Note 23 — Chapter VII · CENTRAL CHILE:—STRUCTURE OF THE CORDILLERA. (continued 2)

This rock is quite black, and fuses into a black bead, attracted strongly by the magnet; it breaks with a conchoidal fracture; the included crystals of augite are distinguishable by the naked eye, but are not perfect enough to be measured: there are many minute acicular crystals of glassy feldspar.