Natron in the context of Tibesti

Wadi El Natrun (Arabic: وادي النطرون, lit. 'Valley of Natron'; Coptic: Ϣⲓϩⲏⲧ, romanized: Šihēt, lit. 'measure of the hearts') is a depression in northern Egypt that is located 23 m (75 ft) below sea level and 38 m (125 ft) below the Nile River level. The valley contains several alkaline lakes, natron-rich salt deposits, salt marshes and freshwater marshes.

In Christian literature it is usually known as Scetis (Σκήτις in Hellenistic Greek) or Skete (Σκήτη, plural Σκήτες in ecclesiastical Greek). It is one of the three early Christian monastic centers located in the Nitrian Desert of the northwestern Nile Delta. The other two monastic centers are Nitria and Kellia. Scetis, now called Wadi El Natrun, is best known today because its ancient monasteries remain in use, unlike Nitria and Kellia which have only archaeological remains. The desertified valley around Scetis in particular may be called the Desert of Scetis.

Natrolite is a tectosilicate mineral species belonging to the zeolite group. It is a hydrated sodium and aluminium silicate with the formula Na₂Al₂Si₃O₁₀·2H₂O. The type locality is Hohentwiel, Hegau, Germany.

It was named natrolite by Martin Heinrich Klaproth in 1803. The name is derived from natron (νατρών), the Greek word for soda, in reference to the sodium content, and lithos (λίθος), meaning stone. Needle stone or needle-zeolite are other informal names, alluding to the common acicular habit of the crystals, which are often very slender and are aggregated in divergent tufts. The crystals are frequently epitaxial overgrowths of natrolite, mesolite, and gonnardite in various orders.

The Tibesti Mountains are a mountain range in the central Sahara, primarily located in the extreme north of Chad, with a small portion located in southern Libya. The highest peak in the range, Emi Koussi, lies to the south at a height of 3,415 meters (11,204 ft) and is the highest point in both Chad and the Sahara. Bikku Bitti, the highest peak in Libya, is located in the north of the range. The central third of the Tibesti is of volcanic origin and consists of five volcanoes topped by large depressions: Emi Koussi, Tarso Toon, Tarso Voon, Tarso Yega and Toussidé. Major lava flows have formed vast plateaus that overlie Paleozoic sandstone. The volcanic activity was the result of a continental hotspot that arose during the Oligocene and continued in some places until the Holocene, creating fumaroles, hot springs, mud pools and deposits of natron and sulfur. Erosion has shaped volcanic spires and carved an extensive network of canyons through which run rivers subject to highly irregular flows that are rapidly lost to the desert sands.

Tibesti, which means "place where the mountain people live", is the domain of the Toubou people. The Toubou live mainly along the wadis, on rare oases where palm trees and limited grains grow. They harness the water that collects in gueltas, the supply of which is highly variable from year-to-year and decade-to-decade. The plateaus are used to graze livestock in the winter and harvest grain in the summer. Temperatures are high, although the altitude ensures that the range is cooler than the surrounding desert. The Toubou, who were settled in the range by the 5th century BC, adapted to these conditions and turned the range into a large natural fortress. They arrived in several waves, taking refuge in times of conflict and dispersing in times of prosperity, although not without intense internal hostility at times.

Wadi El Natrun (Arabic: وادي النطرون, lit. 'Valley of Natron'; Coptic: Ϣⲓϩⲏⲧ, romanized: Šihēt, lit. 'measure of the heart') is a depression in northern Egypt that is located 23 m (75 ft) below sea level and 38 m (125 ft) below the Nile River level. The valley contains several alkaline lakes, natron-rich salt deposits, salt marshes and freshwater marshes.

In Christian literature it is usually known as Scetis (Σκήτις in Hellenistic Greek) or Skete (Σκήτη, plural Σκήτες in ecclesiastical Greek). It is one of the three early Christian monastic centers located in the Nitrian Desert of the northwestern Nile Delta. The other two monastic centers are Nitria and Kellia. Scetis, now called Wadi El Natrun, is best known today because its ancient monasteries remain in use, unlike Nitria and Kellia which have only archaeological remains. The desertified valley around Scetis in particular may be called the Desert of Scetis.