Tanzanite

Tanzanite is a captivating gemstone known for its striking color and rarity. It is a variety of the mineral zoisite and exhibits a unique blue-violet hue, making it highly sought after in the gemstone market. Tanzanite is found exclusively in a small area near Mount Kilimanjaro in Tanzania, which contributes to its exclusivity and allure. This gemstone has gained immense popularity and significance since its discovery, becoming a symbol of elegance and luxury.

Tanzanite is a member of the epidote mineral group and is scientifically classified as a variety of zoisite. It is renowned for its vivid colors, ranging from deep blue to vibrant violet, often displaying a mesmerizing play of colors due to its trichroic nature. This means that tanzanite can show different colors when viewed from different angles, including blue, violet, and burgundy. The gemstone is prized for its exceptional brilliance and clarity, making it a popular choice for fine jewelry.

Contents

• Discovery and Significance in the Gemstone Market
• Importance of Tanzanite
• Geological Aspects of Tanzanite
• Formation and Composition
• Location and Mining
• Rarity and Exclusivity
• Physical properties
• Optical properties
• Chemical composition
• Major Tanzanite Mining Areas
• Tanzanite uses and applications
• Famous tanzanite jewelry pieces
• Alternatives to Tanzanite
• Summary of key points
• FAQ
• References

Discovery and Significance in the Gemstone Market

Tanzanite was discovered relatively recently in 1967 by a Maasai tribesman named Ali Juuyawatu in the Mererani Hills near Arusha, Tanzania. The gemstone was initially mistaken for sapphire due to its intense blue color. However, after further analysis, it was identified as a new variety of zoisite. Tiffany & Co., a renowned American jewelry company, recognized its potential and introduced it to the global market under the name “tanzanite,” highlighting its unique origin. Since then, tanzanite has become one of the most popular gemstones, particularly in the United States and Europe, with its popularity rivaling traditional gems like sapphire and emerald.

Importance of Tanzanite

Tanzanite’s allure lies in its remarkable color, rarity, and optical properties. Its trichroism, combined with a vivid blue-violet hue, makes it distinct from other gemstones. The depth and richness of its color are unparalleled, often described as a blend of sapphire blue and amethyst purple. Additionally, tanzanite is relatively soft compared to other gemstones, with a Mohs hardness of 6 to 7, requiring careful handling and setting in jewelry. Despite this, its unique color and brilliance continue to captivate gem enthusiasts and collectors worldwide.

Tanzanite plays a crucial role in the economy of Tanzania, as it is the sole source of this gemstone globally. The mining and export of tanzanite contribute significantly to the country’s GDP and provide employment opportunities for thousands of Tanzanians. The government of Tanzania has taken steps to regulate the tanzanite industry to ensure sustainable mining practices and maximize revenue from this precious resource. Additionally, tanzanite has become a symbol of national pride and cultural heritage for the Tanzanian people, attracting tourists and gem enthusiasts to the region.

In conclusion, tanzanite’s unique properties, captivating beauty, and limited availability make it a gemstone of great significance in the global market. Its discovery has not only enriched the world of gemstones but also played a vital role in the economic development of Tanzania. As demand for tanzanite continues to grow, its status as a symbol of elegance and luxury is further solidified, ensuring its place as one of the most treasured gemstones in the world.

Geological Aspects of Tanzanite

Tanzanite is a gemstone that stands out due to its geological formation, composition, and rarity. Its discovery and mining are concentrated in a specific region, adding to its exclusivity and allure in the gemstone market. Here is an in-depth look at the geological aspects of tanzanite:

Formation and Composition

Tanzanite is formed under unique geological conditions that occur only in a small area of northern Tanzania. This region is part of the East African Rift, a tectonically active area that provides the necessary conditions for tanzanite formation. Tanzanite is created when the mineral zoisite is exposed to high temperatures and pressure over millions of years.

The formation process involves the metamorphism of calcium-rich rocks in the presence of vanadium, which gives tanzanite its distinctive blue-violet color. The combination of tectonic activity, specific mineral content, and geological conditions makes tanzanite formation an exceedingly rare occurrence.

