Zabargad Island in the Red Sea is made up of peridotite, a coarse-grained magma rock rich in beautiful green peridot gemstones.
Zabargad Island is located about 50 km off the southern coast of Egypt in Foul Bay of the Red Sea. Covering an area of 1.74 km2, it is the largest island in the archipelago within this bay, according to IFL Science. Zabargad is also known as a desert island due to its scarcity of fresh water and almost complete lack of life, except for some breeding seabirds and ospreys. Despite the lack of biodiversity, the island compensates with its geological significance.
Zabargad Island is located above an active tectonic center. (Photo: Khoroshunova Olga).
Throughout ancient times, people collected peridot gemstones from the island and used them to create jewelry for kings ruling the Mediterranean kingdoms. Some of the earliest evidence of mining on Zabargad Island dates back to Egypt over 3,500 years ago.
The Greeks referred to the island as “Topazios” because they believed it was a source of topaz gemstones. However, scientists have identified the surface rock of the island as peridotite, a coarse-grained magma rock rich in olivine and pyroxene. Within the peridotite layer, the mineral olivine can form a brilliant yellow-green gemstone known as peridot.
This type of stone forms at depths of over 150 km in the upper mantle of the Earth. Buried in the scorching mantle and subjected to extreme pressure, peridotite was once viscous magma that gradually cooled and solidified, only to be pushed to the surface. Peridotite emerged due to deep geological faulting that occurred tens of millions of years ago, primarily in the early Cretaceous period. The collision of tectonic plates caused a portion of the mantle to rise through the crust, forming this unusual island predominantly made of peridotite.
The island remains above an active tectonic center due to its proximity to the Red Sea Rift, a mid-ocean ridge that divides the African plate and the Arabian plate. The base of this ridge also intersects with the East African Rift Valley. Gemstone mining continued on the island until the early 20th century but nearly ceased entirely after the Egyptian government nationalized domestic mines in 1958.
