الفهرس 
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Abstract
Siwa Oasis is one of several depressions scattered throughout the western desert of Egypt. It is a tectonically induced depression located in the northern part of the Western Desert and intensively characterized by salt mineralization and Salt pans. Most of the research works have considered the salinity factor in the soil as a danger and hazard that harms agricultural soils and reduces its production of crops. Conversely, this study considers salinity as an economic factor.
The main objectives of this study were: (1) to evaluate the quality of salt for several uses by using chemical analysis of raw & refined salt and defining the phase role controlling the salt precipitations of raw salts. (2) To use various remotely sensed data and GIS technique for mapping and assessing rock salt as a raw material.
The calculated hypothetical salts show that the percentage of halite in samples ranges between 97.82 and 98.50% in raw salt and between 99.48 and 99.52% in refined salt. The quality of refined salt exceeds the Egyptian (98.5% NaCl) and European (99% NaCl) standards. Analysis of heavy metals and trace elements indicated that all the salt samples were found at very low concentrations below the allowable limits. The precipitated minerals identified by XRD are halite, sylvite, gypsum, carnallite, magnesium sulfate hydrate, sodium chlorate, and bischofite. More than 90% of NaCl present in the solution precipitate alone in the first stages. As a result, this study indicated that the type of Siwa salt is a very good quality salt, which needs a very simple refining process to meet and exceed the international standards of edible (food) salt.
To identify and map the rock salt in the study area, salinity index, band combination, band ratio combination, and principal component analysis (PCA) techniques were used. A new OLI band ratio combination b6/b7:b6/b5:b4/b2 as R:G:B is applied successfully for mapping salt rock as red color in the study area. A Supervised classification technique was successfully used for assessing the salt areas in the study area based on field observation and remotely sensed data. The results show that remote sensing data and GIS technique can be effectively used for mapping rock salt and assessment the reserve in Siwa area.