Chemical Composition and Physical Properties

Tanzanite is a variety of the mineral zoisite and is chemically classified as a calcium aluminum silicate hydroxide with the formula (Ca(_2)Al(_3)(SiO(_4))(_3)(OH)). Its vibrant color is primarily due to the presence of trace amounts of vanadium within its crystal structure.

Tanzanite has several notable physical properties:

• Trichroism: Tanzanite exhibits trichroism, displaying different colors—blue, violet, and burgundy—when viewed from different angles.
• Hardness: It has a Mohs hardness rating of 6 to 7, making it softer than many other gemstones and requiring careful handling in jewelry settings.
• Cleavage: Tanzanite has perfect cleavage in one direction, meaning it can be easily split along specific planes, which poses challenges in cutting and setting.
• Luster: It possesses a vitreous luster, contributing to its brilliant appearance when polished.

Location and Mining

Tanzanite Mining Regions

Tanzanite is found exclusively in a small region near Mount Kilimanjaro in northern Tanzania, within the Merelani Hills. This area is the only known source of tanzanite in the world, which contributes significantly to its rarity and value.

The mining area is divided into four blocks (A, B, C, and D), each allocated to different mining operations. The largest and most productive of these is Block C, which is mined by large-scale operations, while smaller blocks are mined by artisanal miners.

Methods of Extraction and Challenges Faced in Mining

The extraction of tanzanite involves both large-scale mining operations and small-scale artisanal mining. The methods of extraction include:

• Open-pit mining: This method is used in areas where tanzanite is located near the surface. It involves removing layers of soil and rock to access the gemstone-bearing deposits.
• Underground mining: For deeper deposits, underground mining is employed. This involves tunneling into the earth to reach the tanzanite-bearing veins.

Challenges faced in tanzanite mining include:

• Safety hazards: Mining conditions can be dangerous, with risks of cave-ins and accidents due to the unstable nature of underground tunnels.
• Regulation and legality: Artisanal mining often occurs with limited regulation, leading to illegal mining activities and smuggling.
• Environmental impact: Mining can lead to land degradation and environmental concerns, prompting the need for sustainable mining practices.

Rarity and Exclusivity

Factors Contributing to Tanzanite’s Rarity

Several factors contribute to the rarity of tanzanite:

• Geological exclusivity: Tanzanite is only found in a small region of Tanzania, making it geologically rare compared to other gemstones found in multiple locations.
• Limited supply: The finite nature of tanzanite deposits means that its availability is limited, with estimates suggesting that the current supply may be depleted within a few decades.
• Unique conditions: The specific geological conditions required for tanzanite formation occur in a limited geographic area, further contributing to its rarity.

Comparison with Other Gemstones

Tanzanite is often compared to other blue gemstones like sapphire, but its unique color and properties set it apart. While sapphire is more durable with a higher Mohs hardness of 9, tanzanite’s distinctive trichroic color and rarity make it equally desirable.

In terms of exclusivity, tanzanite is more geographically restricted than most other gemstones, such as diamonds, rubies, and emeralds, which are found in various parts of the world. This exclusivity enhances its allure and makes it a sought-after gem for collectors and jewelry enthusiasts.

In conclusion, tanzanite’s geological formation, unique composition, and limited geographic availability make it a gemstone of exceptional rarity and exclusivity. Its captivating beauty and rich color, combined with its rarity, continue to fuel its demand and value in the global gemstone market.

Physical properties

Tanzanite Crystal 10.38 gram, Mirerani Hills Arusha Tanzania (www.gemrockauctions.com)

