The quarries in the vicinity of Yedi Tașlar on Çigri Dâg in the Troad were an important source of grey granite in the Roman period. The distinctive granite from these quarries has a violet hue and is often referred to as granito violetto. The quarries are no longer worked today and as a result are well-preserved. A large number of roughed-out column shafts are still preserved in them. More
Ponti, G. (1995). 'Marmor Troadense: granite quarries in the Troad: a preliminary survey', Studia Troica 5: 291–320.