Afghanistan Tourmaline

Afghanistan is known for producing blue tourmaline and sea foam green tourmaline. In fact Afghanistan has produced thousands of carats of gem-quality tourmaline since 1970. Tourmaline gems from Afghanistan have astonishing array of colors. Tourmaline crystals have various shade of pink, blue, green, and multi-colored. The colors of blue and green tourmaline vary somewhat in different mines. Their color varieties are from grayish blue, greenish blue, to intense blue, and from bluish green, grass green, to bright blue green. Afghanistan multi-colored tourmaline is very spectacular when displays sharp color transitions of pastel pink, yellow, and grass green. Mostly tourmalines were mined out of pegmatite pockets in Nuristan region. The recent discoveries are the fields in Laghman, Kunar province, Nuristan region.

Chrome Tourmaline

Chrome tourmaline has a rich green color. Fine chrome tourmaline with bluish green tone can comparable to emerald. Finest yellowish green chrome tourmaline is difficult to distinguish from tsavorite. Even experienced dealers may have to confirm their judgment by the aid of a gemological instrument.

The rich green color is produced by chromium and vanadium chemical compositions. Chrome tourmaline is dravite or uvite tourmaline variety and comes from a few East African countries, primarily Kenya and Tanzania.

Canary Tourmaline

Canary Tourmaline is the marketed name of yellow or bright golden tourmaline. The main source of canary tourmaline is in the border between Malawi and Zambia. Yellow tourmaline was extracted from alluvial deposit which contains magnesium element. Electric yellow color of canary tourmaline was achieved by heat treatment to drive out secondary colors. As yellow tourmaline has green or brown as secondary color. Yellow tourmaline is also found in Nigeria, Tanzania, and etc but not in large quantity as the find in Zambia.

Schorl Tourmaline

Schorl tourmaline is the black, iron-rich variety of tourmaline, and is the most common varieties of tourmaline. Schorl tourmaline crystals are opaque. Schorl tourmaline has found in many localities but few for fine crystals are from Germany, Italy, Russia, USA, Namibia, and Afghanistan.

Cat’s Eye Tourmaline

Cat’s eye tourmaline is a tourmaline with parallel microscopic inclusions that reflect light, producing the cat’s-eye effect. Cat's-eye tourmaline is found in a variety of colors and is generally semi-translucent to opaque. Usually white, pink, and blue cat’s-eye tourmaline is less difficult to find than green colors. Prices of cat's-eye tourmaline will depend on color, translucency, size and the sharpness of the white eye.

Liddicoatite Tourmaline

Liddicoatite tourmaline is a large multi-colored tourmaline with the beautiful symmetrical colors zoning. Liddicoatite tourmalines were produced from the Anjanabonoina pegmatite deposit in central Madagascar. This tourmaline usually found with zoned green, pink, and red colors. To best display its complex color zoning and patterns, the tourmaline is commonly sold as polished slices or carvings.

Liddicoatite Tourmaline from Madagascar. Photo by gia.edu

Color-change Tourmaline

One of rare tourmalines is color-change tourmaline or alexandrite-like tourmaline. This gem may look green, yellowish green, or brownish green in daylight and brown red or red under incandescent light. Color-change tourmaline is dravite & uvite mixed crystals and found in East Africa.

Usambara Effect Chrome Tourmaline

In the early 1990s Norwegian geologist Asbjorn Halvorsen collected beautiful samples of chromiferous green tourmaline in the Nchongo area of the Umba Valley of Tanzania. The nature of this particular tourmaline was something altogether new. The single crystal appears green in normal lighting, but when a single light source is transmitted through the crystal, it exhibits a color shift from green to red when the crystal reaches a certain thickness, while less thick areas remain green. This color change has been called "Usambara effect", after the nearby Usambara Mountains where this material is found.

Unlike the "alexandrite effect", where the color change dependent on the type of lighting, the "Usambara effect" describes a color change dependent on a change of path length of light through the gem. When the light path reaches a critical length, the perceived color of the transmitted light suddenly shifts from green to red. With increased path length, the intensity of the red is increased and the intensity of the green diminishes.

pic from: nordskip.com, Photo: Jan Kihle at Institute for Energy Technology courtesy of Asbjorn Halvorsen
Usambara effect chrome tourmaline in transmitted light. Notice the abrupt change to red marking the critical thickness change-over point.

Besides tourmaline, the Usambara effect has been observed in several other gems including garnet, sapphire, and alexandrite.

Achroite Tourmaline

Achroite tourmaline is a variety of elbaite tourmaline. Achroite tourmaline is a colorless tourmaline. An achroite tourmaline rough may look in pale orange or brown color. This tourmaline does not show the strong dichroism characteristic of most tourmaline varieties. Achroite tourmaline is rare and is a collector’s gem. However, colorless tourmaline or white tourmaline may also be produced by the unexpected results of heating tourmaline.

Trapiche Tourmaline

Trapiche tourmaline is a phenomenal gem. Trapiche structure was never known to exist in tourmaline until 2007 there was a first discovery of trapiche tourmaline crystals from Zambia.

Trapiche Tourmaline crystals from Zambia show a growth pattern reminiscent of trapiche emerald/ruby when sliced perpendicular to the c-axis.

Trapiche Tourmaline Crystals from Zambia

In contrast to trapiche emeralds the center of Zambia trapiche tourmaline is subdivided into three sectors with black inclusions forming a motif. Numerous hollow tubes have been observed which are oriented parallel to the optic axis in the center and perpendicular to the former in the outer sectors. The black inclusions that also partially fill the hollow tubes consist mostly of graphite.

Zambia trapiche tourmaline is uvite that is colored green by a vanadium-related mechanism.

Related Tourmaline Gemstone Information

• Pink Tourmaline Gemstone Information
• Blue Tourmaline Gemstone Information
• Green Tourmaline Gemstone Information