and south of Llano, Texas. Enchanted Rock State Natural Area, which includes Enchanted Rock and surrounding land, spans the border between Gillespie...

, Spy Rock is formed of middle Precambrian

Precambrian

The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...

material. The base of the peak can be reached by the public, but the dome itself is on private property.