| In a previous note on “Americanites” (Martin, 1934) from Colombia and Peru, the writer came to the conclusion, on the basis solely of published data, that it was very likely that these so-called tectites are in reality obsidian of terrestrial origin. He stated, however, that “before it is possible to separate the americanites definitely from the tectites, a detailed field examination is required and also a minute determination of the chemical composition of the americanites and of the indubitable volcanic rocks from the neighbourhood.” A generous contribution from the Molengraaff-Fonds enabled the writer in the summer of 1934 to make a special study of tectites, in the course of which he visited the Mineralogical Institute at Jena, (Germany, where he had... |
