 | | Journal (article/letter/editorial) | | -28 6 J U N E 29, 1915 OBSIDIAN FROM HRAFNTINNUHRYGGUR, ICELAND: ITS LITH OPH YSiE AND SURFACE MARKINGS................................... 255 The Hrafntinnuhryggur obsidian....................................13, 2016 25(5 F. E. WRIGHT----OBSIDIAN FROM ICELAND in accord, as to the genesis of the lithophysae...Cliff, with their contents of prismatic quartz, tridymite, adular-like and tabular soda-orthocla.se, magnetite...February 13, 2016 258 F. E. WRIGHT----OBSIDIAN FROM ICELAND T h e H r a f n t in n u h r y g g u r O b s |  | | Journal (article/letter/editorial) | | image showing outline of tabular quartz after tridymite crystals that line the thunder-egg cavity wall;the...a layer of prismatic crystals of quartz after tridymite, which in turn are covered by a thin veneer of...mineral is actually a quartz pseudomorph after tridymite. The observed biaxial character could result from...from incomplete replacement in some crystals; tridymite can be metastable at ordinary temperatures (Deer...Howie, and Zussman 1963), and the inversion of tridymite from a hexagonal, uniaxial, high-temperature form |  | | Journal (article/letter/editorial) | | i n , The Meiling Points of Cristobalite and Tridymite. Am. Journ. of Science 4 6 (1 918), S. 417 ff...ff. C. N. F e n n e r , The Relations belween Tridymite and Cristobalite. Trans. Soc. Glass. Techn. 8 (1919)...Tridymit in Lithophysen des Obsidians von Hrafntinnuhryggur (Island) vor. ny wenig höher 1,857, n ^ tiefer |  | | Journal (article/letter/editorial) | | “hot spot” volcanoes in continental areas like Iceland and Yellowstone. No active obsidian-producing rhyolitic...formation of obsidian and perlite is reported from Iceland and California (Kearey et al., 2009). 2. Volcanic...Vecchina, Pietre Cotte obsidian, Italy; Hrafntinnuhryggur, Iceland; the Glassy Mountains, Obsidian Dome...800 1200 1400 -11 -8 2,0x10 6,0x10 954°C Iceland 1207°C -11 -11 4,0x10 8,0x10 -8 1,0x10 -11...tertiary pitchstones are located in Scotland, Iceland and Italy. The oldest preserved volcanic glass |  | | Book (volume) | | Lugert Granophyre. S.E. Nose of Welsh Hill, Northeastern End of the Wichita Mountains, Okla. (H) 44...Texture in Diabase from Beaver Bay, Lake Superior Region, Minn. (1584 U) (J) 46 65. The Same. Nicols...Obsidian ings. Bull. G.S.A., XXVI, from Hrafntinnuhryggur, Iceland; and Rosenbusch-W'iilfing: Mikroskopische...cases Hned with delicate crystals of quartz, tridymite, cristobaUte, feldspar, and fayaHte.^ Von Richthofen...crystal mon periodic resorption in the equatorial region of a columnar by the more strongly than along |
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