McAfee SECURE sites help keep you safe from identity theft, credit card fraud, spyware, spam, viruses and online scams

Home » Minerals » Tourmaline

Tourmaline


Mineral Properties and Uses



Physical Properties of Tourmaline

Chemical Classification silicate
Color bluish black, black, yellow, pink, blue, green, colorless, red
Streak colorless, gray
Luster vitreous
Diaphaneity transparent to nearly opaque
Cleavage poor
Mohs Hardness 7 to 7.5
Specific Gravity 3 to 3.3
Diagnostic Properties lack of cleavage, color
Chemical Composition (Ca,K,Na,[])(Al,Fe,Li,Mg,Mn)3(Al,Cr, Fe,V)6
(BO3)3(Si,Al,B)6O18(OH,F)4
Crystal System hexagonal
Uses gemstone


Tourmaline beads
The variety in tourmaliine color is shown with this strand of beads.


Tourmaline cabs
Numerous cabochons of tourmaline from Africa. Each gem is approximately 6 millimeters by 4 millimeters.


Tourmaline gemstone
A cut piece of tourmaline. The gemstone is approximately 1.8 carats, and 9 millimeters by 7 millimeters.


Tourmaline teardrop cab
A teardrop cabochon of tourmaline from San Diego, California. The gemstone is approximately 1.4 carats, and 9 millimeters by 5 millimeters.



Find it on Geology.com




More from Geology.com


Methane Hydrate
Methane Hydrate deposits contain more fuel value than all other fossil fuels combined.
World Oil Shales
Oil Shales in Australia, Brazil, Canada, China, Israel, Russia, Syria, United States and others.
dowsing
Dowsing is a method used to find underground water that is rejected by most geologists.
shale gas
Shale Gas is natural gas trapped within shale. It is a growing source of US supply.
Crushed Stone
Crushed Stone - About four tons per person is used each year in the United States.
volcanic explosivity index
Volcanic Explosivity: Learn about some of the most explosive volcanic eruptions.
lightning map
Lightning Strikes Map - A NASA map showing the worldwide distribution of lightning activity.
Largest Desert
Largest Desert: The Sahara is huge but two polar deserts are larger.


Tourmaline crystals
Colorful gem-quality tourmaline crystals from Brazil showing the typical prismatic habit with striations. Image © iStockphoto and MarcelC.




Tourmaline in granite
Tourmaline in granite from Stoneham, Maine. Specimen is approximately 5 inches (12.7 centimeters) across.


Tourmaline
A close-up of tourmaline from Pierrepont, New York. The overall specimen is approximately 4 inches (10 centimeters) across.


Tourmaline from NY
Tourmaline from Pierrepont, New York. Specimen is approximately 3 inches (7.6 centimeters) across.


Tourmaline in microcline
Tourmaline in microcline from Bathurst, Ontario, Canada. Specimen is approximately 3 inches (7.6 centimeters) across.


More Minerals
  Minerals
  Quartz
  Mineral Identification Chart
  Fluorescent Minerals
  Find Minerals and Gems
  Diamond
  Calcite
  Corundum




© 2005-2015 Geology.com. All Rights Reserved.
Images, code and content of this website are property of Geology.com. Use without permission is prohibited. Pages on this site are protected by Copyscape.