Midnight Tourmaline are beautiful, pure black gemstones from Brazil’s famous Sapo Mine. Enjoying a revival due to the popularity of Black Diamonds, Midnight Tourmaline of a fine quality is increasingly scarce.
Hardness 7 - 7.5
Refractive Index 1.624 - 1.644
Relative Density 2.82 - 3.32
Aptly named Midnight Tourmaline due to its striking pure black hue, this gem is also known as Black Tourmaline or Schorl (the old German name for this gemstone). Medieval records show the village of Zschorlau in Saxony, Germany was originally named ‘Schorl’ prior to 1400, due to Midnight Tourmaline being found in a nearby tin mine.
An important gemstone in Victorian mourning jewelry, Midnight Tourmaline is enjoying a revival due to the increasing popularity of opaque black gemstones. Driven by the demand for Black Diamonds, Midnight Tourmaline is an affordable alternative that can be polished to a much higher luster than other black gemstones such as Jet, Obsidian or Onyx.
Midnight Tourmaline’s main value determinants are a pure pitch black color, smooth surfaces with a high luster, and cutting quality. Due to the opacity of Midnight Tourmaline, a superior polish that maximizes the gems’ signature luster is absolutely critical; very rarely do we find such perfect Midnight Tourmaline.
Rich in iron, Midnight Tourmaline can also be magnetic. When Midnight Tourmaline is found as long and thin crystal inclusions in Quartz, the gemstone known as Tourmalinated Quartz is created.
Tourmaline frequently garners the nickname, ‘the chameleon gem’, not only because of its multitude of colors, but also because of its historic propensity to be confused with other gemstones. Tourmaline is derived from the Sinhalese ‘turmali’, which means ‘mixed parcel’ or ‘stone with mixed colors’ and are a group of related minerals whose differences in composition result in a huge variety of colors. While there are 13 mineralogical varieties of Tourmaline, Elbaite is the mainstay of Tourmaline gemstones. Elbaite is named after the island of its discovery (Elba) in Tuscany, Italy; Elba is best known as the island of Napoleon’s exile in 1814. Tourmaline’s different colors are either identified by a color prefix, such as blue-green, green and pink, or a variety name or prefix. These include Bi Color Tourmaline (two or more colors), Canary Tourmaline (intense yellow from the African nations of Malawi and Zambia), Cat’s Eye Tourmaline (chatoyant Tourmaline), Color Change Tourmaline (green to red), Cuprian Tourmaline (non-Paraíba hues including purples, but still colored by copper and manganese), Indicolite (blue), Paraíba Tourmaline (blue to green, colored by copper and manganese), Rubellite (red), and Watermelon Tourmaline (pink interior, green exterior, just like the fruit). Another prized, but exceedingly rare variety is Chrome Tourmaline, a vivid pure green East African Dravite colored by chromium and vanadium, the same elements that color Emerald and Tsavorite. Last is Midnight Tourmaline (Schorl), a variety once popular in mourning jewelry that is enjoying a revival due to the popularity of Black Diamonds.
Discovered on seven continents, Midnight Tourmaline’s most notable locations are Brazil, Pakistan and Namibia. The most abundant Tourmaline color, Black Tourmaline may account for 95 percent or more of all Tourmaline found in nature. Despite this natural occurrence, Midnight Tourmaline is very rarely found perfectly black with smooth surfaces suitable for gemstones.
Tourmaline was discovered in Brazil by the Portuguese in the 16th century at the gem fields of Minas Gerais (English: General Mines). Midnight Tourmaline is from the famous Sapo Mine in the Doce Valley of the Brazilian state of Minas Gerais. Yielding Midnight Tourmaline of a fine quality, the Sapo Mine works a thick sub-horizontal pegmatite (intrusive igneous rocks composed of interlocking crystals) that was discovered in 1985 after a local farmer found signs of Green Tourmaline outside an ant colony on the other side of the hill from the present Sapo Mine. Later some garimpeiros (itinerant miners) obtained permission to dig on the other side of the hill, discovering the Sapo pegmatite. The mine was named Sapo (frog) due to its proximity to a marsh, which is home to a variety of frogs.
The Sapo Mine is renowned for its rich variety of minerals, especially Tourmaline, and is a significant producer of this important Brazilian gemstone. The mine has produced large pockets of Quartz crystals, several important pockets of Tourmaline and, in 2009, two large cavities containing excellent crystals of Apatite where unearthed. The Horacio Creek runs through the marsh and flooding during the rainy season limits mining.
Commercially scarce because it is rarely faceted, Midnight Tourmaline demand has increased due to the resurgence in popularity of opaque black gemstones, further decreasing the availability of top quality gems in the marketplace. With over 90 percent of gemstones treated, Midnight Tourmaline is one of the few gemstones that are not enhanced.
Durability & Care
Midnight Tourmaline is a durable gemstone (Mohs’ Hardness: 7 – 7.5) well-suited to everyday wear. Always store Midnight Tourmaline carefully to avoid scuffs and scratches. Clean with gentle soap and lukewarm water, scrubbing behind the gem with a very soft toothbrush as necessary. After cleaning, pat dry with a soft towel or chamois cloth.