Explore gem islands in the Red Sea

The Red Sea island of Zabargad is made of peridotite, a coarse-grained igneous rock filled with beautiful blue peridot gemstones .

Zabargad Island is located about 50 km off the southern coast of Egypt in the Gulf of Foul in the Red Sea. With an area of ​​1.74 km2 ^, this is the largest island in the archipelago in this bay, according to IFL Science . Zabargad is also known as a desert island because it contains very little fresh water and is almost devoid of life, except for a few breeding seabirds and ospreys. What the island lacks in biodiversity, it makes up for in geology.

Zabargad Island lies above the center of tectonic activity. (Photo: Khoroshunova Olga).

During ancient times, people collected peridot gemstones from the island and used them as jewelry for the kings who ruled over the Mediterranean kingdoms. Some of the earliest evidence of mining on the island of Zabargad comes from Egypt more than 3,500 years ago.

The Greeks called the island "Topazios" because they believed it was the source of the gemstone topaz. But scientists identified the rock type at the island's surface as peridotite , a coarse-grained igneous rock rich in olivine and pyroxene . Inside the peridotite layer, the mineral olivine can form the brilliant yellow-green gemstone called peridot.

This type of rock forms at a depth of more than 150km in the Earth's upper mantle. Buried in the hot mantle and subjected to extreme pressure, once viscous magma peridotite cooled and hardened, then was pushed to the surface. Peridotite rose to the Earth's surface due to deep geological faults that occurred tens of millions of years ago, mainly in the early Cretaceous period. Collision of tectonic plates resulted in part of the mantle rising into the crust, forming a strange island made mainly of peridotite.

The island remains above the center of tectonic activity due to its proximity to the Red Sea Narrows , a mid-ocean ridge dividing the African and Arabian plates. The base of the ridge also intersects the East African Rift Valley. Gemstone mining continued on the island into the early 20th century, but almost completely stopped after the Egyptian government nationalized the country's mines in 1958.