Corsi Collection of Decorative Stones

view of stone 984

Corsi 984, approx. 145 x 73 x 40 mm, © Oxford University Museum of Natural History

OUMNH Number: 984  
Name and quarry location: Porfido delle Alpi, from the Alps  
Geological description: Quartz porphyry. Greyish brown colour. Prominent white subhedral feldspar phenocrysts, some showing compositional zoning with lamellar-twinned interiors and untwined rims. Rounded glassy quartz phenocrysts and prismatic dark brown ferromagnesian mineral, probably amphibole. All set in very fine-grained pale brown groundmass. Similar in mineralogy to 0983, but with different proportions of feldspar and quartz phenocrysts.  
Comments: This locality has not been confirmed.  
Further information:

Corsi's classification: Class 15. Porphyry; Species 1.; ii. Italian porphyries  
Corsi's text: 196.10/ S26.2 Altro dello stesso luogo [Porfido delle Alpi]  

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