The Northern Lights in a Gemstone

BY STEVE VOYNICK

The northern lights are an awesome celestial display; the mineralogical phenomenon that best replicates their splendor is labradorescence. Courtesy Wikimedia Commons

The northern lights, those glowing curtains of cyan, green, gold and magenta that brighten the night skies in the northern latitudes, are among nature’s most stunning displays of color. The mineralogical phenomenon that best replicates this celestial splendor is labradorescence—the multicolored, subsurface, iridescent sheen that characterizes fine specimens of labradorite.

Labradorite’s classic source—its geologic type locality, namesake, and the birthplace of its legends—is the remote coast of Labrador, the northern part of the Canadian province of Newfoundland and Labrador. Labrador is named for the Portuguese mariner Joāo Fernandes Lavrador who, in 1498, braved the region’s subarctic climate to explore its rugged, deeply indented coast.

“FIRESTONE”

In 1771, Moravian missionary Jens Haven founded the coastal settlement of Nain in northern Labrador. Intrigued by the brightly colored stones displayed by the indigenous Inuit, Haven sent specimens to Germany where they became known as “Labrador Stein,” and to England where they were called “Labrador stone” and “firestone.”

As the first new mineral reported from what would become Canada, Haven’s specimens, with their eyecatching colors, attracted great scientific attention in Europe. In 1780, German geologist Abraham Gottlieb Werner, unable to determine the composition of Labrador Stein, erroneously described it as a distinct mineral species.

The first clue toward understanding the chemistry of “firestone” came in 1820, when researchers described the plagioclase feldspar minerals albite (sodium aluminum silicate) and anorthite (calcium aluminum silicate). Soon afterward, French mineralogist François-Sulpice Bedant determined that the Labrador specimens were a type of feldspar with characteristics of both anorthite and albite and named them “labradorite.”