This is characterized by light gray crenulated cleavage surfaces sprinkled with small garnet, biotite, and staurolite crystals.

The upper member is 5–10 meters (16–33 feet) of phyllitic slate that resembles the Pilar Formation but is distinguished by its stratigraphic position.

[3] Detrital zircon geochronology yields a maximum age of 1475 Mya, similar to the underlying Pilar Formation but considerably younger than the lower Hondo Group.

[4] The unit was originally mapped as part of the Rinconada Schist Member of the Ortega Formation by Arthur Montgomery in 1958.,[5] which it resembles except for having less abundant garnet.

[1] Nielsen recognized in 1972 that the beds were distinct from the upper Rinconada Schist[6] but erroneously assigned them to the Pilar Formation.