A literature review reveals that conservation studies of volcanic stonework have focused on tuffs that exhibit serious deterioration. Other volcanic rocks used for monuments or sculpture are basalt, scoria, andesite, dacite, rhyolite, and trachyte. Important examples include the statues on Easter Island, the Buddhist shrine of Borobudur in Java, the churches at Göreme in Turkey and Lalibela in Ethiopia, the rock-cut Buddhas of Japan, and the caves of the Deccan plateau in India. The application of consolidants has been the treatment most frequently tested, but little is known about long-term efficacy. Monuments carved in situ present particularly intractable problems.