1. Color: Tanzanite is renowned for its captivating blue-violet color. The gemstone exhibits a range of shades, from a vibrant blue to a deep violet. The intensity of the color is a crucial factor in determining the value and desirability of Tanzanite.
2. Clarity: Tanzanite can vary in terms of clarity. It may contain inclusions, which are natural internal flaws or tiny mineral crystals within the gemstone. The presence of inclusions can affect the transparency and overall appearance of the stone. Tanzanite with high clarity and minimal inclusions is considered more valuable.
3. Hardness: Tanzanite has a hardness of 6.5 to 7 on the Mohs scale of mineral hardness. This makes it relatively durable and suitable for jewelry use. However, it is important to note that Tanzanite is not as hard as gemstones like sapphires or diamonds, so it requires careful handling and protection to avoid scratches or damage.
4. Crystal Structure: Tanzanite belongs to the orthorhombic crystal system. Its crystals have a prismatic shape with well-defined facets. The crystal structure of Tanzanite contributes to its pleochroism, where the gemstone displays different colors when viewed from different angles.
5. Refractive Index: The refractive index measures how light is bent as it passes through the gemstone. Tanzanite typically has a refractive index ranging from 1.691 to 1.700. This property affects the gemstone’s brilliance and how light interacts with it, contributing to its overall appearance.
6. Specific Gravity: Tanzanite has a specific gravity ranging from 3.35 to 3.38. Specific gravity indicates the density of the gemstone compared to the density of water. This property helps gemologists distinguish Tanzanite from other similar-looking gemstones.
7. Cleavage: Tanzanite exhibits good cleavage, which means it can split along certain planes or directions. Gem cutters need to take this into account when shaping and faceting Tanzanite to minimize the risk of fractures.

Understanding the physical properties of Tanzanite is crucial for evaluating its quality, durability, and overall suitability for different jewelry applications. These properties, along with the gemstone’s remarkable color, contribute to its allure and desirability in the world of gemstones.

Optical properties

The optical properties of Tanzanite play a significant role in its visual appearance and overall beauty. Here are the key optical properties of Tanzanite:

1. Refractive Index: Tanzanite has a refractive index ranging from approximately 1.691 to 1.700. The refractive index determines how much light is bent or refracted as it passes through the gemstone. Tanzanite’s refractive index contributes to its brilliance and sparkle.
2. Pleochroism: Tanzanite is highly pleochroic, meaning it exhibits different colors when viewed from different crystallographic directions. In the case of Tanzanite, it displays a blue hue when viewed from one direction, violet from another, and sometimes even a burgundy color from a different angle. The pleochroic effect adds depth and interest to the gemstone’s appearance.
3. Birefringence: Tanzanite has a relatively high birefringence due to its orthorhombic crystal structure. Birefringence refers to the difference in refractive indices between two perpendicular crystallographic directions. In Tanzanite, this property can result in a doubling of facets or edges when viewed through the gemstone, a phenomenon known as doubling.
4. Dispersion: Tanzanite exhibits moderate to high dispersion, which refers to the ability of a gemstone to separate white light into its spectral colors or fire. The dispersion in Tanzanite contributes to the play of colors and adds to its visual appeal.
5. Transparency: Tanzanite is typically transparent to translucent, allowing light to pass through the gemstone with minimal obstruction. High-quality Tanzanite with good transparency allows for excellent light transmission, enhancing its brilliance and color display.
6. Luster: Tanzanite exhibits a vitreous to subadamantine luster, giving it a desirable and reflective shine. The gemstone’s luster adds to its overall attractiveness and visual appeal.

Understanding the optical properties of Tanzanite is crucial for gemologists, jewelers, and gemstone enthusiasts. These properties influence the way light interacts with the gemstone, affecting its color display, brilliance, and visual effects such as pleochroism and dispersion. It is these optical characteristics that make Tanzanite a captivating and sought-after gemstone.

Chemical composition

Tanzanite is a variety of the mineral zoisite, which belongs to the epidote mineral group. The general chemical formula for zoisite is Ca2Al3(SiO4)(Si2O7)O(OH). However, Tanzanite contains additional elements that give it its distinct blue-violet color. The blue coloration is primarily due to the presence of trace amounts of vanadium (V), while the violet color is attributed to the presence of chromium (Cr). The specific chemical composition of Tanzanite can be expressed as (Ca2Al3(SiO4)(Si2O7)O(OH)) with vanadium and chromium impurities.

It’s important to note that the presence of these impurities, particularly vanadium and chromium, is responsible for the exceptional coloration of Tanzanite. The combination of these elements in the crystal lattice of Tanzanite gives it its unique blue and violet hues, which are highly prized in the gemstone world.

