Black Tourmaline
Scientific Name: Schrol
Chemical Formula: NaFe2+3Al6(BO3)3Si6O18(OH)4
Composition: Basic sodium iron aluminum boro-silicate
Color: Black
Mohs Hardness: 7 – 7.5
Crystal System: Hexagonal
Rock Type: Igneous, Metamorphic
Lustre: Vitreous, Resinous
Black Tourmaline is part of the Tourmaline of which there are a few variations. The actual scientific name for Black Tourmaline is Schorl.
Schorl most commonly contains the elements of sodium, iron, aluminium, magnesium, lithium or potassium.
Types or Varieties of Tourmaline:
Schorl: Colored Brown to Black
Dravite: Colored dark yellow to brownish black
Elbaite: Comes in four Variations including Rubellite, Indicolite, Verdelite and Achroite
Rubellite: Colored Red to Pink
Indicolite: Colored Blue/Green to Light Blue
Verdelite: Green
Achroite: Colorless
Other Occurrences
Schorl (Black Tourmaline) can sometimes form as needles within clear Quartz. When this occurs it forms the crystal called Tourmalated Quartz.