Peridot, the vibrant green gemstone designated for the month of August, stands as a testament to the Earth's fiery origins. Unlike many colored gems that derive their hue from trace impurities, peridot's signature olive to lime-green color is an intrinsic property of its chemical composition. This gem, with its rich history intertwined with ancient civilizations and volcanic landscapes, offers a compelling narrative of geological wonder and cultural significance. As one of the few gemstones occurring in a single color family, peridot's unique formation and enduring appeal make it a subject of fascination for gemologists, collectors, and jewelry enthusiasts alike. This article delves into the science, history, and symbolism of peridot, drawing exclusively from the provided source materials to present a comprehensive overview of this remarkable August birthstone.
Historical Lore and the Path to Birthstone Status
The history of peridot is as ancient as the gem itself. Historical records indicate that peridot has been treasured for millennia, with its use dating back to the ancient Egyptian civilization. The gem was particularly favored by the Egyptians, who mined it on the island of Zabargad (also known as St. John's Island) in the Red Sea. This source was the primary supplier of peridot for centuries, and the gem was so highly valued that it was often mistaken for emeralds due to its rich green hue. Historical accounts suggest that the Egyptians wore peridot not only as a symbol of wealth and status but also for its perceived protective properties against evil spirits and nightmares.
The journey of peridot from an ancient talisman to a modern birthstone is a relatively recent development. The concept of assigning specific gemstones to each month of the year has evolved over time, with the most influential modern list being the American National Association of Jewelers' (NAJ) 1912 standardization. This list, which has been largely adopted by the jewelry industry, officially recognized peridot as the birthstone for August. This designation helped solidify peridot's place in contemporary jewelry culture, moving it from a niche historical gem to a widely recognized symbol for those born in the eighth month. The gem's association with the sun is also deeply rooted in history; ancient cultures believed peridot was a gift from the sun, capable of warding off darkness and evil. This solar connection is reflected in its name, which is derived from the Arabic word "faridat," meaning "gem." The historical significance of peridot is thus a blend of its ancient Egyptian origins, its journey through various cultures, and its formal recognition in the 20th century.
Geological Formation and Sources
Peridot's formation process is a direct window into the Earth's internal dynamics. It is a variety of the mineral olivine, specifically the magnesium-rich end-member. Its genesis is unique among gemstones, as it is found primarily in two types of geological environments: volcanic rocks and deep within the Earth's mantle. The most significant source of gem-quality peridot comes from the Earth's upper mantle. Here, under extreme heat and pressure, olivine forms and is brought to the surface through volcanic activity. This process can occur in two ways: either through mid-ocean ridge volcanism, where the mantle material is exposed, or through hotspots and continental rifts that transport mantle-derived magma to the surface. The peridot crystals found in these volcanic rocks, such as basalt, are often small and require careful extraction.
The historical and contemporary sources of peridot are diverse. As mentioned, the ancient Egyptians mined peridot from Zabargad Island in the Red Sea, a source that was exploited for over 3,500 years. This island's peridot deposits are found in peridotite, a rock composed almost entirely of olivine, which is the primary host for the gem. In more modern times, significant peridot deposits have been discovered in other parts of the world. Myanmar (Burma) is a notable source, particularly from the Mogok region, which is renowned for producing high-quality peridot crystals. Pakistan, specifically the Kohistan region, is another major source, with peridot found in basaltic rocks. The United States also has peridot sources, with Arizona being a key location. The San Carlos Apache Indian Reservation in Arizona is a major producer of peridot, where the gem is mined from volcanic formations. Other sources include Australia (Queensland), Brazil, China, Egypt, Kenya, Mexico, and South Africa. The geographic distribution of peridot sources underscores its connection to tectonic and volcanic activity across the globe.
Gemological Properties and Identification
Peridot's gemological properties are distinctive and serve as key identifiers for gemologists. Its most defining characteristic is its color, which ranges from a light, yellowish-green to a deep olive green. The gem's color is not due to trace elements like chromium or vanadium, as is common in many other green gems, but is an intrinsic part of its chemical composition. The green hue is caused by the presence of iron (Fe) within the crystal lattice. The intensity of the color can vary based on the iron content; higher iron levels generally produce a darker, more olive tone, while lower levels result in a lighter, more vibrant green. Peridot is one of the few gemstones that exhibits a relatively narrow color range, making it unique in the colored gemstone market.
