Peridot, the vibrant yellowish-green to greenish-yellow gem variety of the mineral olivine, stands as one of the three official birthstones for the month of August. It is a gemstone renowned not only for its singular color but also for its extraordinary origins, which include formation deep within the Earth's mantle and extraterrestrial delivery via meteorites. Historically, peridot has often been mistaken for other precious gems, including emerald and topaz, adding a layer of mystery to its identity. This article explores the multifaceted nature of peridot, delving into its geological formation, global sources, distinctive gemological properties, and the rich tapestry of history and symbolism that surrounds it.
The journey of peridot through human history is as compelling as its geological story. From ancient Egyptian mines to the rugged landscapes of Arizona and the high-altitude deposits of Pakistan, this gem has been prized for millennia. Its allure lies in its unique chemical composition, which dictates its color without the need for impurities, and its durability, which, while suitable for many jewelry applications, requires mindful care. As we examine the characteristics that define peridot, we will uncover the scientific principles behind its beauty and the cultural beliefs that have elevated it to a position of significance in the world of gemstones.
History and Lore
The historical narrative of peridot is deep and often entwined with confusion regarding its true identity. For centuries, this August birthstone was mistaken for other green gems. The most famous example involves the 200-carat gems adorning the Shrine of the Three Holy Kings in Germany’s Cologne Cathedral. These stones were long believed to be emeralds, but were later identified as peridot. Some historians even speculate that Cleopatra’s famed collection of emeralds may have, in fact, been composed of peridot. This confusion was not limited to emeralds; the Red Sea island of Topazios, a name that gave rise to the gemstone topaz, was actually a source of peridot, further complicating its historical record.
The etymology of the name "peridot" is traced to the Arabic word faridat, which simply means "gem." This August birthstone was highly valued in numerous ancient and medieval cultures. It appeared in the jewelry of priests as early as the second century BCE and was later incorporated into the chalices and ecclesiastical adornments of medieval Europe. Beyond its ornamental use, peridot was believed to possess protective qualities. It was used for centuries as a talisman, thought to shield its owner from evil spirits and the "terrors of the night."
The primary historical source for peridot was the Egyptian island of Zabargad (formerly known as Topazios) in the Red Sea. This location is the oldest recorded source of the gem, with mining activities estimated to have begun around 340–279 BCE. The island's environment was so harsh that it earned ominous names such as the "Island of Death" and Ophiodes ("snake island"). Despite these conditions, the peridot produced there has been prized for centuries and remains highly desirable today. The earliest recorded production of peridot dates to approximately 70 A.D. from St. John's Island, also in the Red Sea. Later, significant deposits of fine-quality peridot were discovered in Myanmar (formerly Burma), particularly in the mountainous region of Kyaukpon near Mogok.
In the Middle Ages, peridots were worn with the belief that they could provide foresight and inspiration. The Romans utilized the stones as a defense against enchantment. The gem's connection to cosmic events was highlighted in 2005 when peridot was discovered in comet dust returned by the Stardust space probe, confirming its extraterrestrial origins. In modern times, peridot is recognized not only as the birthstone for August but also as the gemstone given to celebrate a 16th wedding anniversary.
Geological Formation and Sources
Peridot’s formation process is unique among gemstones. As the yellowish-green to greenish yellow gem variety of the mineral olivine, it is created under extreme conditions. Most of the peridot seen in jewelry today originates from the Earth's mantle. It is brought to the surface by volcanic activity, often found within hardened lava that carried it from deep within the Earth. This gemstone can also be found in pallasite meteorites, which are composed of nickel-iron and olivine, having traveled from outer space. While thousands of meteorites have struck the Earth containing olivine, only a select few contain gem-quality peridot.
The chemical composition of peridot is a magnesium-iron silicate, with the formula (Mg,Fe)₂SiO₄. The ratio of magnesium to iron in the crystal is highly variable. Crystals are often flattened and are typically found in granular masses or as embedded grains within finer-grained basic igneous rocks such as basalt or gabbro.
Global sources for this August birthstone are diverse and geologically significant:
- Egypt (Zabargad Island): The oldest and most historically significant source, producing peridot since antiquity.
- Myanmar (Burma): Known for producing some of the finest-quality peridot with deep color and superb transparency, found in the crevices of Kyaukpon mountain.
- United States (Arizona): The main domestic source, specifically from the San Carlos Apache Indian Reservation. The peridot here is a result of massive volcanic eruptions thousands of years ago. Some Apache families have been mining these deposits for decades.
- Modern Sources: Contemporary jewelry peridot primarily comes from China, Myanmar, Pakistan, Tanzania, Vietnam, and the United States.
- Exotic Locations: Peridot can also be found in unique settings, such as Peridot Beach in Hawaii, where the sands shimmer with a luminous green color due to the presence of the gem.
