Amethyst is the official birthstone for the month of February.
Amethyst is a violet to purple variety of quartz that owes its color to gamma irradiation (Berthelot, 1906) and the presence of traces of iron built into its crystal lattice (Holden, 1925). The irradiation causes the iron Fe(+3) atoms that replace Si in the lattice to lose an electron and form a [FeO4]0 color center (Lehmann and Moore, 1966).
Amethyst's formula is SiO2
Amethyst derives its name from the ancient Greek amethustos, meaning literally "not drunk", as it was believed to guard against drunkenness (see the story on Bacchus below). Traditionally associated with purity and piety.
The color in amethyst from most localities is unevenly distributed in the individual crystals. In amethyst geodes, it is often most intense in the growth zones under the rhombohedral faces (at the tips). Occasionally the color is deeper under either the r or z rhombohedral faces, giving the crystal a pinwheel appearance when viewed from the top. In prismatic crystals, the color may appear in phantom-like thin layers, while in scepters and skeleton quartz the color is often concentrated along the edges, and accompanied by smoky zones. Despite the intense color, the content of iron occupying Si positions in amethyst is rather low, in the 10-100 ppm range (Dennen and Puckett, 1972).
When heated to more than about 300-400°C, amethyst loses its violet color and often turns yellow, orange or brown, and then resembles the quartz variety citrine, but depending on the locality and the temperature during the heat treatment it may also turn colorless or - rarely - green (Rose and Lietz, 1954; Neumann and Schmetzer, 1984).
Amethyst crystals do not get very large, crystals longer than 30cm are very rare.
It is found in various forms and shapes, the most common growth forms are:
1. Druzy crystal aggregates which outline cavities; the crystals are usually short-prismatic and often lack prism faces. Most common in volcanic rocks, but also in hydrothermal veins, and even in cavities in sedimentary rocks;
2. Scepters (late syntaxial overgrowth) on other color varieties of quartz, in particular in high- to medium-temperature environments like alpine-type fissures and pegmatites;
3. Split-growth crystals ("artichoke quartz") in hydrothermal veins in ore deposits, but also in volcanic rocks.
4. As individual well-formed crystals in small cavities and fissures, in particular in volcanic rocks.
5. As hydrothermal vein filling, often with several growth phases with variable color that cause a banding pattern.
Tibetans make and use amethyst prayer beads or malas, as they consider the stone sacred to Buddha – and in biblical lore, Amethyst was among the stones adorning Aaron’s breastplate. It is often used to adorn liturgical items such as pectoral crosses, and its association with compassion, Christ, the angel Adnachiel, and the Apostle Matthias makes it a favorite for use in Catholic clergy rings.
Amethyst is a powerful and protective stone. It guards against psychic attack, transmuting the energy into love and protecting the wearer from all types of harm, including geopathic or electromagnetic stress and ill wishes from others.
One of the most well-known of those protections involves amethyst’s purported power to prevent drunkenness. A myth about Bacchus, the Roman god of wine, has promoted this belief. The story goes as follows:
The Story of Bacchus and Amethyst
"Long ago, a beautiful maiden was on her way to worship at the Temple of Diana. However, she had the misfortune of crossing paths with the god of wine, Bacchus. Angered since he’d just suffered some slight, he’d vowed to take revenge on the next person he met. He spied the maid and unleashed his two guardian tigers upon her. As the great beasts bounded towards the hapless lass, the goddess Diana intervened. To spare her such a terrible fate, she turned her into a pure, clear stone.
Immediately, remorse seized Bacchus. To atone for his actions, he poured his wine over the stone, staining the crystal a deep, violet hue. And so, the maiden Amethyst lent her name to the crystal."
Although presented in a Classical guise, this myth only dates from the Renaissance. The French poet Remy Belleau created this story in 1576 as part of a poem on gemstone beliefs. Nevertheless, the idea that the stone could guard against drunkenness does go back to the Ancient Greeks. Amethystos means “not drunk” in Ancient Greek. They believed you could drink all night and remain sober if you had an amethyst in your mouth or on your person.