Black Tourmaline Crystal bracelet

Tourmaline is a mineral that can be found in a variety of geological settings, including:

Tourmaline is commonly found in granite and pegmatites, especially in the form of visible crystals.

Tourmaline can be found in metamorphic rocks such as schist and marble. Magnesium-rich tourmalines, also known as dravites, are usually found in these rocks. 

Tourmaline can be found in minor amounts in sandstone and conglomerate as grains. It's also a common accessory mineral in sedimentary rocks because it's resistant to weathering. 

Tourmaline can be found in metasomatically altered limestone and dolomite in contact metamorphic zones. 

Tourmaline is a hard mineral with a glassy to pearly luster. It's commonly black, but can also be green, brown, red, blue, yellow, or pink. Tourmaline is known for its unique electrical properties, including pyroelectricity and piezoelectricity. Pyroelectricity is the ability to generate an electric charge when heated or cooled, while piezoelectricity is the ability to generate an electric charge under mechanical stress. 

Tourmaline is used in a variety of applications, including gemstones and in high-pressure gauges.