Agata del San Gottardo, from San Gottardo - perhaps St Gotthard, Ticino, Switzerland
Geological description:
Chalcedony (cryptocrystalline quartz) - perhaps from a large chert pebble, jaspery towards rim.
Comments:
Labelled in the past variously as ‘S.Gottardo, Switzerland’ and ‘the S. Gottardo Monti Berici Venetia’ [sic], this could be a glacial erratic from the former Alpine locality, but should not be confused with Pietra di San Gottardo, an Oligocene limestone from the Badia and S. Gottardo quarries in the Berici hills around Vicenza.
References:
Further information:
Corsi's classification:
Class 14. Quartz and its varieties; Species 5. Agate