293 



A short time after A. von Lasaulx published the results of his 

 microscopic examination. Though at first sight the rock showed great 

 similarity with a basalt rich in glass-basis in which numerous grains 

 of quartz, microcline, and plagioclase were shut up in a groundmass, 

 consisting of brown glass, numerous grains of magnetite, little Intli- 

 shaped crystals of plagioclase, besides yellowish green gi-ains of 

 augite, he regarded it as an artificial product that was accidentally 

 found at the very place where the fire-ball had been seen. He did 

 not exclude however the possibility that it was a melting-product 

 brought about by a flash of lightning, but he denied the possibility 

 that it was a meteorite^). In a report about van Wiik's treatise 

 Emil Cohen likcAvise deemed the meteoric nature exceedingly doubt- 

 ful'). Afterwards he asserted even that the stone of Igast was 

 doubtless a pseudo-meteorite^). 



In J884 the rock was again desci'ibed by Stanislas Meuniek. He 

 acknowledged (hat it was quite different from all known meteorites, 

 and pointed out its resemblance with volcanic rocks, viz. the "ponces 

 quartzifères". Consequently the rock was classed with the "méiéorites 

 volcaniques" by the name of 'igastite" ''). 



H. Michel treated this subject most elaborately, he published a 

 short time ago a description in which he entered into all details, 

 he overlooked however the microscopic investigations of all his 

 predecessors*). The optical character of all the constituents of the 

 rock were defined more exactly, but for the rest the results of his 

 examination agree with those of the former investigators. At last 

 he says : 



"Wenn man welter die ganzlich unmeteorischeOberflache desStückes, 

 "seine scldackige Beschaffenheit, das Fehlen der fur alle Meteoriten 

 "so bezeichnenden thermomorphen Erscheinungen, das Vorkommen 

 "von groben (^uarzkörneraggregaten nebeii Bestandteilen, die sonst 

 "basisclien Gesteinstypen anzugehören pflegen, in Betracht zieht, koramt 

 "man wohl zu der Uberzeugung, dass es sicli wahrscheinlich um 

 "eine bei irgendeinem Glashütten- oder Ziegelbrennerprozess zufiillig 

 "entstandene Schlacke handelt." 



After what has been said before, we may no longer doubt, that 



Ï) Ueber die Vermehrung dei' MetGoritcnsanimlung ties mincralogischen Mtiseums. 

 Sitzungsber. Niederrhein. Ges. f Natur- und Heilkunde. Bonn 1882, p.p. 108 — 110. 



~') Neues Jahrb. f Min. 1883, I, p. 384. 



3) Meteoritenkunde 1. Stuttgart 1894, p 215. 



•*) Meteorites. Paris 1884, p.p. 298—294, 352 (Edm. Frémv, Encyclopédie chi- 

 mique II. 2). 



5) Zur Tektitfrage. Ann. k.k. Naturhist. Hofmuseum. 27. Wieu 1913, p. 6 - 8. 



