Gemstones of the Great Rift Valley
Tanzania and East Africa is located in one of the most geologically active regions of our planet. For millions of years, intense tectonic activity created some of the world’s most famous landmarks such as the Great Rift Valley, the Kilimanjaro or the Ngorongoro crater. These same forces are what formed the many rare gemstones discovered in the region.
TANZANITE
Tanzanite is a rare variety of Zoisite, found in only one locality in the world and prized for its unique and dramatic color change and pleochroism. This rare gem is naturally trichroic showing blue, red-violet and yellow-green colours on each of its crystal axes.
The most coveted hues in Tanzanite are its royal blue to violet colours, which is rare to find naturally, this is why almost all tanzanites receive a heat treatment to achieve this prized colour.
Tanzanite was formed 585 million years ago in the Merelani hills, the only known source of Tanzanite, located south of Mount Kilimanjaro in Northern Tanzania.
Discovered in 1967, Tanzanite quickly caught the attention of gemmologists and collectors around the world for its rarity and beautiful colour. This new gem was celebrated with great enthusiasm by Tiffany Jewellers of New York, who named the stone after its country of origin as ‘the most beautiful blue stone to be discovered in 2000 years’.
The Tanzanite deposits are found in only 14 square kilometres in the whole planet, and are split into four mining blocks. Since the early 1980’s we’ve worked in partnership with miners in sourcing the finest Tanzanite rough for our lapidary and collection.
- Species: Zoisite
- Color: royal blue, blueish purple to violet
- MOHS hardness scale: 6.5 - 7
- Cristal system: Orthorhombic
- Chemical composition: Ca2AI3/O/OH/SiO4/Si2O7
- Specific gravity: 3.10 - 3.38
- Birth stone/Zodiac: December/Sagittarius
- Energy: transformation, prosperity
CHRYSOPRASE (Chalcedony)
Chrysoprase is the most valuable variety of the chalcedony group of gems. This opaque to translucent gem is known for its apple green to mint green colour which it derives from trace amounts of nickel.
The name Chrysoprase comes from the ancient Greek words for Gold ‘Chryso’ and Leek ‘Prasos’ and describes its characteristic golden green colour. Chrysoprase has been worn since antiquity, where ancient Greeks and Romans would cut Cameos and Intaglios and ancient Egyptians would craft beads.
In more recent times, the deposits of Upper Silesia (Poland) were once the main source of Chrysoprase which was used by European Kings and Queens to adorn their palaces, however the mine has been exhausted since the 14th century. Today the main source for chrysoprase is found in Queensland, Australia and Haneti, Tanzania.
We source our Chrysoprase from our own mine in Haneti, northern Dodoma, capital of Tanzania. The Mantheakis family has been working and promoting Tanzanian Chrysoprase since 1986, allowing the gemstone to be appreciated by many jewellery designers around the world.
- Species: Chalcedony
- Color: green, apple-green
- MOHS hardness scale: 6.5 - 7
- Cristal system: Cryptocrystallin
- Chemical composition: SiO2
- Specific gravity: 2.65 - 2.91
- Birthstone/Zodiac: May/Taurus & Gemini
- Energy: happiness and prosperity
Spessartite (Mandarine garnet)
Spessartite is a member of the Garnet group of gems and is known for its vibrant orange to reddish orange colours. Mandarin Garnet is a variety of Spessartite, found in African localities and famous for its pure orange colour, which combined with its brilliance and hardness makes for a very sought after gem by jewellers and collectors worldwide.
First named after the Spessart Mountains in Bavaria, Germany, where this mineral was found, it remained a very rare find. Spessartite was made famous in 1990 from the discovery of new sources in Namibia and later in Nigeria and Tanzania.
In 2008, important discoveries of Spessartite and mandarin garnets were made in Loliondo, near the Serengeti National Park, in Tanzania, which were characterized by its rich and vibrant orange colour, that local miners called Fanta garnets, due to its resemblance to the popular soda, this rare find placed the small Masai town of Loliondo on the world gemstone stage.
We’ve sourced spessartites from a variety of African localities and have worked directly with artisanal miners from the now famous Loliondo locality in sourcing the finest mandarin garnets since its discovery.
- Species: Garnet
- Color: orange
- MOHS hardness scale: 7.0 – 7.5
- Cristal system: Cubic
- Chemical composition: Mn32+AI2[SiO4]3
- Specific Gravity: 4.09 - 4.15
- Birthstone/Zodiac: January/Capricorn
- Energy: consistency, creativity
Spinel (Mahenge)
Spinel is known for its amazing brilliance, hardness and wide range of spectacular colours, the most valuable ones being fiery red, cobalt blue and hot pink.
For centuries, red Spinel’s were mistaken for Ruby’s; to the extent that many famous rubies in Crown Jewels around the world are actually spinels: the most famous being the Black Prince's ruby, a magnificent 170-carat red spinel that adorns the Imperial State Crown of England in the British Crown Jewels. Spinel was distinguished from ruby in 1783 by mineralogist Jean Baptiste Louis de Rome de Lisle who in the process gave birth to the science of gemology.
Spinels of all colours have been found in many localities around the world, the most famous being red from Myanmar, cobalt blue from Vietnam and hot pink from Tanzania.
