Corsi Collection of Decorative Stones

view of stone 786

Corsi 786, approx. 145 x 73 x 40 mm, © Oxford University Museum of Natural History

OUMNH Number: 786  
Name and quarry location: Imperial porphyry, porfido bigio, from Gebel Dokhan, Eastern Desert, Egypt  
Geological description: Andesite-dacite porphyry; pink to white phenocrysts of plagioclase feldspar and black euhedral crystals of hornblende in a grey-brown groundmass.  
Comments: Porfido bigio is intermediate between the red imperial porphyry (such as no.783) and the black (such as no.788). Imperial porphyry comes from Gebel Dokhan (the ancient Mons Porphyrites) in the Eastern Desert of Egypt. The imperial quarries were worked from at least the 1st century through to the 5th century AD, using a workforce of slaves. The ancient quarries were rediscovered in 1823, and their location was described by the quarry hunter William Brindley (1887). They were never reopened on a commercial scale, so virtually every example of this stone seen around the world was quarried in ancient Roman times.  
References: Brindley (1887); Corsi (1845) 200-204; Harrell (2010a); Lazzarini (2002c) 233-235; Price (2007) 202-203  
Further information:

Corsi's classification: Class 15. Porphyry; Species 1.; i. Antique porphyry  
Corsi's text: 194.4 Porfido antico. Marmor Porphyrite. Porfirite. Porfido bigio... la prime cave del porfido rosso si aprissero presso l'istmo di Sues. Di altra cave di porfido aperta nella Tebaide... si è chiamata Tebano. Marmo Romano  

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