Showing papers in "American Mineralogist in 1948"

Optical properties of glass from Alamogordo, New Mexico

Abstract: Specimens of glass resulting from the explosion of the experimental atomic bomb at Alamogordo, New Mexico, have, by various means' come into the hands of numerous institutions and collectors. Notwithstanding this availability, no studies of the material have been published, although a mere description of its physical character would have no bearing on atomic problems. Samples of the glass were collected by C..A. Anderson of the Geological Survey with the permission of Major General Leslie R. Groves, Commanding General for the Manhattan District. The results of a brief study of this glass, made in the laboratories of the U. S. Geological Survey, will no doubt be of interest to mineralogists and petrologists. The glass, in general, formed alayer 1 to 2 centimeters thick, with the upper surface marked by a very thin sprinkling of dust which fell upon it while it was still molten. At the bottom is a thicker fiIm of partly fused material, which grades into the soil from which it was derived. The color of the glass is a pale bottle green, and the material is extremely vesicular' with the size of the bubbles ranging to nearly the full thickness of the specimen. Figure 1 shows photomicrographs of typical specimens of the

Tincalconite Crystals from Searles Lake, San Bernardino County, California

Abstract: This appeared in a section of the Bulletin headed \"Extraits de diverses publications.\" Literature references are given for most of the extracts, all of which are concerned with new mineral names, but no reference si given with the extract on tincalconite which is quoted in full above. No trace has been found of any original publication by Shepard2 on this material and it seems that such may never have been accomplished. Mineralogists generally3 considered the name tincalconite to apply to a variety of borax rather than to a distinct mineral. After half a century it was pointed out by Schallera that \"it is obvious\" that Shepard's tincalconite \"was the S-hydrate of the borax series, NazO 2BzOt.5HzO identical in composition with 'octahedral borax'.\" According to Schaller it is \"not very abundant but rather widespread, coating both borax and kernite.\" It forms from borax, the 10 hydrate of the series, by partial dehydration or from kernite, the 4 hydrate, by hydration. So far it has been found only in powdery form. Natural borax crystals such as are found embedded in the muds of Borax Lake in Lake County and Searles Lake in San Bernardino County, California, and numerous other localities are probably partly or wholly altered to the S-hydrate and so should be considered pseudomorphs of tincalconite after borax. It is very easy to observe the process of partial

The Use of Becke line colors in refractive index determination

Abstract: The dispersion of immersion liquids is generally much greater than that of most minerals of the same refractive index. Colors appear in the Becke line when the liquid and mineral dispersion curves intersect. The colors produced oder a guide to the wave length for which the liquid and mineral have the same refractive index. Frcm the Becke line colors the refractive index of the mineral for the D (589 mμ) line can be estimated with accuracy better than ±.002.