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I remember having seen similar balls filling a vein in transition-slate, near the castle of Schauenstein in the margravate of Bayreuth. The feldspar approximates sometimes to vitreous feldspar when disseminated in very thin laminae in a mass of granular diabasis, decomposed, and emitting a strong argillaceous smell.
A compact crystalline rock, banded in straight lines with innumerable layers of white and grey shades of colour, varying in width from the thirtieth to the two-hundredth of an inch; these layers seem to be composed chiefly of feldspar, and they contain numerous perfect crystals of glassy feldspar, which are placed lengthways; they are also thickly studded with microscopically minute, amorphous, black specks, which are placed in rows, either standing separately, or more frequently united, two or three or several together, into black lines, thinner than a hair.
These beds include subordinate layers of greenish impure clay, soft micaceous and calcareous sandstones, and reddish friable earthy matter with white specks like decomposed crystals of feldspar; they include, also, hard concretions, fragments of shells, lignite, and silicified wood.
Hence, from the southern part of Tres Montes to the northern end of Chiloe, a distance of 300 miles, we have closely allied rocks with their folia striking on an average in the same direction, namely between N. 11 degrees and 22 degrees W. Again, at Valdivia, we meet with the same mica-schist, exhibiting nearly the same mineralogical passages as in the Chonos Archipelago, often, however, becoming more ferruginous, and containing so much feldspar as to pass into gneiss.
DIORITE, still less siliceous, is composed of hornblende and feldspar, the latter mineral being of different variety from the feldspar of granite and syenite. GABBRO, a typical basic rock, corresponds to basalt in chemical composition.
TALC SCHIST consists of quartz and TALC, a light-colored magnesian mineral of greasy feel, and so soft that it can be scratched with the thumb nail. HORNBLENDE SCHIST, resulting in many cases from the foliation of basic igneous rocks, is made of folia of hornblende alternating with bands of quartz and feldspar. Hornblende schist is common over large areas in the Lake Superior region.
The second dike is more remarkable; it is slightly tortuous, about eighteen inches thick, and can be traced for a considerable distance along the beach; it is of a purplish-red or brown colour, and is formed chiefly of ROUNDED grains of quartz, with broken crystals of earthy feldspar, scales of black mica, and minute fragments of claystone porphyry, all firmly united together in a hard sparing base.
Talcose Granite, or Protogine of the French, is a mixture of feldspar, quartz, and talc. It abounds in the Alps, and in some parts of Cornwall, producing by its decomposition the kaolin or china clay, more than 12,000 tons of which are annually exported from that country for the potteries. The former of these is an aggregate of schorl, or tourmaline, and quartz.
The hair of the men is worn loose; tufts of green and yellow feathers flutter over the forehead, while around their necks and dangling over their naked chests are seen strings of porcupine quills, shell beads, turquoises, bright pebbles, feldspar, apatite, anything in short that glitters and shines. Bunches of similar material glisten in their ears.
The basalt is generally black and fine-grained, but sometimes grey and laminated; it contains some olivine, and high up the valley much glassy feldspar, where, also, it is often amygdaloidal; it is never highly vesicular, except on the sides of rents and on the upper and lower, spherically laminated surfaces.
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