Tsavorite: Gemstone, Properties, Value

Tsavorite is a rare and stunning variety of garnet. Tsavorite is a rare variety of grossular garnet, known for its intense green color caused by traces of vanadium. Discovered in the 1960s in Tanzania, it quickly gained popularity for its beauty and durability.

Tsavorite, also known as Tsavolite, is a stunning variety of the garnet family, specifically a calcium-aluminum garnet called grossular. It's renowned for its vibrant and captivating emerald-green hues, ranging from a fresh spring green to a deep, rich forest green, often with hints of blue.

Discovered in 1967 in Tanzania, it quickly gained popularity for its brilliance, fire, and durability, making it a sought-after gemstone for jewelry.

The name "tsavorite" is derived from Tsavo National Park in Kenya, where the gemstone was first discovered.

Tsavorite is considered a birthstone for January.

Rough and cut Tsavorite from Merelani, Tanzania

Tsavorite Properties

Color: Tsavorite boasts a vibrant emerald green color, ranging from a fresh spring green to a rich, bluish-green, and even deep forest-green. This vibrant hue is due to trace amounts of vanadium or chromium.

Brilliance: Tsavorite boasts a high refractive index, leading to dazzling brilliance and fire. Its dispersion, the separation of light into different colors, adds to its vibrant sparkle.

Hardness: 7-7.5 on the Mohs scale, making it durable for jewelry use.

Crystal system: Cubic, often forming in dodecahedral or trapezohedral crystals.

Refractive Index: 1.734-1.759, resulting in high brilliance and dispersion, allowing light to play beautifully within the stone.

Rarity: Tsavorite is considered one of the rarest and most valuable garnet varieties. Its primary source is in the Tsavo region of Kenya, making it a coveted gemstone.

Double refraction: Exhibits birefringence, splitting light into two rays, contributing to its sparkle and fire.

Cleavage: Poor, meaning it's less prone to breaking along specific planes.

Fracture: Conchoidal, similar to a shell, with smooth curved surfaces.

Density: 3.50-3.80 g/cm³, heavier than many other gemstones.

Pleochroism: Shows slight color variation depending on viewing angle, adding depth and complexity to its appearance.

Chemical Composition: Tsavorite a variety of grossular garnet. Its chemical formula is Ca₃Al₂(SiO₄)₃.

Tsavorite Formation

Metamorphic Furnace: Tsavorite formation begins during high-grade metamorphism, where intense heat (500-700°C) and pressure (5-10 kbar) transform pre-existing rocks deep within the Earth's crust. These conditions promote the breakdown of existing minerals and the crystallization of new ones, including tsavorite.

Chemical Orchestration: Calcium-rich rocks like gneisses and marbles provide the structural framework for tsavorite's garnet structure. Trace elements, particularly chromium (Cr) and vanadium (V), play crucial roles in its color. Cr acts as the primary pigmenting agent, imbuing tsavorite with its characteristic green hue. Vanadium can enhance the green color or contribute to yellow tones depending on its concentration.

Graphite's Role: The presence of graphite is often associated with tsavorite deposits. Graphite likely plays a role in reducing conditions, stabilizing Cr and facilitating its incorporation into the garnet lattice, contributing to the deeper green color.

Geodynamic Setting: The majority of tsavorite deposits reside within the Mozambique Orogenic Belt, a zone of ancient metamorphic rocks formed during continental collisions. This belt provided the necessary thermal and pressure regimes for tsavorite formation, particularly along shear zones and contact zones between different rock types.

Tsavorite garnet from Merelani Hills, Tanzania
Photo: pegmatite.ru

Crystallization: Under these conditions, calcium, Cr, V, and other elements dissolve in metamorphic fluids and migrate through fractures within the rocks. As temperature and pressure decrease, these elements precipitate and crystallize, forming tsavorite crystals within the fractures or cavities.

Crystal Size and Quality: The size and quality of tsavorite crystals vary depending on factors like the intensity and duration of metamorphism, the availability of elements, and the presence of impurities. Generally, larger and higher-quality crystals are rarer and more valuable.

Occurrence of Tsavorite

The majority of tsavorite deposits are concentrated within the Mozambique Orogenic Belt, a swathe of ancient metamorphic rocks traversing eastern Africa. This belt provides the necessary geological context and geochemical conditions for tsavorite's crystallization.

Within the Mozambique Orogenic Belt, Kenya and Tanzania host the most significant tsavorite mines. Notable examples include the Merelani area in Tanzania and the Taita-Taveta region in Kenya.

Specific rock units within the belt, such as graphitic gneisses and calcareous marbles, are particularly favorable for tsavorite occurrence. Contact zones between these units can be particularly rich in tsavorite deposits. Additionally, although less common, pegmatites can also host tsavorite crystals.

This rough tsavorite crystal was mined near Merelani, Tanzania

Countries

Kenya: Home to the famed Merelani area, boasting large and high-quality tsavorite crystals.

Tanzania: Another major player, with significant deposits in the Taita-Taveta region and around the Usambara Mountains.

Madagascar: Offers limited tsavorite deposits, often with a slightly yellowish hue.

Tsavorite Jewelry

Versatility: Tsavorite's vibrant green color makes it a versatile gemstone suitable for various jewelry designs. From classic rings and pendants to modern earrings and bracelets, tsavorite can add a touch of sophistication and elegance to any piece.

Investment: Tsavorite is a valuable gemstone, and its price can increase over time due to its rarity and growing demand. This makes it a good investment for those looking for a beautiful and valuable piece of jewelry.

Tsavorite garnet from Merelani Hills, Lelatema Mts, Simanjiro District, Manyara Region, Tanzania
Photo: pegmatite.ru

Tsavorite FAQ

Tsavorite price

Tsavorite can be quite pricey! Its vibrant green colors and rarity contribute to its high cost, often ranging from $500 to $8,000 per carat.

Tsavorite can range from moderately priced to extremely expensive. Lower quality stones (smaller, less vibrant color, inclusions) can be found for around $500 per carat, while fine quality stones with excellent color, clarity, and cut can reach $8,000 per carat or more.

Why is tsavorite very expensive?

Tsavorite's high cost can be attributed to several factors, primarily its limited availability and exceptional gem qualities. Found in only a handful of mines in East Africa, often under challenging extraction conditions, its scarcity naturally drives up prices. Additionally, large, high-quality tsavorites are exceedingly rare, further intensifying their value compared to smaller stones.

Is tsavorite rarer than emerald?

Tsavorite is generally considered rarer than emerald. Based on the limited geological distribution, specific formation requirements, lower production estimates, and higher price per carat, scientific evidence strongly suggests that tsavorites are indeed rarer than emeralds. While emeralds remain a valuable and sought-after gemstone, tsavorites offer a unique combination of vibrant green color, exceptional clarity, and relative rarity, making them a captivating alternative for those seeking a truly special gem.