Black Tourmaline

Black tourmaline, the variety called schorl, is the iron-rich end of the tourmaline group, a complex boron silicate that forms long striated prisms. Tourmaline is notably pyroelectric and piezoelectric: heated or compressed, a crystal develops opposite electric charges at its two ends, a property Dutch traders in the eighteenth century knew as its habit of attracting and then repelling ash, and which gave it the early name aschentrekker, ash-drawer. That real physical effect is the factual kernel beneath the modern reputation of the stone. In the crystal-healing literature of the late twentieth century onward, black tourmaline is the standard protection and grounding stone and is widely sold for shielding against electromagnetic fields; there is no scientific support for the shielding claim, and the association is a New Age development rather than a traditional attribution.

Schorl, the name for the iron-rich black tourmaline recorded here, is inherited unchanged from Schorl, a village (now Zschorlau) in the Saxon Erzgebirge where tin miners had long found the mineral among their ore; German mineralogists were using the local place name for the stone by the sixteenth century, well before tourmaline as a family was distinguished from other dark crystals. The pyroelectric effect noted above was studied scientifically in the eighteenth century by Franz Aepinus, who in 1756 gave the first physical description of how a heated tourmaline crystal develops opposite charges at its two ends, turning a curiosity of Dutch traders into an object of early electrical science.

Black tourmaline is schorl, the iron-rich end of the tourmaline group, and it is by a wide margin the commonest tourmaline: the great majority of tourmaline in the earth's crust is schorl, and the coloured gem varieties are the exception.

The name is old and industrial rather than ornamental. Schorl is recorded in German mining usage from the fifteenth century, apparently after a village in Saxony near a tin working where the mineral was abundant, and for most of its documented history it was of interest as an unwanted associate of tin ore rather than as anything to be collected. The word tourmaline itself comes from a Sinhala term applied to mixed gem gravels, which entered European use through the Dutch East India trade in the early eighteenth century.

That leaves a gap worth stating directly. Black tourmaline has a substantial place in the modern crystal market, where it is among the most widely sold stones, and it has essentially no pre-modern record as a stone with attributed properties: no classical lapidary entry, no place in the navaratna, no medieval or early modern tradition. Its current reputation was assembled in the twentieth century.

What it does have is physics. Schorl is strongly pyroelectric and piezoelectric, like the rest of the group, and large crystals are common enough to demonstrate it. Whether that property is connected to the modern attributions is a question about the history of an idea, and the atlas records the attributions as modern rather than treating them as inherited.