Stone tools were formed by chipping flint, jasper, or other forms of quartz, such as chalcedony, into flakes with sharp edges. This was done by striking the nodule of stone a sharp blow with another stone held in the hand or mounted in a handle of hide or wood to form a stone hammer. The flakes were then shaped by pressing the edges with a horn point--say, part of a deer antler--to force a chip from the flake. The chipping tool was sometimes fitted with a hide or wood handle set at right angles to the tool, so that its head could be hit with a stone or horn hammer. The flake being worked upon, if small, was often held in the hand, which was protected from the slipping of a chipping tool by a pad of rawhide. Heat was not used in chipping, and some Indians took care to keep the flake damp while working it, occasionally burying the flake for a while in moist soil. The cutting edge of a stone tool could be ground by abrasion on a hard piece of granite or on sandstone, but the final degree of sharpness depended upon the qualities of the stone being used as a tool. Slate could be used in tools in spite of its brittleness. In general, stone tools were unsuitable for chopping or whittling wood. [Illustration: Figure 9 Stone hammer Stone wedge Stone knife with rawhide thong handle] Splitting was done by starting the split at the upper, or small end, of a balk of timber with a maul and a stone wedge or the blade of a stone axe, hatchet, or knife. The stone knives used for this work were not finished tools with wood handles, but rather, as the blade was often damaged in use, selected flakes fitted with hide pads that served as a handle. The tool was usually driven into the wood with blows from a wooden club or maul, the brittle stone tool being protected from damage by a pad of rawhide secured to the top, or head, of the tool. Once the split was started, it could be continued by driving more wedges, or pointed sticks, into the split; this process was continued until the whole balk was divided. White cedar was split into quarters by this method and then the heartwood was split away, the latter being used for canoe structural members. From short balks of the length of the longest rib or perhaps a little more, were split battens equal in thickness to two ribs and in width also equal to two, so that by splitting one batten two ways four finished ribs were produced. The broad faces of the ribs were as nearly parallel to the bark side of the wood as possible, as the ribs would bend satisfactorily toward or away from the bark side only. Black spruce, however, was split in line with the wood rays, from the heart outward toward the bark, so that one of the rib's narrow edges faced the bark side; only in this direction would the wood split readily and only when made this way would the ribs bend without great breakage. [Illustration: Figure 10 Wooden mauls (2, 3 used to set ribs with 4, 5) Driving sticks]