Purple Tourmaline Identification Guide
Identify purple tourmaline (violet elbaite) by its striated triangular prisms, hardness 7–7.5, pleochroism, and lack of cleavage.
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What Purple Tourmaline Looks Like
Purple Tourmaline is a violet to purple variety of elbaite (sometimes called siberite for deep violet stones), colored by manganese. Like all tourmaline it is trigonal, forming elongated prismatic crystals with a rounded triangular cross-section and strong vertical striations along the prism. It is transparent to translucent with a vitreous luster and exhibits clear pleochroism, often shifting between purple and a paler or bluish tone.
Step-by-Step Field ID Checklist
- Crystal shape: Look for a long prism with a rounded triangular cross-section.
- Striations: Confirm lengthwise grooves on the prism faces.
- Hardness test: It scratches glass easily (Mohs 7–7.5).
- Pleochroism: Rotate in light to watch the violet color shift.
- Cleavage check: No cleavage; fracture is uneven to conchoidal.
Key Diagnostic Tests
- Mohs hardness: 7–7.5.
- Streak: white.
- Cleavage: none — important versus cleavable purple minerals.
- Specific gravity: ~3.0–3.1.
- Pyro/piezoelectricity: develops static charge when heated or stressed, attracting dust.
Common Look-Alikes and How to Tell Them Apart
- Amethyst: quartz with hexagonal crystals and horizontal striations; tourmaline shows a triangular section with vertical striations.
- Iolite (cordierite): strongly pleochroic but orthorhombic with cleavage and a different habit; tourmaline lacks cleavage.
- Purple sapphire: much harder (Mohs 9) and forms hexagonal/barrel crystals.
- Sugilite / charoite: opaque, massive, or fibrous purples without the clear striated triangular prism.
The decisive features are the rounded triangular cross-section, vertical striations, hardness 7–7.5, strong pleochroism, and no cleavage.
Where It Is Found
Purple/violet elbaite forms in granite pegmatites. Significant sources include Brazil, Madagascar, Afghanistan and Pakistan, Nigeria, and the USA (Maine and California pegmatites).
Frequently asked questions
How can you tell if it's real purple tourmaline?
Look for a striated crystal with a rounded triangular cross-section, a hardness of 7–7.5, strong pleochroism, and no cleavage — these together confirm tourmaline.
Purple tourmaline vs amethyst — how do they differ?
Amethyst is hexagonal quartz with horizontal striations, while purple tourmaline has a triangular cross-section with vertical striations and stronger pleochroism, though both have similar hardness.
What does purple tourmaline look like?
It is a transparent-to-translucent violet crystal, typically an elongated striated prism with a rounded triangular cross-section that shifts color when rotated.
Is purple tourmaline the same as siberite?
Siberite is a name used for deep violet-purple elbaite tourmaline, so it falls within the purple tourmaline category, colored by manganese.