Gneiss

Hardness of 6-7 on Mohs scale, characterized by distinct alternating light and dark compositional banding. Displays a foliated structure with medium to coarse-grained texture and a vitreous to sub-resinous luster.

Formed through high-grade regional metamorphism of pre-existing igneous or sedimentary rocks under extreme heat and pressure, typically occurring deep within the Earth's crust during mountain-building events.

Used primarily in the construction industry as crushed stone for roadbeds, building foundations, and dimension stone for facing buildings.

Gneiss can contain some of the oldest rocks found on Earth, dating back over 4 billion years. The distinct light and dark bands are known as gneissic banding, created by the segregation of minerals like quartz, feldspar, and biotite.

Easily identifiable in the field by its striking zebra-like banded pattern of light and dark minerals. Commonly found in ancient continental shields and eroded mountain belts worldwide.