The term “green amethyst” often causes confusion, as amethyst is known for its purple hue. This green gemstone, commonly known as Prasiolite, is a distinct variety of quartz. Its unique green color prompts examination of its origins, properties, and market differentiation.
The True Identity of Green Amethyst
“Green amethyst” is a trade name for Prasiolite, a green quartz also called vermarine. While a form of quartz like purple amethyst, it possesses a different color due to its specific chemical composition and formation processes. The Federal Trade Commission considers “green amethyst” misleading, as amethyst is defined by its purple color.
Prasiolite forms through two main methods. Natural Prasiolite is rare, occurring when amethyst is exposed to natural heat or radiation deep within the Earth’s crust, such as from volcanic activity. This process transforms purple quartz into its green counterpart. Most Prasiolite on the market is produced by heat-treating purple amethyst or citrine from specific geographic locations, particularly Brazil. This treatment, typically around 500 degrees Celsius, alters iron impurities within the quartz crystal lattice, resulting in the green color. This controlled process simulates natural conditions, making the treated stone widely accepted and stable.
Formation and Characteristics
Prasiolite is chemically silicon dioxide (SiO2). Its green color is attributed to iron impurities within the crystal structure. The exact shade and intensity vary based on iron concentration, geological conditions, or treatment methods. Natural Prasiolite tends to be pale green with yellowish or grayish tones and may have uneven color distribution. Treated Prasiolite often displays a more uniform and vibrant green.
It is generally transparent to translucent. Prasiolite ranks 7 on the Mohs hardness scale, indicating durability and resistance to scratching. This hardness makes it suitable for use in various types of jewelry. Like other quartz varieties, it has a vitreous luster when polished and exhibits a conchoidal fracture. Prasiolite crystallizes in the trigonal system.
Identifying Green Amethyst
Distinguishing Prasiolite from other green gemstones or imitations involves observing its characteristics. Its color typically ranges from pale to medium green, often with a soft, minty hue. Be cautious of stones with overly vibrant or unnatural deep greens, as these might be imitations or heavily treated materials. Prasiolite is transparent to translucent, and genuine pieces often contain natural inclusions or imperfections visible under magnification. Flawless stones may not be natural Prasiolite.
The Mohs hardness of 7 is a useful indicator. This means it can scratch glass and will not be easily scratched by common metals like a steel nail. Compared to other green gemstones, Prasiolite is distinct. Peridot is an olivine mineral with a different crystal structure. Emeralds are generally deeper green, more valuable, and have a slightly higher hardness of 7.5 to 8. Prasiolite specifically refers to green quartz derived from amethyst.
Applications and Maintenance
Prasiolite is a popular choice for jewelry due to its appealing green color and durability. Its Mohs hardness of 7 makes it suitable for various jewelry pieces, including rings, pendants, and earrings. The stone can be cut into numerous shapes and sizes, such as rounds, ovals, and emerald cuts, to enhance its brilliance. Prasiolite offers an affordable alternative to more costly green gemstones like emeralds or tsavorite garnets.
To maintain Prasiolite’s appearance, clean it with lukewarm water and mild soap, gently scrubbing if needed. Dry the stone with a soft cloth. Avoid harsh chemicals, ultrasonic cleaners, or prolonged direct sunlight, as these can cause color fading, especially in heat-treated varieties. Store Prasiolite in a dark jewelry box or bag, away from heat sources.