- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of Geology Exclusive of North America, Geological Society of America, Boulder, CO, United States
Supplementing previously reported information on the source of material used in jade axes from sites in the British Isles (Prehist. Soc., Pr. v. 29, p. 133-172, 1964), two possible sources in Brittany (France) have been suggested by J. Cogne and P. R. Giot. These are the glaucophane rocks of the Ile de Groix and the eclogites of the Bouvron area north of Nantes. It is possible that the original source of the jadeite has not yet been traced.