The chemical composition of Tanzanite provides valuable insights into its mineralogical classification and the elements responsible for its remarkable color. Understanding the presence of vanadium and chromium helps gemologists and scientists identify and distinguish Tanzanite from other similar gemstones.

Major Tanzanite Mining Areas

The Merelani mining area is divided into four primary blocks, labeled A, B, C, and D, each with distinct characteristics and ownership structures. Here is a breakdown of these major mining areas:

Block A

• Ownership and Operations: Block A is predominantly mined by small-scale artisanal miners. It consists of numerous small plots worked by individuals or small groups, with limited mechanization and infrastructure.
• Characteristics: Mining in Block A is often informal, with miners using basic tools and techniques. This block yields a variable quality of tanzanite, and miners face challenges such as unsafe working conditions and limited access to resources.

Block B

• Ownership and Operations: Similar to Block A, Block B is also worked by artisanal miners. It is characterized by small, independent mining claims operated by local miners.
• Characteristics: The mining operations in Block B are typically low-tech and labor-intensive. Miners in this area often struggle with issues related to safety, legality, and market access for their finds.

Block C

• Ownership and Operations: Block C is the largest and most productive of the Merelani mining areas. It is primarily operated by TanzaniteOne Mining Limited, a large-scale commercial mining company that employs modern mining techniques and equipment.
• Characteristics: This block has the most advanced infrastructure and yields the highest quality and quantity of tanzanite. TanzaniteOne Mining Limited is known for its efforts to implement sustainable mining practices and improve the working conditions and welfare of its employees.

Block D

• Ownership and Operations: Block D, like Blocks A and B, is mainly mined by artisanal miners. However, it has seen increased activity from small to medium-scale mining operations as well.
• Characteristics: The area is characterized by varied mining techniques, with both manual and mechanized methods employed. Miners in Block D face similar challenges to those in Blocks A and B, including safety concerns and market access difficulties.

It’s important to note that Tanzanite mining is subject to regulations and oversight by Tanzanian authorities to ensure responsible and sustainable practices. Efforts are made to address environmental concerns, support local communities, and prevent illegal mining and trade of Tanzanite.

Tanzanite uses and applications

Tanzanite is a versatile gemstone that finds applications in various areas. Here are some common uses and application areas of Tanzanite:

1. Jewelry:
   • Tanzanite is primarily used in jewelry and is highly valued for its exceptional color and rarity.
   • It is often cut and faceted into various shapes, including round, oval, cushion, and pear, to create exquisite pieces of jewelry such as rings, earrings, necklaces, bracelets, and pendants.
   • Tanzanite jewelry is cherished for its vibrant blue-violet hues, which can range from intense blue to deep violet, making it a captivating gemstone for both casual and formal occasions.
2. Collectibles and Investment:
   • Tanzanite’s limited supply and rarity make it an attractive gemstone for collectors and investors.
   • High-quality Tanzanite gemstones with desirable color, clarity, and size are highly valued and can appreciate in value over time.
   • Collectors often seek unique and rare Tanzanite specimens or gemstones with exceptional characteristics, such as large sizes, exceptional color saturation, or outstanding clarity.
3. Fashion and Accessories:
   • Tanzanite can be used in fashion and accessories beyond traditional jewelry.
   • It can be incorporated into designer pieces, such as brooches, hair accessories, or cufflinks, adding a touch of elegance and sophistication.
   • Tanzanite beads or cabochons can also be used in textile embellishments, embroidery, or as decorative elements in high-end fashion.

It’s important to note that while Tanzanite has various applications, it should be handled and cared for with caution. Due to its moderate hardness, Tanzanite can be susceptible to scratches and damage if not handled properly. It is advisable to remove Tanzanite jewelry when engaging in activities that may subject it to potential impact or abrasion.

Overall, Tanzanite’s exceptional beauty and rarity have made it a sought-after gemstone in the world of jewelry, collecting, and metaphysical practices. Its vivid blue-violet color and unique properties continue to captivate gemstone enthusiasts and consumers alike.