Spinels have been found in Tanzania since the early 1980s but were made famous with the discovery in Mahenge of four huge spinel crystals weighing 6 to 54 kg, that turned Tanzania into a major source of spinels in the world. Ever since, the deposit of Mahenge has become synonymous with fine vivid hot pinkish-red spinels, to the extent that the name of this small Tanzanian town is spoken of in all major luxury jewellery houses. We’ve sourced our spinels from our mines: Mahenge and Tunduru and continue to work closely with miners in the Mahenge deposit
- Species: Spinel
- Color: Blue, Purple, Pink, Red
- MOHS hardness scale: 8.0
- Cristal system: Cubic
- Chemical composition: MgAI2O4
- Specific Gravity: 3.57 - 3.70
- Birthstone/Zodiac: August/Leo
- Energy: power & hope
Tsavorite (Grossular Garnet)
Tsavorite is a rare variety of Green Grossular Garnet found only in a few localities across East Africa. This gemstone is known for its rich pure 'jungle' green, yellowish green and bluish green colours which it gets thanks to the presence of trace amounts of chromium and vanadium. Tsavorite is prized for its vibrant colour and strong brilliance, which combined with its rarity makes for one of the most sought-after Gemstones of the century.
Initially discovered in 1967, in northern Tanzania by geologist Campbell Bridges, who made four years later a second discovery across the border in southern Kenya, of the first commercially mined source of Tsavorite. The trade name for this green garnet was given by then president of Tiffany & Co, Henry B. Platt (who also named Tanzanite) together with Bridges in honor of the locality where Tsavorite was made famous from: the famed Tsavo National Park.
Tsavorite is only found in a few localities in East-Africa, mostly in Tanzania, Kenya and to a lesser extent Madagascar. From 1995 to 1999, we were one of the first to mine for Tsavorite in Rungwa south-eastern Tanzania, and today we continue to source our Tsavorite from this locality and from the Lemshuku and Merelani deposits in northern Tanzania, the latter being the famous source of Tanzanite too.
- Species: Garnet
- Color: yellowish to bluish Green
- MOHS hardness scale: 7.0 – 7.5
- Cristal system: Cubic
- Chemical composition: Ca3AI2[SiO4]3
- Specific Gravity: 3.57 - 3.73
- Birthstone/Zodiac: January/Capricorn
- Energy: consistency
Moonstone
Moonstone belongs to the orthoclase feldspar group and is treasured for its distinctive shimmering effect, known as adularescence, which reflects light in different colours creating a visually pleasing effect. The most valuable variety, Blue Moonstone, is known for its colourless body color and blue sheen. Moonstones are also found in a wide variety of colours ranging from white, grey, brown, peach, black and all displaying a unique sheen or shimmer.
Moonstone has been used in jewellery for thousands of years and captivated ancient civilisations since. The Greeks and Romans both associated Moonstone with their lunar deities (Artemis & Diana) believing it was brought to earth from frozen moonlight.
Over the centuries many cultures have cherished the beauty of moonstone and its mystical allure. In more recent times, moonstone has been used by some of the most famous jewellery designers and houses.
Historically the main source for moonstone has been from Myanmar, India and Sri Lanka. Since 2003, a new discovery in Kilosa, Morogoro region, Tanzania has captivated the world with the quality and variety of colours it produces, some unique to Tanzania. We have worked directly with artisanal miners to source our moonstone.
- Species: Feldspar
- Color: White, Grey, Black, Brown, Peach with Sheen
- MOHS hardness scale: 6.0 – 6.5
- Cristal system: monoclinic
- Chemical composition: K[AISi3O8]
- Specific gravity: 2.56 – 2.59
- Birthstone/Zodiac: June/Cancer
- Energy: Intuition, feminine energy, new beginnings
Rose Quartz
Rose Quartz is one of the rarer colored varieties of crystalline Quartz. Cherished for its pure to purplish pink colour, Rose Quartz is often opaque and milky, making transparent stones with a strong saturation of colour more valuable and sought after worldwide.
Rose Quartz jewelry, amulets and decorative objects have been discovered dating back to ancient Mesopotamia around 7000BCE. Known as a “Love Stone” or a “Heart Stone”, Rose Quartz has captivated many civilizations throughout history from the far east to the Mediterranean cultures for it feminine energy and symbolism for beauty and love.
In antiquity, the Greeks and Romans associated this gem with the Goddess of Love and Beauty, Aphrodite ( Venus ) and was worn as a personal seal and as a token of love as early as 600 B.C.
The main sources for Rose Quartz has been Brazil and India known for large specimens used in ornamental and decorative arts. More recently significant deposits of fine quality Rose Quartzs have been discovered in Madagascar, Tanzania and Mozambique.
We source our Rose Quartz directly from artisanal miners in Morogoro and Ruvuma, Regions of Tanzania and from Mozambique.
Since 2015 a new variety of Cherry Quartz has been found near the shores of lake Natron, (which we call Natron Quartz), in reference to the pink alkaline lake and the colour of this variety of Quartz.
- Species: Quartz
- Color: Pink to Purplish-Pink
- MOHS hardness scale: 7.0
- Cristal system: Trigonal
- Chemical composition: SiO2
- Specific gravity: 2.651
- Birthstone/Zodiac: January/Capricorn
- Energy: Love, Beauty, Feminity