Contrary to popular belief, _granite_ (crystalline igneous rock composed principally of quartz and feldspar) forms only a part of the Teton Range. The Grand Teton (fig. 6) and most surrounding subsidiary peaks are sculptured from an irregular mass of granite exposed continuously along the backbone of the range from Buck Mountain northward toward upper Leigh Canyon. The rock is commonly fine grained, white or light-gray, and is largely composed of crystals of gray quartz and white feldspar about the size and texture of the grains in very coarse lump sugar. Flakes of black or dark-brown mica (biotite) and silvery white mica (_muscovite_) about the size of grains of pepper are scattered through the rock. From the floor of Jackson Hole the granite cliffs and buttresses of the high peaks appear nearly white in contrast to the more somber grays and browns of surrounding gneisses and schists. These dark rocks are laced by a network of irregular light-colored granite dikes ranging in thickness from fractions of an inch to tens of feet (fig. 23). [Illustration: Figure 22. _Indian bowls carved from soapstone, probably from the Teton Range. Mouth of the unbroken bowl is about 4 inches in diameter._] The largest masses of granite contain abundant unoriented angular blocks and slabs of the older gneisses. These inclusions range from a few inches in diameter (fig. 24) to slabs hundreds of feet thick and thousands of feet long. Dikes or irregular intrusions of pegmatite are found in almost every exposure of granite. _Pegmatite_ contains the same minerals as granite but the individual mineral crystals are several inches or even as much as a foot in diameter. Some pegmatites contain silvery plates or tabular crystals of muscovite mica as much as 6 inches across that can be split into transparent sheets with a pocket knife. Others have dark-brown biotite mica in crystals about the size and shape of the blade of a table knife. A few pegmatites contain scattered red-brown crystals of garnet ranging in size from that of a BB shot to a small marble; a few in Garnet Canyon and Glacier Gulch are larger than baseballs (fig. 25). The garnets are fractured and many are partly altered to _chlorite_ (a dull-green micaceous mineral) so they are of no value as gems. Figure 23. _Dikes of granite and pegmatite._ [Illustration: A. _Network of light-colored granite dikes on the northeast face of the West Horn on Mt. Moran. The dikes cut through gneiss in which the layers slant steeply downward to the left. The face is about 700 feet high. Snowfield in the foreground is at the edge of the Falling Ice Glacier._] [Illustration: B. _Irregular dike of granite and pegmatite cutting through dark layered gneisses near Wilderness Falls in Waterfalls Canyon. The cliff face is about 80 feet high. Contacts of the dike are sharp and angular and cut across the layers in the enclosing gneiss._]