Laying   Peacock tail    
The “peacock tail” or “fan” pattern is also a common solution, though the characteristic feature of this pattern makes it suitable only in specific contexts.
ventaglio policentrico

For further info please refer to:

manuale porfido
manuale posa

Two books are available at Consorzio Cavatori Produttori Porfido (Italian and English)
info@porfido.net