silicates
Tourmaline
- Also known as
- elbaiteschorlrubelliteindicolitewatermelon tourmaline
- Crystal system
- trigonal
- Hardness
- 7–7.5 on the Mohs scale
- Lustre
- vitreous
- Colour
- Every colour, frequently several in one crystal
- Where it forms
- In granite pegmatites and in some metamorphic rocks. Tourmaline is a boron mineral, and boron concentrates in the last fluids to crystallise.
- Chiefly from
- Minas Gerais, BrazilParaiba, BrazilAfghanistanMozambiqueCalifornia, United States
Why it is that colour
Different metals in different structural sites — iron for black, lithium and manganese for pink, copper for the neon blues of Paraiba material, chromium and vanadium for green. The chemistry can change as the crystal grows, which is why single crystals are often zoned along their length.
Safety
Safe to handle. Tourmaline is sold in hair straighteners and heating devices on the claim that it emits negative ions and far-infrared radiation; it is pyroelectric and piezoelectric, so it does develop a surface charge when heated, but the effect is minute and nothing about a ceramic coating containing tourmaline powder does anything to hair.
Where it comes from
Brazilian and African material dominates. Afghan and Pakistani mining is small-scale and hazardous. Paraiba tourmaline from the original Brazilian deposit is among the most expensive gems by weight of anything on earth, and copper-bearing material from Mozambique and Nigeria is sold under the same name, which is contested.
Historical use
Genuinely pyroelectric: heat a tourmaline crystal and opposite ends develop opposite electrical charges. This was the first pyroelectric effect studied scientifically, and tourmaline was the material in which the Curie brothers investigated piezoelectricity before turning to quartz.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
What is attributed to it, and since when
Tourmaline reached Europe in quantity only in 1703, brought from Sri Lanka by Dutch traders, so it has no classical or medieval tradition. Dutch merchants noticed that heated crystals attracted ash and called them aschentrekker. Its modern meanings, and the specifically strong reputation of black tourmaline for protection, are New Age.
Described, not endorsed. Dating a claim is not the same as assessing it — but an association that first appears in a book published in 1985 is not an ancient inheritance, whatever the label says. A sincere account of feeling better is compatible with the stone doing nothing — see the placebo effect.
Worth knowing
Tourmaline is a group of more than thirty species, and its structure is remarkably accommodating — it will take almost any metal into one site or another, which is why it comes in more colours than any other mineral. Crystals commonly change colour along their length as the chemistry of the fluid around them changed, so a single tourmaline can be black at one end and pink at the other.
The pyroelectric property is genuine and historically important. Heated tourmaline develops a charge, and eighteenth-century Dutch traders used the crystals to pull ash out of their pipes. That is a real physical effect, it was studied seriously by the Curies, and it does not scale to anything a hair straightener could use — the charge is tiny and it decays.
Identity checked against IMA-CNMNC master list, June 2025.