DRAVITE (Tourmaline)
Dravite Tourmaline: Brown Color, Properties & Formation
Dravite is a member of the tourmaline mineral group, generally described as a sodium- and magnesium-rich tourmaline. It commonly appears brown, yellow-brown, or dark brown, though its color varies with chemistry. It is collected as a mineral and may occasionally be cut as a gemstone.
Table of Contents
Quick Facts
- Mineral group: tourmaline.
- Ideal end-member composition: sodium magnesium borosilicate.
- Common colors: brown, yellow-brown, and dark brown.
- Tourmaline crystals often have striated prismatic faces.
Dravite Composition and Tourmaline Group
Tourmaline is a complex borosilicate group with many chemical substitutions. Dravite is the magnesium-rich end member of the alkali tourmalines, while schorl is richer in iron. Natural crystals can have compositions between ideal end members, so color alone cannot establish species.
Dravite Geological Formation
Dravite occurs in metamorphic and boron-rich environments, sometimes associated with marble, dolomite, serpentinite, and other magnesium-rich rocks. Boron-bearing fluids and available magnesium help determine where it forms. Matrix and locality information can clarify a specimen’s geological context.
Dravite Color and Crystal Habit
Dravite is often brown to yellow-brown, though other tones can occur. Tourmalines commonly form elongated, striated prismatic crystals and may show triangular cross-sections. Brown tourmaline is not automatically dravite; iron-rich schorl and mixed compositions can look similar.
Dravite Collecting and Uses
Dravite is collected for its tourmaline crystal form, color, and geological associations. Transparent material may be faceted, but appearance and market interest vary. Use the best-supported mineral name on labels and retain locality or analytical records.
Dravite Care and Cleaning
Tourmaline has Mohs hardness around 7–7.5, but crystals can chip or fracture. Use mild soap, lukewarm water, and a soft brush when appropriate. Protect crystal points, avoid sudden temperature changes, and consult a gem professional before ultrasonic cleaning if fractures or treatments are uncertain.
Frequently Asked Questions
Is every brown tourmaline dravite?
No. Other tourmaline compositions may be brown too; chemical evidence is needed when precise species identification matters.
Can dravite be faceted?
Some transparent material can be cut, though dravite is chiefly of interest to mineral collectors.
Further Reading & Sources
- Mindat — mineral data and localities.
- Handbook of Mineralogy — technical descriptions.
- Gemological Institute of America — gem education.
- Wikipedia: Dravite — background and references.