December is a month with lots going on so I guess that’s why it has three different birthstones 🙂
Let’s start with Blue Zircon
Zircon is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium. Zircon forms in silicate melts with large proportions of high field strength incompatible elements. For example, hafnium is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal system. The natural color of zircon varies between colorless, yellow-golden, red, brown, blue, and green. Colorless specimens that show gem quality are a popular substitute for diamond and are also known as “Matura diamond”.
The name derives from the Persian zargun meaning gold-hued. This word is corrupted into “jargoon”, a term applied to light-colored zircons. The English word “zircon” is derived from “Zirkon,” which is the German adaptation of this word. Yellow, orange, and red zircon is also known as “hyacinth”, from the flower hyacinthus, whose name is of Ancient Greek origin.
Blue Zircon has a hardness of 6 – 7.5 on the Mohs scale
Zircon is the oldest mineral on earth, dating back more than 4.4 billion years. Found in the earth’s crust, it’s common in most sands and sedimentary deposits, as well as metamorphic rocks and crystallized magma.
Due to its chemical makeup, zircon has survived ages of geologic events like erosion and pressure shifts – recording these changes like a time capsule. Zircon contains the radioactive element uranium, which changes the stone’s chemical structure and color over time, giving us important clues about the formation of our planet.
During the Middle Ages, people believed that zircon could induce sound sleep, ward off evil, and bring prosperity and wisdom.
Blue zircon, in particular, was popular during Victorian times, and frequently adorned English estate jewelry from the 1880s. Zircon with a cloudy or smoky appearance was also popular in mourning jewelry.
In the 1920s, heat treatment became a customary practice to enhance the color of zircon gems for jewelry. Zircon has also been used in the decorative ceramics industry.
Today, zircon is considered a grounding stone that increases confidence and compassion. It is said Zircon can bring visions into reality and provide the guidance needed to achieve goals. While zircon is popular among gem collectors for its range of colors, consumers seem most enamored with the blue variety, and otherwise confused about the history and possibility of this expansive gem.
Moving on to Tanzanite
Tanzanite is the blue and violet variety of the mineral zoisite belonging to the epidote group. The gemstone was discovered by Manuel d’Souza in the Mererani Hills of Manyara Region in northern Tanzania in 1967, near the city of Arusha and Mount Kilimanjaro. Tanzanite is only found in Tanzania, in a very small mining area (approximately 7 km long and 2 km wide) near the Mererani Hills.
Tanzanite is noted for its remarkably strong trichroism, appearing alternately blue, violet and burgundy depending on crystal orientation. Tanzanite can also appear differently when viewed under alternate lighting conditions. The blues appear more evident when subjected to fluorescent light and the violet hues can be seen readily when viewed under incandescent illumination. In its rough state tanzanite is usually colored a reddish brown, and much of it requires heat treatment to remove the brownish”veil” and bring out the blue violet of the stone.
Tanzanite has a hardness of 6.5 – 7 on the Mohs scale
The gemstone was given the name’tanzanite’ by Tiffany & Co. after Tanzania, the country in which it was discovered. The scientific name of “blue-violet zoisite” was not thought to be consumer friendly enough by Tiffany’s marketing department, who introduced it to the market in 1968. In 2002, the American Gem trade association chose tanzanite as a December birthstone, the first change to their birthstone list since 1912.
Unlike many well-known gems that have been in use for centuries, tanzanite’s history is relatively modern.
The common story of tanzanite’s discovery tells of Maasai herders who found blue crystals in the Merelani Hills near Arusha, Tanzania while tending livestock in 1967. They notified a prospector named Manuel d’Souza, who promptly registered claims with the government to begin mining.
Initially, d’Souza thought he was mining sapphires, but the crystal was soon identified as a vibrant blue variety of zoisite – a mineral that had been around since the early 1800s.
Tiffany & Co. recognized this blue gem’s potential to rival more expensive sapphire and agreed to become its main distributor. Instead of publicizing “blue zoisite” – which sounded a little too much like “suicide” – Tiffany named the gem tanzanite to highlight its exclusive geographic origin and introduced it with a promotional campaign in1968.
An estimated two million carats of tanzanite was mined before the Tanzanian government nationalized the mines in1971. The government divided the mines into four sections, or blocks, in 1990.
Tanzanite may not have the long history of other gems, but with such limited supplies and rapidly growing popularity, itis highly prized for its rare beauty.
Now, last but not least come Turquoise
Turquoise is an opaque, blue-to-green mineral that is a hydrated phosphate of copper and aluminum. It is rare and valuable in finer grades and has been prized as a gemstone and ornamental stone for thousands of years, owing to its unique hue. In recent times, turquoise has been devalued, like most other opaque gems, by the introduction onto the market of treatments, imitations, and synthetics.
The gemstone has been known by many names. Pliny the Elder referred to the mineral as Callais (from AncientGreek κάλαϊς) and the Aztecs knew it as chalchihuitl.
The word turquoise dates to the 17th century and is derived from the French turquois for “Turkish” because the mineral was first brought to Europe through Turkey, from mines in the historical Khorasan Province of Persia.
The finest of turquoise reaches a maximum hardness on the Mohs scale of just under 6, or slightly more than window glass.
In the Southwestern United States, turquoise is almost invariably associated with the weathering products of copper sulfide deposits in or around potassium-feldspar-bearing porphyritic intrusives. In some occurrences alunite, potassium aluminum sulfate is a prominent secondary mineral. Typically, turquoise mineralization is restricted to a relatively shallow depth of fewer than 20 meters (66 feet), although it does occur along deeper fracture zones where secondary solutions have greater penetration or the depth to the water table is greater.
Turquoise is nearly always cryptocrystalline and massive and assumes no definite external shape. Crystals, even at the microscopic scale, are exceedingly rare. Typically, the form is a vein or fracture filling, nodular, or botryoidal inhabit. Stalactiteforms have been reported. Turquoise may also pseudomorphously replace feldspar, apatite, other minerals, or even fossils. Odontolite is fossil bone or ivory that has been traditionally thought to have been altered by turquoise or similar phosphate minerals such as the iron phosphate vivianite. Intergrowthwith other secondary copper minerals such as chrysocolla are also common.