Zabargad Island ( arz, جزيرة الزبرجد ', also known as St. John's Island in English) is the largest of a group of islands in

Foul Bay Foul Bay (, "uncleaned bay"; ) is a bay on the Egyptian side of the Red Sea, in the Red Sea Governorate. Geography Foul Bay is located slightly north of the Tropic of Cancer. The town which lies at the most inland section of the bay is Berenice ( ...

Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Mediter ...

. It covers an area of . It is not a

quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...

volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...

island, but rather is believed to be an upthrusted part of

upper mantle The upper mantle of Earth is a very thick layer of rock inside the planet, which begins just beneath the crust (at about under the oceans and about under the continents) and ends at the top of the lower mantle at . Temperatures range from appro ...

material. The nearest island is known as " Rocky Island". The island is slightly north of the

Tropic of Cancer The Tropic of Cancer, which is also referred to as the Northern Tropic, is the most northerly circle of latitude on Earth at which the Sun can be directly overhead. This occurs on the June solstice, when the Northern Hemisphere is tilted toward ...

, and its highest point is .

History

Before the mid 270s CE
Ptolemaic Ptolemaic is the adjective formed from the name Ptolemy, and may refer to: Pertaining to the Ptolemaic dynasty * Ptolemaic dynasty, the Macedonian Greek dynasty that ruled Egypt founded in 305 BC by Ptolemy I Soter * Ptolemaic Kingdom Pertaining ...
activity along the African coast of the Red Sea had been limited with few significant results other than the discovery of the 'topaz' deposits on the island of Gazirat Zabarjad southeast of
Ras Banas Ras Banas ( el, Lepte Akra, script=Latn arz, راس بناس ) is a peninsula in Egypt extending into the Red Sea. The inlet of water sheltered to the south of it is called Foul Bay, at the head of which sits the ancient port of Berenice. It is ...
. ... 2.
Pliny Pliny may refer to: People * Pliny the Elder (23–79 CE), ancient Roman nobleman, scientist, historian, and author of ''Naturalis Historia'' (''Pliny's Natural History'') * Pliny the Younger (died 113), ancient Roman statesman, orator, w ...
, ''HN'' 37, 108 refers to a large topaz that was brought back to Egypt as a gift for
Ptolemy I Ptolemy I Soter (; gr, Πτολεμαῖος Σωτήρ, ''Ptolemaîos Sōtḗr'' "Ptolemy the Savior"; c. 367 BC – January 282 BC) was a Macedonian Greek general, historian and companion of Alexander the Great from the Kingdom of Macedon ...
's queen
Berenice I Berenice I ( grc-gre, Βερενίκη; c. 340 BC – between 279 and 268 BC) was Queen of Egypt by marriage to Ptolemy I Soter. She became the second queen, after Eurydice, of the Ptolemaic dynasty of Egypt. Life Family Berenice was originally f ...
.

Geology

The island is considered

geologically Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Eart ...

unique as it is uplifted mantle, a fragment of the sub-

Red Sea The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; T ...

lithosphere A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust (geology), crust and the portion of the upper mantle (geology), mantle that behaves elastically on time sca ...

. Rocks on the island are mainly lower crustal

igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main The three types of rocks, rock types, the others being Sedimentary rock, sedimentary and metamorphic rock, metamorphic. Igneous rock ...

s. The island became present above sea level after

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

n and

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

tic continental plates converged to cause rocks in the lower crust to be uplifted. The island contains three masses of

peridotite Peridotite ( ) is a dense, coarse-grained igneous rock consisting mostly of the silicate minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica. It is high in magnesium (Mg2+), reflecting the high prop ...

