Short answer: black tourmaline, called schorl, is the most common kind of tourmaline, a hard boron silicate mineral that grows as long, striated crystals with a distinctive three-sided cross section. Tourmaline comes in almost every color, from black to pink, green and watermelon. In crystal traditions, black tourmaline is one of the best-known stones of protection and grounding.
What is tourmaline?
Tourmaline is not one mineral but a group of closely related boron silicate minerals with a complex chemistry. Different members of the group, and different trace elements, give it a range of color matched by few other gems. It rates 7 to 7.5 on the Mohs scale, hard enough for everyday jewelry, and it is the October birthstone.
What is black tourmaline?
Black tourmaline is schorl, the sodium and iron rich member of the tourmaline group. It is by far the most common tourmaline, possibly 95 percent or more of all tourmaline in nature. It is opaque and glossy black, and it is collected as crystals and specimens rather than cut as a gem.
Schorl is common in granite and granite pegmatites. Crystals often sit in white quartz or feldspar, and slender black needles of tourmaline inside clear quartz are sold as tourmalinated quartz.
How do you recognize tourmaline crystals?
Tourmaline has an unusual shape that makes it easy to identify.
- Three-sided prisms. Tourmaline crystals are usually triangular in cross section, with curved, rounded sides. No other common mineral forms three-sided prisms.
- Lengthwise striations. Fine grooves run down the length of the crystal faces.
- Long, slender crystals, from thin needles to thick columns, often in radiating sprays.
- Different ends. The two ends of a crystal are often shaped differently, a feature called hemimorphism.
Tourmaline and electricity
Tourmaline is piezoelectric, meaning a crystal develops an electric charge when it is squeezed, and pyroelectric, meaning it becomes charged when it is warmed or cooled. When warmed, it can attract and then repel light ash, which earned it the old nickname "Ceylonese magnet". In the 19th century, chemists used tourmaline to polarize light.
What colors and varieties are there?
- Black (schorl) is the most common.
- Pink and red (rubellite) is the traditional October birthstone color.
- Green, including deep green chrome tourmaline.
- Watermelon tourmaline is pink at the core and green on the outside.
- Blue (indicolite) and the neon blue to green, copper-bearing Paraíba tourmaline are among the most valuable.
- Brown to yellow (dravite) is the magnesium-rich member, found mostly in schist and marble.
The October birthstones guide covers gem tourmaline, its history and Paraíba tourmaline in more detail.
Where does tourmaline come from?
Tourmaline is found in granite and granite pegmatites, and in metamorphic rocks such as schist and marble. Schorl and the colorful lithium-rich tourmalines usually grow in granite and pegmatite; the pegmatite guide explains how those rocks grow large crystals. Brazil is the leading source of gem tourmaline. Other sources include Afghanistan, Pakistan, Kenya, Madagascar and Mozambique, and in the United States, Maine and California.
Tourmaline in history
Colorful tourmaline from Sri Lanka, then Ceylon, reached Europe in quantity through the Dutch East India Company, which shipped it to satisfy a demand for curiosities and gems. For centuries it was confused with other stones: a Spanish conquistador who found green tourmaline crystals in Brazil in the 1500s took them for emeralds, and one of the "rubies" in the Russian crown jewels, the Caesar's Ruby pendant, is red tourmaline. Scientists recognized tourmaline as a distinct mineral species only in the 1800s, around the time that chemists began using thin tourmaline plates to polarize light. In the United States, the first tourmaline was found in 1821 on Mount Mica in Paris, Maine.
What is black tourmaline traditionally associated with?
In modern crystal traditions, black tourmaline is one of the stones most associated with protection, grounding and a sense of security. It is often placed near doors and in workspaces, and it is commonly linked with the root chakra. Some lists pair it with Capricorn. GIA notes that black tourmaline is believed to protect the wearer and give a sense of confidence, while pink tourmaline is associated with love and compassion and green with courage and strength.
These are traditions and beliefs. They are part of why people choose tourmaline, not properties you can measure in the stone.
Raw, tumbled and polished tourmaline
Raw black tourmaline is sold as single crystals, clusters, crystals in quartz matrix and rough chunks, all showing its striated faces. Tumbled stones and palm stones are glossy black. Towers and spheres are cut from massive schorl. Colored tourmaline appears as crystals, slices, and faceted and cabochon gems. Because schorl crystals are brittle and often cracked across their length, raw pieces can break along those cracks.
Tourmaline jewelry
At 7 to 7.5 on the Mohs scale, gem tourmaline suits rings, earrings and pendants. Black tourmaline is used in beads and in raw-crystal pendants, which are more fragile than polished stones.
How do you care for tourmaline?
- Clean it with warm, soapy water and a soft brush, then dry it.
- Do not use ultrasonic or steam cleaners, and keep it away from high heat.
- Handle raw crystals gently. Schorl is brittle and often cracked across the crystal.
- Store it apart from softer stones, which it can scratch.
How can you tell real black tourmaline?
- Look for striations running along the crystal and a rounded triangular cross section.
- Hardness: tourmaline scratches glass.
- Black obsidian and dyed or plastic imitations lack the striated, three-sided crystal form. Obsidian is glassy with curved, shell-like breaks and no striations.
- Weight: tourmaline is noticeably heavier than plastic.
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Frequently asked questions
What is black tourmaline traditionally associated with?
In crystal traditions it is a stone of protection and grounding, often kept near doors and linked with the root chakra. These are traditional meanings rather than measurable properties.
Is black tourmaline the same as schorl?
Yes. Schorl is the mineral name for black tourmaline, the sodium and iron rich member of the tourmaline group and by far the most common tourmaline.
Can black tourmaline get wet?
Yes. Tourmaline is hard and not water soluble, so it can be rinsed or washed with mild soap and dried. Raw crystals with cracks are best wiped rather than soaked.
How do you identify tourmaline?
By its long crystals with fine lengthwise grooves and a rounded, three-sided cross section. No other common mineral forms three-sided prisms.
Is tourmaline a birthstone?
Yes. Tourmaline is one of the October birthstones, with pink tourmaline the traditional October color.
Sources
- Wikipedia, Tourmaline: https://en.wikipedia.org/wiki/Tourmaline
- GIA, Tourmaline: https://www.gia.edu/tourmaline
- GIA, October Birthstones: https://www.gia.edu/birthstones/october-birthstones
- Wikipedia, Pyroelectricity: https://en.wikipedia.org/wiki/Pyroelectricity