E. E. Howell — Beaver Creek Meteorite. 435 



Nickel-iron 17*13 



Magnetite -16 



m .,.. _ .,_ (-15 in magnetic, 4-90 



Troihte 5'0o - v & *• ,.\ 



in non-magnetic part) 



Soluble silicates and phosphate.. 37*23 



Insoluble silicates and chromite. 40-43 



100-00 



Microscopical Discussion • by Dr. Geo. P. Merrill. 



The stone is of a gray color and granular structure, quite 

 fine grained and friable but showing to the unaided eye a 

 finely granular ground mass studded with small spherules or 

 chondri in sizes rarely if ever exceeding 2 mm in greatest diam- 

 eter, and averaging not more than half that amount. With 

 the pocket lens it is seen that the ground mass is also largely 

 chondritic, but interspersed with granular material and glisten- 

 ing metallic particles. So far as material is at hand for com- 

 parison, the stone macroscopically most resembles that of New 

 Concord, Ohio, but is much more granular and friable, as well 

 as more pronouncedly chondritic. In the thin section under 

 the microscope it presents no features not common to stones 

 of its class, and various portions of the field show structures 

 in every way similar to those of the meteorites of Mezo- 

 Madras, Homestead, and Dhurmsala as figured by Tschermak* 

 or that of the San Emigdio stone as described by rn.yself.-f* 

 There are the usual monosomatic and polysomatic chondri 

 sometimes of olivine alone, enstatite alone, or olivine and 

 enstatite together, in granular or porphyrinic forms with glassy 

 base, or radiating and barred forms. The olivines not infre- 

 quently occur with interiors made up of small rounded granules 

 imbedded in a glass base, but extinguishing simultaneous with 

 the outer portion. In many respects the microstructure 

 closely simulates that of the San Emigdio stone, but the ap- 

 parent fragmental nature is less conspicuously marked. In 

 two instances small irregular colorless granules were observed 

 giving faintly the twinning striae and inclined extinctions 

 characteristic of plagioclase feldspars. It is not possible from 

 the examination of the two slides at command to state more 

 definitely as to the presence or absence of this or of silicate 

 minerals other than those mentioned. 



* Die Mikroskopische Beschaffenheit der Meteoriten. etc. Plates vn and vm. 

 f Proc. U. S. National Museum. 



