A group of Microcline crystals from Pike’s Peak, Colo.
Labradorite, showing multiple twinning (the striation), and the iridescent play of colors
Plate 36
Crystal form of a pyroxene; a and b prism faces, m the beveled edge between two prism faces
Cross section of a pyroxene crystal showing the lines of intersection of the two cleavage planes
Cross sections of pyroxenes, showing typical forms taken by crystals