Competition for the title of the world's largest producer has intensified, with China and Pakistan challenging the United States' historical dominance. The value of U.S. peridot production in 1993 was estimated at approximately $1.5 million.
Gemological Properties
Understanding the physical and optical characteristics of peridot is essential for gemologists and enthusiasts alike. Its properties dictate its durability, appearance, and care requirements.
Color and Appearance: Peridot is best known for its distinct lime-green color. Unlike many other gemstones that derive their color from trace impurities, peridot’s hue is an intrinsic part of its chemical composition. The color is determined by the presence of iron and magnesium. Specifically, ferrous iron (FeO) is responsible for the green color, while ferric iron (Fe₂O₃) contributes to more yellow shades. While peridot is one of the few gemstones that occurs in a single color family, it can vary in shade from yellow-green and olive to brown-green. A unique characteristic of peridot is that it maintains its shining color even under artificial light, earning it the nickname "Evening Emerald." It is considered both a day stone and a night stone.
Hardness and Durability: On the Mohs scale of hardness, peridot rates between 6.5 and 7. This makes it softer than many other popular gemstones, such as sapphire or diamond. Consequently, it cannot withstand hard wear and is not recommended for daily use in rings, which are subject to frequent impact. Its distinct cleavage (breakage along preferred planes) and conchoidal (shell-like) fracture also influence its durability and must be considered during cutting and setting.
Crystallography and Physical Characteristics: Peridot crystallizes in the orthorhombic system, meaning it has three crystallographic axes that are perpendicular to one another but all of different lengths. It is a fairly dense gem, with a specific gravity ranging from 3.27 to 3.37.
The following table summarizes key gemological data for peridot:
| Property | Description/Value |
|---|---|
| Mineral Species | Olivine |
| Chemical Formula | (Mg,Fe)₂SiO₄ |
| Crystal System | Orthorhombic |
| Hardness (Mohs) | 6.5 - 7.0 |
| Specific Gravity | 3.27 - 3.37 |
| Refractive Index | Not explicitly stated in sources |
| Primary Color | Yellowish-green to greenish-yellow |
| Luster | Vitreous (glass-like) - inferred from properties |
Note: The refractive index is a standard gemological property, but its specific value for peridot was not provided in the available source materials.
Symbolism and Metaphysical Beliefs
Across cultures and eras, peridot has been imbued with a wide range of symbolic meanings and metaphysical beliefs. Its protective qualities are among its most enduring attributes. Ancient civilizations believed the stone could shield the wearer from evil spirits and negative forces. The Romans specifically used it to guard against enchantment.
During the Middle Ages, peridot was associated with mental clarity and insight, believed to provide foresight and inspiration to those who wore it. In more recent interpretations, peridot is said to carry the healing powers of nature, bringing the wearer success, peace, and good luck. Its vibrant green color, which does not fade in artificial light, reinforces its association with vitality and positive energy, day and night. The discovery of peridot in comet dust has added a modern, cosmic dimension to its symbolism, linking it to the far reaches of the universe.
Care and Cleaning
Due to its gemological properties, peridot requires specific care to maintain its beauty and integrity. With a hardness of 6.5 to 7 on the Mohs scale, it is softer than many other gemstones and is susceptible to scratching and abrasion.
Handling and Storage: Individuals who wear peridot jewelry daily, particularly in rings, should exercise caution to avoid impacts that could chip or fracture the stone. When storing peridot, it is crucial to keep it separate from harder stones and jewelry pieces to prevent scratching. A soft cloth or a compartmentalized jewelry box is ideal for storage.
Cleaning Instructions: To clean peridot, use a soft-bristle brush and a solution of mild dish soap and warm water. Gently scrub the gemstone and its setting, then rinse thoroughly with warm water and dry with a soft, lint-free cloth. Avoid using harsh chemicals, ultrasonic cleaners, or steam cleaners, as these can potentially damage the stone or its setting. The distinct cleavage of peridot makes it particularly vulnerable to sudden temperature changes and physical shock.
Conclusion
Peridot is a gemstone of remarkable character, defined by its unique genesis, singular color, and rich historical legacy. As one of the three birthstones for August, it offers a compelling alternative to spinel and sardonyx, distinguished by its formation deep within the Earth and its occasional arrival from outer space. Its identity has been obscured by historical confusion with emeralds and topaz, yet its true properties—a magnesium-iron silicate composition, a hardness of 6.5 to 7, and an intrinsic green hue—establish it as a gem with a distinct scientific profile.
From the ancient mines of Zabargad to the modern deposits of Arizona, China, and Pakistan, peridot has been a source of fascination for millennia. Its symbolism, rooted in protection, foresight, and good fortune, continues to resonate with contemporary wearers. While its relative softness necessitates careful handling, its enduring beauty and luminous glow under any light source ensure its place as a cherished gemstone for collectors, jewelers, and those born in the month of August.