Tourmaline: Properties and ID

Meet October's Birthstone Tourmaline

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tourmaline
Black tourmaline (schorl) collected at the Big Crabtree mine near Spruce P ine, NC.o. Richard Gross

Tourmaline is a generic term that encompasses a group of minerals that is a favorite among mineral collectors and commonly used as a gemstone. Tourmaline gets its name from the Sri Lankan words tur mali which means stone of many colors. Ancient Egyptians believed tourmaline grabbed all the colors of the rainbow as it worked its way up through the earth.

Tourmaline Colors

tourmaline
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One reason for tourmaline’s popularity is its wide array of colors – over 100! The mineral colors are caused by traces of different chemicals. For example, iron produces blue (indicolite) and green colors and manganese produces pink and red colors. Sometimes tourmaline colors are enhanced by heat treatment.

There are five major tourmaline species.

1. Dravite

2. Elbaite – Named after Elba, Italy. Most gem varieties occur in this species.

  • Rubellite – Pink
  • Paraíba (named after Paraíba, Brazil)
  • Watermelon Tourmaline – (red center and green rind)

3. Liddicoatite

4. Schorl – Black (colored by iron)

5. Uvite

tourmaline
This specimen illustrat? the elongated striations on the crystal face typical of tourmaline.
Richard Gross

Tourmaline may form beautiful, elongated crystal clusters that are highly sought after by collectors. It is one of the most prized minerals and stunning specimens can be among the most aesthetic examples in the mineral kingdom.

Tourmaline Facts

Tourmaline has a Mohs hardness of 7.5 and crystallizes in the trigonal system. Most crystals are striated, elongated and prismatic. Vitreous luster and conchoidal fracture are also characteristic. Chatoyancy (cat’s eye effect) is found in some tourmalines.

Besides its use in jewelry, tourmaline becomes electrically charged when it’s heated. Piezoelectric properties can make tourmaline useful in the manufacture of various industrial gauges.

tourmaline
Purple tourmaline from Brazil.
Richard Gross

Confident Tourmaline

In the metaphysical realm, tourmaline is thought to give confidence, relieve nervousness, promote self-assurance, increase physical energy, enhance the immune system, help negate negative thoughts and relieve tension.

Tourmaline is the gemstone for the eighth anniversary and a birthstone for October.

Where to Find

Afghanistan; Australia; Brazil; China; Congo; India; Italy; Kenya; Madagascar; Mexico; Morocco; Mozambique; Myanmar; Namibia; Nepal; Nigeria; Pakistan; Russia; South Africa; Sri Lanka; Sweden; Tanzania; Thailand; United States of America; Urals; Zambia

This story about tourmaline previously appeared in Rock & Gem magazine. Click here to subscribe! Story by Richard Gross and Pam Freeman.

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