Famous tanzanite jewelry pieces

There are several famous Tanzanite jewelry pieces that have gained recognition for their beauty, craftsmanship, and historical significance. Here are a few notable examples:

1. The Queen of Kilimanjaro:
   • The Queen of Kilimanjaro is one of the most famous Tanzanite jewelry pieces.
   • Created by renowned jewelry designer Michael Scott, this necklace features a 242-carat Tanzanite as its centerpiece.
   • The necklace also incorporates over 100 carats of diamonds set in platinum.
   • The Queen of Kilimanjaro was unveiled in 1988 and has since become an iconic representation of Tanzanite’s allure.
2. The Midnight Star:
   • The Midnight Star is an exquisite Tanzanite ring owned by actress Elizabeth Taylor.
   • The ring showcases a remarkable 116-carat cushion-cut Tanzanite surrounded by 16 carats of diamonds.
   • This stunning piece was gifted to Elizabeth Taylor by her husband Richard Burton and became a cherished part of her jewelry collection.
3. The Grandidierite Necklace:
   • Designed by Tiffany & Co., the Grandidierite Necklace features a rare 115-carat grandidierite gemstone as its focal point.
   • The necklace also incorporates Tanzanite gemstones, diamonds, and platinum.
   • The unique combination of the rare grandidierite gemstone and Tanzanite creates a captivating and distinctive piece of jewelry.
4. The Greenbrier Tiara:
   • The Greenbrier Tiara is a magnificent headpiece commissioned by the Greenbrier Resort in West Virginia, USA.
   • The tiara showcases several gemstones, including a large pear-shaped Tanzanite, surrounded by diamonds and set in platinum.
   • This regal and elegant tiara has become an iconic symbol of luxury and glamour.

These famous Tanzanite jewelry pieces have not only showcased the beauty and allure of Tanzanite but have also played a role in raising awareness and appreciation for the gemstone. They exemplify the exceptional craftsmanship and artistry that goes into creating exquisite jewelry pieces featuring Tanzanite as the centerpiece.

The Queen of Kilimanjaro

Alternatives to Tanzanite

While Tanzanite is a unique and captivating gemstone, there are several alternatives available that offer similar colors or characteristics. Here are some popular alternatives to Tanzanite:

1. Blue Sapphire:
   • Blue sapphire is a gemstone known for its rich blue color, making it a close alternative to Tanzanite.
   • Sapphires are durable and come in a range of blue shades, from deep navy to lighter blue hues.
   • They are widely used in jewelry, including rings, earrings, and pendants.
2. Blue Topaz:
   • Blue topaz is a more affordable alternative to Tanzanite and is available in various shades of blue, including light sky blue and vibrant Swiss blue.
   • Blue topaz is a popular gemstone for both casual and formal jewelry designs.
   • It is often used as a more budget-friendly option to achieve a similar blue gemstone look.
3. Iolite:
   • Iolite, also known as “water sapphire,” can resemble Tanzanite in its blue-violet coloration.
   • Although it is less commonly used, iolite is a beautiful gemstone with a unique bluish-violet hue and good clarity.
   • It can be an alternative choice for those seeking a similar color range as Tanzanite.
4. Amethyst:
   • Amethyst is a purple gemstone that can be a more affordable substitute for the violet hues of Tanzanite.
   • While it does not possess the blue tones of Tanzanite, it offers a range of purple shades from light lavender to deep violet.
   • Amethyst is widely used in jewelry and is often seen in rings, earrings, and necklaces.
5. Lapis Lazuli:
   • Lapis lazuli is a deep blue gemstone with specks of golden pyrite and occasional white calcite veins.
   • It has been used for centuries in jewelry and art and can be an alternative for those seeking a vivid blue gemstone with a unique appearance.

It’s important to note that while these gemstones share some similarities with Tanzanite in terms of color, they may differ in other characteristics such as hardness, brilliance, and rarity. When considering alternatives to Tanzanite, it’s advisable to choose a gemstone that aligns with your preferences, budget, and desired qualities.

