What is it and where is it formed?   Gneiss is a rock that has streaks of minerals through it.  Most of the time, it has feldspar, quartz, and mica in it.  It is named for the mineral that’s in it the most.  An example of this is garnet gneiss which has mostly garnet in it.  It doesn’t mean that is the only mineral in it—just the highest amount.  It is formed in igneous, but most often metamorphic rocks.  Gneiss is formed when there is a lot of pressure and heat and the rocks melt. 

How and where is it mined?  Gneiss are mined using underground mining.  It is found all over the world but mostly in mountain ranges like the Adirondacks and the Rocky Mountains.

What is it used for?  Gneiss is used in buildings, roads, and curbs.