Black tourmaline, or schorl
Black tourmaline is crystal practice's stone of protection, often sold to “block EMF”. Here is what the mineral is, what it can and cannot do, and how to spot imitations.
The short answer
Black tourmaline, the mineral schorl, is a complex boron silicate, hardness 7 to 7.5, that grows as long, striated, black crystals. Crystal practice calls it the leading stone of protection. It is often sold as blocking electromagnetic fields (EMF) from phones and Wi-Fi; there is no evidence it does, and placing a stone near a device does not reduce its emissions. It is brittle along its length. Black glass, onyx and obsidian are sometimes sold as tourmaline.
In this guide
What black tourmaline is
Tourmaline is a family of boron silicate minerals, and schorl, the iron-rich black member, is the most common. Its crystals are long prisms with deep lengthwise grooves (striations) and a rounded triangular cross-section. Tourmaline is piezoelectric and pyroelectric: squeezing or warming it creates a small electric charge, which led Dutch traders to call it the “ash puller” because a warmed crystal attracted ash. Schorl is mined in Brazil, Africa, Pakistan and elsewhere, including in Indian pegmatites.
| Mineral | Schorl (iron-rich tourmaline) |
|---|---|
| Hardness | 7 to 7.5, brittle across its length |
| Main sources | Brazil, Africa, Pakistan, India |
| Water | Safe to rinse |
| Sunlight | Stable |
| Look | Black, striated prisms with a triangular cross-section |
Black tourmaline in crystal practice
Crystal practice calls black tourmaline the stone of protection and grounding: placed by the front door, carried, or worn to absorb “negative energy”. It is widely sold to shield people from the electromagnetic fields of phones, computers and Wi-Fi.
Black tourmaline absorbs negativity, grounds and protects, and shields against electromagnetic radiation from devices.
No controlled study has found that a crystal has effects beyond expectation. In a 2001 study at Goldsmiths, University of London, people holding fake crystals reported the same tingling, warmth and calm as people holding real quartz. A stone can still be a meaningful reminder, a ritual object or simply something beautiful to wear.
Real, treated or imitation?
Schorl is cheap and plentiful, so it is rarely treated. The risk is other black materials sold under its name.
| What you might be sold | What it is | How to tell |
|---|---|---|
| Black glass | Moulded glass | Smooth, no striations; bubbles; conchoidal (shell-like) breaks |
| Black onyx | Usually dyed chalcedony | Uniform, glossy black with no striations |
| Obsidian | Natural volcanic glass | Glassy, smooth, sharp curved breaks |
For more, see our guide to spotting dyed and fake crystals.
Wearing and care
Schorl is fairly hard but brittle and can snap across a long crystal if dropped. Rinse and dry it; it is stable in light and water.
Our care chart shows which crystals can go in water, salt and sunlight.
Buying black tourmaline
Readers often ask where to buy. We independently consider GemKrishna, an Indian retailer, a good source: its custom crystal bracelets come with a free GJSPC laboratory report for the whole bracelet (one report naming each stone, not one per bead), its own certificate of authenticity, and a photo for your approval before dispatch (checked 3 November 2026). AYU4 has no relationship with it of any kind. Use the same checks with any seller.
Where to buy
If you have decided to buy, choose a seller that gives authenticity you can check yourself: a lab or X-ray report you can verify online. Here are options we can point to; AYU4 takes no commission from any seller.
- GemKrishna: its natural black tourmaline bracelet. A good starting point, which we independently consider a reliable source; AYU4 has no connection to it.
- Rudra Centre: its black tourmaline bracelets. A Mumbai seller, established 1997, that publishes its address, lab certificates and return policy.
- Spiritual and crystal stores near you: fine for common stones, if they name the exact stone, disclose dyeing or heating and give a bill. See what to check.
Judge any seller, including these, with our guides to how to choose a seller and buying crystal bracelets in India, and how to read a gemstone lab report.
Questions readers ask
Does black tourmaline block EMF?
No. There is no evidence that it blocks or absorbs electromagnetic fields from phones or Wi-Fi, and a stone near a device does not change its emissions.
What is black tourmaline good for?
Crystal practice uses it for protection and grounding. There is no evidence of effects beyond expectation.
How can I tell real black tourmaline?
Look for lengthwise striations and a triangular cross-section. Glass and onyx are smooth and uniform.
Can black tourmaline go in water?
Yes, a rinse is safe.
Sources
- Mindat.org: Schorl
- World Health Organization: Electromagnetic fields and public health (mobile phones)
- French C, O'Donnell H, Williams L. Hypnotic susceptibility, paranormal belief and reports of 'crystal healing'. British Psychological Society centenary conference, Goldsmiths, University of London, 2001
A note on health. This guide explains a tradition. It is not medical advice, and nothing in it is a treatment for any disease. See a qualified doctor for symptoms, and do not stop or change a prescribed medicine on the strength of anything you read here. Full medical disclaimer.
