Gneiss is a metamorphic rock, meaning it forms from existing rocks that are changed by heat and pressure. You won't find it in a specific location, but rather in areas where these metamorphic conditions exist. Here's where gneiss commonly occurs:

* Mountain Ranges: Gneiss is often found in the core of mountain ranges, formed by the intense pressure and heat associated with mountain building (orogeny).

* Shields: Ancient, stable portions of the Earth's crust called shields are also common locations for gneiss. These areas have been subjected to intense heat and pressure over billions of years.

* Metamorphic Belts: Zones of metamorphic rocks, often adjacent to mountain ranges, are rich in gneiss.

Examples of regions with extensive gneiss formations:

* Canadian Shield: This ancient geological formation in North America is known for its vast expanse of gneiss.

* The Alps: The core of the European Alps is composed of a variety of metamorphic rocks, including gneiss.

* The Himalayas: The towering Himalayan range contains a significant amount of gneiss, formed by the collision of tectonic plates.

Remember: Gneiss can be found in other places as well, depending on the geological history of the region.