The eyes were covered with obsidian, calcite, and black hued gemstone possibly onyx. They harvested berries, made baskets, hunted, and made obsidian arrowheads and spears. Saws were at first serrated materials such as flint, obsidian, sea shells and shark teeth. Eight other graves contained grave goods, including beads made of shell, carnelian and obsidian. The priest would then cut through the abdomen with an obsidian or flint blade. There are important deposits of granite, marble, sandstone and obsidian. There is evidence of the exchange of obsidian and flint during the stone age. Its sides are embedded with prismatic blades traditionally made from obsidian. Only two colourways were shown, those being orange peel/obsidian and anthracite/vivid blue. In some areas, remains of obsidian and sandstone workshops have been found. Vitreous silicon dioxide is known as tektites, and obsidian, and rarely as lechatelierite. They were inscribed into wooden tablets about long using shark teeth and obsidian flakes. Tools made from obsidian fragments were used by some of the earliest Mesoamericans. Tipped with obsidian, fish bones, or copper heads. Hunter-gatherers left tools made of obsidian glass dated back to 8000 BC.