Rano Raraku and Maunga Toa Toa are isolated tuff cones of about 0.21 Ma. The crater of Rano Raraku contains a freshwater lake. The stratified tuff is composed of sideromelane, slightly altered to palagonite, and somewhat lithified. The tuff contains lithic fragments of older lava flows. The northwest sector of Rano Raraku contains reddish volcanic ash. According to Bandy, "...all of the great images of Easter Island are carved from" the light and porous tuff from Rano Raraku. A carving was abandoned when a large, dense and hard lithic fragment was encountered. However, these lithics became the basis for stone hammers and chisels. The Puna Pau crater contains an extremely porous pumice, from which was carved the Pukao "hats". The Maunga Orito obsidian was used to make the "mataa" spearheads.