Emerald mining district, Red Sea Governorate, Egypti

Regional Level Types
Emerald mining district	Group of Mines
Red Sea Governorate	Governorate
Egypt	Country

Ancient emerald mines (2000 B.C. - 1200 A.D.). Rediscovered in the fall of 1817 by French adventurer F. Cailliaud. Egypt was the source of almost all emeralds in ancient times. Found in and at the contact of pegmatitic quartz veins traversing mica and talc schists. Thousands of open pits and underground workings.

Detailed microstructural and chemical analyses of the Egyptian emeralds and their host rocks show that three generations of beryl can be distinguished: a colourless pegmatitic beryl; a pale green Cr-poor beryl crystallized from pegmatite-related hydrothermal fluids; and a deep green Cr- and Mg-rich emerald. The crystallization of the Cr- and Mg-rich emerald was controlled by the very local availability of Cr, Mg and Be-rich metamorphic fluids during the Pan-African tectono-thermal event. Emerald-rich quartz lenses demonstrate that those fluids locally did mobilize quartz, too. The pale green emeralds found within the pegmatites in association with colourless beryl are the product of a mobilization of colourless pegmatitic beryl and/or phenakite by late pegmatitic fluids slightly enriched in Cr by an interaction with the Cr-rich country rocks. The late pegmatitic fluids are typically Na-rich as is demonstrated by the pervasive albitization of the pegmatites (Grundmann & Morteani, 2008).

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References