Augen

[1] Feldspar, quartz, and garnet are common minerals which form augen.

[2] Augen form in rocks which have undergone metamorphism and shearing.

The core of the augen is a porphyroblast or porphyroclast of a hard, resilient mineral such as garnet.

In this case, the position of the tails is unequal across the foliation, with some augen showing clear drag folding of the mantle into the strain shadow.

[1] A long wall of this augen gneiss can be felt at the Mineral and Lapidary Museum of Western North Carolina.