, which are rich in the gemstone peridot (olivine). The island is believed to be the first discovered source of peridot, which was called ''topazios'' in ancient times, hence the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

name for the island, ''Topazios''. Layers of

spinel Spinel () is the magnesium/aluminium member of the larger spinel group of minerals. It has the formula in the cubic crystal system. Its name comes from the Latin word , which means ''spine'' in reference to its pointed crystals. Properties S ...

lherzolite Lherzolite is a type of ultramafic igneous rock. It is a coarse-grained rock consisting of 40 to 90% olivine along with significant orthopyroxene and lesser amounts of calcic chromium-rich clinopyroxene. Minor minerals include chromium and alu ...

s with

anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achie ...

Al-

diopside Diopside is a monoclinic pyroxene mineral with composition . It forms complete solid solution series with hedenbergite () and augite, and partial solid solutions with orthopyroxene and pigeonite. It forms variably colored, but typically dull ...

pyroxenite Pyroxenite is an ultramafic igneous rock consisting essentially of minerals of the pyroxene group, such as augite, diopside, hypersthene, bronzite or enstatite. Pyroxenites are classified into clinopyroxenites, orthopyroxenites, and the websteri ...

s and

hydrous In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...

Cr-diopside pyroxenites can be found too on the island. Pliny, XXXV, chap. 22 says that, according to

Juba Juba () is the capital and largest city of South Sudan. The city is situated on the White Nile and also serves as the capital of the Central Equatoria State. It is the world's newest capital city to be elevated as such, and had a populatio ...

, the island "Topazus in the Red Sea", also had mines producing sandarach (

realgar Realgar ( ), also known as "ruby sulphur" or "ruby of arsenic", is an arsenic sulfide mineral with the chemical formula α-. It is a soft, sectile mineral occurring in monoclinic crystals, or in granular, compact, or powdery form, often in assoc ...

) and ochre, "but neither of them are imported to us from that place."''The Natural History by Pliny the Elder''. Vol. VI. Translated by John Bostock and H. T. Riley. Henry G. Bohn, York St., Covent Garden, London, pp. 239-240 and n. 34.

Nature

The island is part of the

Elba National Park Gabal Elba ( ar, جَبَل علْبَة ' , ), or Elba Mountain, is a peak and, in general, includes the associated mountainous area in the Halaib Triangle of Northeast Africa. Despite being claimed by both Egypt and Sudan, the area is currently ...

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.

Birds

The island serves as a breeding ground for at least nine known species of birds. The most recent discovery was that of 150 pairs of

sooty falcon The sooty falcon (''Falco concolor'') is a medium-sized falcon breeding from northeastern Africa to the southern Persian Gulf region. The word sooty means to be covered in soot (ash), and is used to describe the color of the Sooty Falcon. Hence, ...

(''Falco concolor'') in October, 1994.

Plantlife

There is very little vegetation on the island due to the lack of soil.

Corals and sealife

The

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...

s 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 Diving most often refers to: * Diving (sport), the sport of jumping into deep water * Underwater diving, human activity underwater for recreational or occupational purposes Diving or Dive may also refer to: Sports * Dive (American football), a ...

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: *

Rays Ray may refer to: Fish * Ray (fish), any cartilaginous fish of the superorder Batoidea * Ray (fish fin anatomy), a bony or horny spine on a fin Science and mathematics * Ray (geometry), half of a line proceeding from an initial point * Ray (gra ...

Moray eel Moray eels, or Muraenidae (), are a family of eels whose members are found worldwide. There are approximately 200 species in 15 genera which are almost exclusively marine, but several species are regularly seen in brackish water, and a few are f ...

s *

Octopus An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttle ...

* Crocodilefish *

Cuttlefish Cuttlefish or cuttles are marine molluscs of the order Sepiida. They belong to the class Cephalopoda which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone, which is used for control of ...

Tourism

The island is near

coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. Co ...

s, which are 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 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.

References

External links

St. John's Island peridot information and history
at

Mindat.org Mindat.org is a non-commercial online database, claiming to be the largest mineral database and mineralogy, mineralogical reference website on the Internet. It is used by professional mineralogists, geologists, and amateur mineral collecting, mi ...

Bird Life Information
{{Authority control Islands of Egypt Islands of the Red Sea Red Sea Governorate