Smithsonian Contributions to Knowledge
Format: Paperback
ISBN13: 9781153155984
Paperback|9781153155984
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Overview
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1867 edition. Excerpt: ...of these, rising on the beach and bubbling strongly, has a temperature of 75 C.; and in another rising in a cold stream, but protected by wooden tubbing, I found 70. The water of these springs has a slight odor of sulphuretted hydrogen. June 1st. Soon after leaving Shkabe we passed an outcrop of quartziferous porphyry, showing columnar structure, and remarkable for its richness in double pyram id crystals of pellucid quartz associated with white felspar in a compact gray paste. The volcanic conglomerate-breccia was the prevailing rock, but in places the bluff was formed of an apparently younger deposit of sandy clay. The beach was in many places covered with a layer of magnetic iron sand, from the disintegrated volcanic rocks, well concentrated by the action of the surf. From Shkabe eastward many fragments of vein quartz were seen on the beach. At the mouth of the Kakumi creek we left the sea-shore, and following the wild valley rode a few miles inland to the mines of Kakumi. Here the hills are formed of greenish and gray argillaceous rocks in places brecciated, in others metamorphosed to an euritic rock. These are traversed by dykes of a peculiar white porphyry. This porphyry has a compact paste, generally very white, sometimes gray or greenish, yielding fire with difficulty with the steel. In this are scattered grains, and especially double pyramid crystals, of quartz, which form from a few per cent, to one-third the volume. In rare instances it contains crystals of a white triclinic felspar. Mica and hornblende are never present and rarely chlorite. It contains almost always small cubes of iron pyrites. In weathering it changes to a white kaolin-like substance often discolored by the oxidation of the pyrites. It occurs in dykes, and...
| ISBN-13 | 9781153155984 |
|---|---|
| ISBN-10 | 1153155982 |
| Weight | 0.84 Pounds |
| Dimensions | 9.00 x 6.00 x 0.58 In |
| List Price | $24.86 |
| Format | Paperback |
|---|---|
| Pages | 256 pages |
| Publisher | |
| Published On | 2010-01-01 |
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