In terms of physical properties, peridot has a hardness of 6.5 to 7 on the Mohs scale. This places it in the medium-hardness category, making it durable enough for most jewelry applications but requiring some care to avoid scratches from harder materials like diamonds, sapphires, or rubies. Its cleavage is good but can be a concern during the cutting process; peridot has cleavage in two directions, which can lead to chipping if not handled properly by skilled lapidaries. The gem's refractive index typically ranges from 1.654 to 1.690, and it is singly refractive, meaning light travels at a single speed through the crystal. Peridot has a specific gravity of 3.34 to 3.37, which is relatively high for a non-metallic gem. It is also a pleochroic gem, meaning it can show slight variations in color intensity when viewed from different crystal directions, though this effect is often subtle.
The chemical formula for peridot is (Mg, Fe)₂SiO₄, indicating it is a solid solution between the magnesium-rich forsterite (Mg₂SiO₄) and the iron-rich fayalite (Fe₂SiO₄) end-members. This composition is what gives peridot its characteristic green color and other physical properties. When evaluating peridot for quality, gemologists consider color, clarity, cut, and carat weight. The most valued peridot is a rich, vibrant green without brownish overtones, with high clarity (few inclusions), and is well-cut to maximize its brilliance. Large peridot crystals are relatively common compared to other gemstones, so peridot can be found in larger carat sizes without a prohibitive increase in price.
Symbolism and Metaphysical Beliefs
Beyond its physical properties, peridot is steeped in symbolism and metaphysical beliefs that span centuries and cultures. Historically, it has been associated with light, the sun, and positive energy. The ancient Egyptians believed that peridot was a "gem of the sun" and wore it to ward off evil spirits and protect against nightmares. It was also thought to have healing properties, particularly for the liver, spleen, and digestive system, and was believed to promote restful sleep and peace of mind. These ancient beliefs have persisted into modern times, with contemporary crystal healers attributing various metaphysical properties to peridot. It is often associated with prosperity, growth, and renewal, aligning with its vibrant green color that symbolizes nature and vitality.
In modern crystal healing practices, peridot is believed to be a stone of compassion and forgiveness. It is said to help release past burdens, encourage positive change, and attract abundance and good fortune. Some practitioners associate peridot with the heart chakra, believing it can help heal emotional wounds and foster a sense of emotional balance and well-being. The gem's connection to the sun is also emphasized in modern metaphysics, where it is thought to bring light to dark situations, enhance self-esteem, and promote a cheerful and optimistic outlook on life. While these beliefs are not scientifically proven, they contribute to peridot's enduring cultural appeal and make it a popular choice for jewelry that carries personal significance and intention.
Care and Maintenance
Given its gemological properties, peridot requires specific care to maintain its beauty and durability. With a hardness of 6.5 to 7 on the Mohs scale, it is softer than many other gemstones like diamonds (10), sapphires (9), and rubies (9). Therefore, it is susceptible to scratching if stored or worn alongside harder gems. It is advisable to store peridot jewelry separately in a soft cloth or a lined jewelry box to prevent abrasion. When wearing peridot, it should be removed before engaging in activities that could expose it to harsh impacts or abrasive surfaces, such as gardening, heavy lifting, or sports.
Cleaning peridot is straightforward but requires gentle methods. Warm, soapy water and a soft brush are the recommended cleaning agents. Avoid using ultrasonic cleaners, as the vibrations can potentially damage the stone, especially if it has any inclusions or fractures. Similarly, steam cleaning is not advisable due to the heat and pressure involved. After cleaning, the jewelry should be rinsed thoroughly with clean water and dried with a soft, lint-free cloth. It is also important to avoid exposing peridot to sudden temperature changes, as this can cause thermal shock and potentially damage the gem. By following these simple care guidelines, owners can ensure that their peridot jewelry remains vibrant and beautiful for generations.
Conclusion
Peridot stands as a unique and captivating gemstone, distinguished by its intrinsic green color, volcanic origins, and rich historical legacy. From its ancient Egyptian roots as a sun gem to its modern status as the August birthstone, peridot has maintained its allure across millennia. Its formation deep within the Earth and its journey to the surface through volcanic activity make it a geological marvel, while its gemological properties—such as its hardness, color, and chemical composition—provide a scientific foundation for its identification and appreciation. The symbolism and metaphysical beliefs associated with peridot, though not scientifically validated, add a layer of cultural depth that enhances its appeal. Finally, with proper care, peridot jewelry can be a lasting treasure, embodying the vibrant energy of the sun and the enduring beauty of the natural world. For those born in August, peridot is more than a birthstone; it is a connection to the Earth's fiery heart and a symbol of light, growth, and renewal.