Summary of key points

• Tanzanite is a rare and valuable gemstone that is renowned for its blue-violet color, ranging from intense blue to deep violet.
• It is a variety of the mineral zoisite and is found exclusively in the Merelani Hills of northern Tanzania.
• Tanzanite is notable for its pleochroism, meaning it can exhibit different colors when viewed from different angles.
• The gemstone’s physical properties include a hardness of 6.5 to 7 on the Mohs scale and a specific gravity ranging from 3.35 to 3.55.
• Tanzanite’s optical properties include strong trichroism, high refractive index, and vitreous to sub-adamantine luster.
• Its chemical composition consists of calcium, aluminum, silicon, oxygen, and traces of vanadium, which is responsible for its unique blue-violet color.
• Tanzanite is primarily used in jewelry, and it is commonly featured in rings, earrings, necklaces, pendants, and bracelets.
• Some famous Tanzanite jewelry pieces include the Queen of Kilimanjaro, the Midnight Star ring, the Grandidierite Necklace, and the Greenbrier Tiara.
• Alternatives to Tanzanite include blue sapphire, blue topaz, iolite, amethyst, and lapis lazuli.
• Tanzanite mining takes place in the Merelani Hills, and the production process involves extraction, sorting, processing, cutting, polishing, and the creation of finished jewelry.
• Tanzanite is associated with various metaphysical properties and is believed to promote spiritual growth, intuition, and emotional balance.

Tanzanite’s exceptional beauty, rarity, and captivating color have made it a highly sought-after gemstone in the world of jewelry and collectibles.

FAQ

How is Tanzanite formed?

Tanzanite is formed through a combination of geological processes. It is believed to have originated from the metamorphism of a specific type of igneous rock called “blue zoisite.” The rock undergoes heat and pressure deep within the Earth’s crust, causing chemical changes that transform it into Tanzanite.

Where is Tanzanite found?

Tanzanite is found exclusively in a small region of northern Tanzania, near the foothills of Mount Kilimanjaro. The primary mining area is the Merelani Hills, located near the town of Arusha. This area is the only known source of Tanzanite in the world.

What makes Tanzanite rare?

Tanzanite’s rarity is due to its limited geographic occurrence. It is found in a single location in northern Tanzania, making it a geologically scarce gemstone. Additionally, the mining of Tanzanite is challenging and complex, further contributing to its rarity.

What gives Tanzanite its color?

Tanzanite’s stunning blue-violet color is attributed to the presence of trace amounts of vanadium within the gemstone. The interaction of vanadium with the crystal structure of Tanzanite produces its unique color range, from blue to violet, depending on the lighting conditions and viewing angles.

How old is Tanzanite?

Tanzanite is relatively young in terms of geological age. It is estimated to be around 585 million years old, which is considered young compared to other gemstones like diamonds or rubies. Tanzanite’s formation occurred during tectonic activities that shaped the region’s geology.

Can Tanzanite be found anywhere else?

As of the current knowledge and available information, Tanzanite is found exclusively in the Merelani Hills of Tanzania. Extensive exploration efforts have been made, but no other significant sources of Tanzanite have been discovered elsewhere in the world.

References

1. Fritsch, E., & Shigley, J. E. (1991). Tanzanite: Born from Lightning. Gems & Gemology, 27(4), 262-277.
2. Rossman, G. R., & Mielke, R. E. (1993). Blue coloration of tanzanite by intervalence charge transfer: A UV-VIS-NIR and IR study. American Mineralogist, 78, 439-444.
3. Laurs, B. M. (2005). The rise of tanzanite: How an extraordinary gemstone came to market. Gems & Gemology, 41(2), 100-119.
4. Pardieu, V., & Saul, M. (2010). Tanzanite deposits of Merelani. In G. Blanco-Moreno, T. S. Hayes, & J. J. Griffin (Eds.), Geology and Mineral Resources of the Kilimanjaro Region: A Modern Synthesis of Classic Studies (pp. 99-110). Geological Society of America Special Paper 461.
5. Gems & Gemology Magazine. (Various issues). Gemological Institute of America.