Black Opal and Rubellite Tourmaline
I’m married to a man born in October, and I can testify that he’s complicated. But I never thought October’s two birthstones had unusual complexity to them until I started to really study them. Tourmaline has a complex physical nature while Opal has a complex history and symbolic nature. Let’s see if light can be shed on these two amazing gems.
Tourmaline wasn’t recognized as a separate group of minerals until the 1800s. It comes in an unbelievable array of colors, so chrome tourmaline was often mistaken for emerald. Rubellite tourmaline was thought to be ruby. Back in the days before modern mineralogy, gem stones were often identified by their color. Chemically, tourmaline is complicated because many of its elements have the ability to replace one another in a process called isomorphous replacement. That’s why tourmaline from the Paraiba mine in Brazil can be neon blue. Copper is part of its chemical makeup. That’s why chrome tourmaline from Tanzania can be a deep, almost emerald green. Chromium is part of its formula. Pink tourmaline from Zambia has magnesium and black tourmaline (also called schorl) has iron. These gems all have the same basic chemical formula, but it’s a formula that allows for lots of substitutions.
The crystal habit of tourmaline is a unique 3-sided column, with cross sections that resemble rounded triangles. It’s not uncommon to see different colors evident in the same crystal, leading to bi- and tri-colored tourmaline. There’s even watermelon tourmaline which has cross sections that show pink centers and green boundaries. The value of tourmaline is complicated, too. A high quality Paraiba tourmaline sells for tens of thousands of dollars per carat. A large piece of black tourmaline sells on Amazon for under $10.
Paraiba tourmalines photographed from the GIA Collection for the CIBJO project from the Dr. Eduard J. Gubelin Collection.
What’s quite complex about opal is its reputation. It falls in and out of favor, depending on who writes about it, who wears it, and what superstitious stories are made up about it. From ancient mythology, the opal was said to be a symbol of purity, hope, and innocence. It was supposed to be protection against evil. But, during the Black Plague of the 14th century, opal wearers often died. The rumor circulated that it was the opal that caused death. Opals were evil! In the 1500s opinion changed. Shakespeare wrote about opal as the “queen of gems.” It became popular once again. But, in the early 1800s, Sir Walter Scott wrote a book whose character, Lady Hermione, dies soon after a drop of holy water destroys her opal’s colors. It’s uncertain what caused Hermione’s death, but the opal market was clearly dead for 50 years because of Sir Walter Scott’s book.
In 1877, an amazing Australian black opal was discovered, and Queen Victoria decided that she liked opals. Opals were good! She gave one to each of her five daughters, and her love of it made the gem popular again. Today, opals still swim in complexity. Sometimes I’ll hear customers talk about the superstition of opal only being good luck to those born in October. Or they’ll talk about Sir Walter Scott’s book. But my opal has never brought me anything but joy–and I was born in June!
If you’re born in October, be proud of the fact that your birthstones are complicated. It’s much more interesting than perfect clarity! Embrace the mystery.