Identification guide · Minerals
How to Identify Tourmaline
Tourmaline forms elongated, striated prismatic crystals with a distinctive rounded-triangular cross-section, in colors ranging from black and brown to vivid pink, green, and blue, sometimes zoned within a single crystal. Luster is vitreous, streak is white or colorless, and hardness is 7 to 7.5. It has no true cleavage, breaking instead with a conchoidal to uneven fracture. Its triangular cross-section and color zoning usually separate it from beryl and quartz, which lack both features.
Tourmaline identification checklist
| Color | Black, Green, Pink, Blue, Multicolored (watermelon) | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Transparent to opaque | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 7–7.5 | It scratches glass and a steel knife and cannot be scratched by a steel file. |
| Streak | White (colorless) | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | None (indistinct) | |
| Fracture | Conchoidal to uneven | Broken surfaces show smooth, curved, shell-like scoops. |
| Specific gravity | 3.0–3.25 | Heavier than it looks (specific gravity about 3.125). |
| Crystal system | Trigonal |
Extra tests for Tourmaline
Glass check. Tourmaline shares a glassy luster and conchoidal fracture with man-made glass. Glass sits near Mohs 5.5 and often contains round gas bubbles, so a hardness test and a hand lens separate them.
Tourmaline look-alikes and how to tell them apart
Both sit near Mohs 7–7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Tourmaline vs Elbaite →
Tourmaline is harder (Mohs 7–7.5) than Calcite (Mohs 3), so Tourmaline will scratch Calcite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Tourmaline vs Calcite →
Both sit near Mohs 7–7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Tourmaline vs Beryl →
Tourmaline is harder (Mohs 7–7.5) than Diopside (Mohs 5.5–6.5), so Tourmaline will scratch Diopside and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
Tourmaline identification FAQ
How can you tell if a rock is Tourmaline?
Check the color (black, green, pink, and blue), the vitreous luster, a Mohs hardness of 7–7.5 and a white (colorless) streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Tourmaline?
Tourmaline has a Mohs hardness of 7–7.5. It scratches glass and a steel knife and cannot be scratched by a steel file.
What is the difference between Tourmaline and Elbaite?
Tourmaline (Mohs 7–7.5, vitreous luster) and Elbaite (Mohs 7–7.5, vitreous luster) look alike, but hardness, streak and heft usually separate them. See the full Tourmaline vs Elbaite comparison for a side-by-side table.
Is Tourmaline worth anything?
Entry-level Tourmaline specimens sell for around $2, typical collector pieces about $20, and premium examples $150 or more depending on size, quality and locality.
What color is Tourmaline?
Tourmaline is most often black, green, pink, and blue. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
