OBSIDIAN.
This
mineral was familiarly known to the ancients, and its name is said to
be derived from a Roman, who first brought it to Rome from Ethiopia.
Pliny states that the Romans manufactured mirrors and gems from it; the
Mexicans and Peruvians manufactured their knives, razors, and
sword-blades from obsidian, which appears to have served as a complete
substitute for other materials with those nations, who were yet
unacquainted with the use of iron for weapons and utensils of various
kinds. Baron Humboldt says that Cortez mentioned, in his letter to the
Emperor Charles V., having seen razors of obsidian at Tenochittan; and
the above naturalist likewise discovered, on the Sierra de las Nabajaz,
in New Spain, the old shaft that was used for raising the rough
obsidian, with relics of the tools and half-finished utensils.
The
inhabitants of Quito manufactured magnificent mirrors from obsidian,
and those of the Azores and Ascension islands, and Guiana, used
splinters of obsidian as points for their lances, razors, &c.
Specimens
of arrows and other articles, such as octangular wedges, were
presented a few years ago to the New York Lyceum of Natural History,
being relics from the ruins of Palenque. In the collection of Columbia
College are some razors, or sacrificial knives, the gift of the Hon. J.
R. Poinsett.
Obsidian
occurs massive, in roundish or obtuse lumps, balls, and grains; has a
conchoidal fracture; is semi-transparent and translucent on the edges;
it has a strong vitreous, and sometimes even metallic lustre; its
colors are either pure black, grayish, brownish, greenish-black,
yellow, blue, or white, but seldom red; it sometimes displays a
peculiar greenish-yellow shine, when it is called the irides-
