St. John's Island (also known as Zabargad, Zebirget, Topazios) is the largest of a group of islands in Foul Bay, Red Sea in Southern Egypt. It covers an area of 4.50 square kilometres (approx.). It is not a quaternary volcanic island, but rather is believed to be an upthrusted part of upper mantle material. The nearest island is Rocky Island. The island is slightly north of the Tropic of Cancer, and its highest point is 235 metres.
Contents |
The island is considered geologically unique as it is uplifted mantle, a fragment of the sub-Red Sea lithosphere. Rocks on the island are mainly lower crustal metamorphic rocks. The island became present above sea level after African and Asiatic continental plates converged to cause rocks in the lower crust to be uplifted. The island comprises three massives of peridotite, which are rich in the gemstone peridote (olivine). This gem makes the island notable as it is believed to be the first discovered source of peridot, which was called topazios in ancient times, hence the Greek name for the island, Topazios. Layers of spinel-lherzolites with anhydrous Al-diopside pyroxenites and hydrous Cr-diopside pyroxenites can be found too on the island. The presence of all of these minerals has led to mining on the island which dates back as early as ancient times.
The island is part of the Elba National Park meaning the island is conserved. However, the island was closed to the public for one year due to damage to corals and the disturbance of birds who breed on the island.
The island serves as a breeding ground for at least 9 known species of birds. The most recent discovery was that of 150 pairs of Falco concolor (Sooty Falcon in October, 1994.
Vegetation on St. John's Island is very hard to find. Due to the island's lack of soil and infertile rocks, plants have nowhere to grow.
The corals surround the island and act as a barrier for the fish and other sea life which live among it. However, the corals recently became damaged due to increased tourist activity and the expansion of the diving industry on the island. The coral is located approximately 25 metres below the surface
Fish that can be found within the nearby waters and corals are:
The island is located near coral reefs which serve as a popular diving attraction for tourists. The diving industry on the island has increased as well as the tourism industry on the island in general resulting in the construction of hotels and diving shelves. The beaches are often quiet and are relatively unspoilt by development. However, most tourists go to this island as a "stop-off" before going to Rocky Island in the south.