Natural Green Obsidian

Green Obsidian – Volcanic glass

Green obsidian is a type of volcanic glass that forms when lava rich in iron and magnesium cools rapidly, preventing the growth of large mineral crystals. This rapid cooling results in the smooth, glassy texture for which obsidian is renowned. The distinct green coloration is attributed to the presence of trace minerals such as chlorite, serpentine, and other mineral inclusions.

Unlike other types of obsidian, the green variety is relatively rare and is primarily found in regions with a history of volcanic activity. These regions include parts of the United States, Mexico, Canada, and South America. The geological conditions necessary for the formation of green obsidian make it a true natural marvel.

Obsidian is mineral-like, but not a true mineral because as a glass it is not crystalline; in addition, its composition is too variable to be classified as a mineral. It is sometimes classified as a mineraloid.

The obsidian in the photo is displayed at Stephen Hui Geological Museum, Hong Kong. Credit: Stephen Hui Geological Museum

Most obsidians have a composition similar to rhyolite and granite. Granites and rhyolites can form from the same magma as obsidian and are often geographically associated with the obsidian. Rarely, volcanic glasses are found with a composition similar to basalt and gabbro.

 

These glassy rocks are named "tachylyte."

Pure obsidian is usually dark in appearance, though the color varies depending on the presence of impurities. This can be caused by tiny microscopic inclusions of other minerals (feldspar, amphibole, biotite, quartz) called microlites (not the mineral). They can be observed under a microscope as thin rectangular, sometimes equant crystals that can sometimes form bands and give obsidian its characteristic colour.

In the case of dark green obsidian the colouration is caused varying amounts of Fe and Mg. The green coloration can also be achieved as some gas bubbles (vescicles) remained in the lava flow during crystallization.

Unique Properties and Visual Appeal

Green Obsidian is renowned for its captivating appearance, with shades ranging from pale green to deep emerald. Its translucent to opaque nature allows light to pass through the gemstone, imparting it with an ethereal glow. This play of light and color makes Green Obsidian a popular choice for jewelry, decorative items, and spiritual practices.

Due to its glassy nature, Green Obsidian lacks the well-defined crystal faces found in traditional gemstones. Instead, it boasts a smooth and sleek surface that can be polished to a brilliant shine. Its distinctive appearance, combined with its unique formation process, sets Green Obsidian apart as a remarkable gemstone with an intriguing backstory.

Green Obsidian from Davis Creek in Northern California, USA

Green obsidian is a valuable gemstone that has been used for centuries for its beauty and its metaphysical properties. It is said to promote clarity, intuition, and protection. Green obsidian is also a popular choice for jewelry and for use in healing and meditation.

Caring for Green Obsidian

To maintain the luster and beauty of Green Obsidian, proper care is essential. As a relatively soft gemstone compared to others on the Mohs scale, it is susceptible to scratches and impacts. To prevent damage, it is advisable to store Green Obsidian separately from harder gemstones and to avoid exposing it to harsh chemicals or extreme temperatures. Cleaning can be done using a mild soap and lukewarm water, followed by gentle drying with a soft cloth.