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It is, however, well-known, that in several places, obsidian has flowed in streams like lava; for instance, at Teneriffe, at the Lipari Islands, and at Iceland. In an analysis by Vauquelin of a specimen of obsidian from Hecla, which probably flowed as lava, the proportion of silica is nearly the same as in the nodular or concretionary obsidian from Mexico.
They held in their mouths leaden bullets and pebbles of obsidian, which they chewed with a desperate fierceness. It was some time after sunrise when we arrived at the mountain foot. To our consternation no water could be found! The mountains were a range of dry rocks, so parched-like and barren that even the creosote bush could not find nourishment along their sides.
The laminae, to sum up their characteristics, are either quite straight, or slightly tortuous, or convoluted; they are all parallel to each other, and to the intercalating strata of obsidian; they are generally of extreme thinness; they consist either of an apparently homogeneous, compact rock, striped with different shades of grey and brown colours, or of crystalline feldspathic layers in a more or less perfect state of purity, and of different thicknesses, with distinct crystals of glassy feldspar placed lengthways, or of very thin layers chiefly composed of minute crystals of quartz and augite, or composed of black and red specks of an augitic mineral and of an oxide of iron, either not crystallised or imperfectly so.
Both pyramids are nearly covered with a coating of debris, full of bits of obsidian arrows and knives, and broken pottery. On the teocalli of the moon we found a number of recent sea-shells, which mystified us extremely; and the only explanation we could give of their presence there was that they might have been brought up as offerings.
Humboldt, also, has described little cavities, which he compares to the tails of comets, behind sphaerulites in laminated obsidian rocks from Mexico, and Mr. Scrope has described other cavities behind fragments embedded in his laminated trachyte, and which he supposes to have been produced during the movement of the mass.
And near the northern extremity of the isle, a third group of mammelated heights could be recognised under the general name of Perboewatan, from which issued several obsidian lava-flows, with a steep slope; these dated back perhaps to the period of the first known eruption of 1680.
When we got to Obsidian Mountain, Miss Hayes and I decided that we would like to go up a little distance and get a few specimens to carry home with us. Our camp for the night was supposed to be only one mile farther on, and the enlisted men and two wagons were back of us, so we thought we could safely stay there by ourselves.
Be this as it may, an inspection of any good collection of such articles shows the much higher finish of the obsidian implements than of those of flint, agate, and rock-crystal.
I fancy it must have been the crater of a volcano, for I kicked against pieces of obsidian and slag. The volcanic glass broke up with edges as sharp as a razor." "But how far was it to the lake?" asked Carey. "Ah, that I can't tell you in miles. In time it was two hours and a half hard walking. Coming back, one hour and a half. I was away just about four hours."
The disappointment was so keen, that for a few moments I was speechless, and offered no opposition to Tom, who began to grope about with both hands to bring up dozens more pieces of the micaceous rock, and then a piece of flint that seemed to have been chipped into shape, and then a long obsidian blade. "We're a-coming to something after all, Mas'r Harry," said Tom.
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