“Clastic rocks are of two general types, those deposited in solution from water and those deposited from mechanical suspension. Flint, chert, etc., are examples of the former; sandstone, limestone, etc., are instances of the latter. The aborigine rarely used this type of rock for axes. The metamorphic rocks are made from the two preceding types by heat and pressure. They have certain structural features, as a rule, such as cleavage and fissility. There is a banded arrangement of the material not due to deposition but to dynamic action; hence arises the familiar banded structure of such metamorphic rocks as gneiss and schist. This type of rock was used by early man for axes to some extent. Nine tenths of the axes in a given collection are made of igneous rocks, and the great bulk of the igneous rocks used are the fine textured rocks, especially basalt and diabase. No rock is better suited for pecking and polishing than the finer grained igneous rocks, nor on the whole are any more resistant to fracture, none are tougher. These are qualities of prime importance in axes. The very fact that so large a percentage of axes are made of the best obtainable material is significant of the fact that early man deliberately sought for certain qualities and looked until he found them. “It shows how truly he was a judge of rock composition and texture, of the suitableness of any given rock for a given purpose. Let us consider in more detail some of the features which he sought, or those which he rejected. In selecting a rock for axe purposes, other things being equal, he would take first of all a quartzless type. If it were a question between granite, which contains quartz, and syenite, which has little, he would almost invariably select the latter. You very rarely see an axe made of quartz-bearing rock in this region. The axe-maker was aware apparently of the hardness of the mineral, of the difficulty with which it was worked, and he naturally avoided rocks that contained it in abundance when seeking axe material. He recognized the mineral, because in rocks which have such similarities as syenite and granite he chose the former, that is, he did not depend upon color or texture alone to guide him, but he must have looked for that glassy mineral that we call quartz. [Illustration: FIG. 257. _(S. about 1–4.)_ _Grooved stone axes of various types. Localities: Missouri, Illinois, Kentucky. F. P. Graves’s collection, Doe Run, Missouri._ ] [Illustration: FIG. 258. (S. 1–2.), from the Phillips Academy collection, indicates the infinite variety of axes. These may be classed under “A,” “B,” and “C,” and yet each possesses an individuality of its own. Particular attention is called to the two lower specimens, which are beautiful examples of axes in stone. ] [Illustration: