Gneiss

Gneiss (pronounced nice), a very common metamorphic rock made up mostly of quartz and feldspar, can also contain some mica. Gneiss is commonly crudely banded with layers defined by light and dark minerals. Gneiss can develop from granite or a clastic sedimentary rock (rock composed of broken fragments from preexisting rock, commonly sandstone). Gneiss in Texas is exclusively Precambrian in age. It can be used as aggregate or building stone.

The gneiss sample in the Texas Rock Kit was collected in the Llano Uplift.