Meteorite Collection — Handbook and Catalogue. 13 



Among characters common to all meteorites which distinguish 

 them from bodies of terrestrial origin may be noted, first, the varnish- 

 like crust always found upon their surface. This is the result of heat- 

 ing and fusion of the surface during passage of the mass through the 

 atmosphere. In the meteoric stones it is usually black and contrasts 

 with the gray or brown of their interior (Winnebago Co., 340, Kny- 

 ahinya, 287, Pultusk, 290). Not infrequently, however, it is of the 

 same color as the interior (Kesen, 258, Washington Co., 345, and 

 Phillips Co., 350). It is usually of a dull lustre (Pultusk, 291, Mocs, 

 324), but occasonally shining (Stannern, 226, Knyahinya, 286). In 

 many individuals it differs in appearance on different portions of the 

 stone, being smooth and compact on one part and on another, rough 

 and slag-like. 



Such appearances often indicate the position which the stone 

 assumed during its fall, the portion bearing the smooth crust having 

 been in advance (die Brustseite) while the other portion was at the 

 rear (die Ruckenscite), (Winnebago Co., 340, Mocs, 331). On meteor- 

 ites which are largely metallic, the crust appears as a brown (Grand 

 Rapids, 116) or bluish (Estherville, 175) oxidation of the surface, con- 

 trasting with the nickel- white color of the interior. It is never more 

 than a millimeter in thickness (Forsyth, 241, New Concord, 273) and 

 frequently exists only as a smoking of the surface (Winnebago, Co., 

 34o). 



Other evidences of surface fusion are seen in the rounded metal- 

 lic beads which stand out over the exterior of most stony meteorites. 

 These are produced by metallic grains which offer a greater resist- 

 ance to heat than the non-metallic portions of the stone. Where the 

 metallic grains are quite small, they give the surface a papillated 

 appearance (Trenzano, 268, Bath, 351) but larger grains produce larger 

 protuberances (Washington Co., 347). 



Often there are visible on the crust of a meteorite (Stannern, 

 226) lines of flow, which closely resemble, though on a much reduced 

 scale, the features of a lava stream, and indicate that the surface of the 

 meteorite was in a similar molten condition. 



The rounding of the solid angles and sharp edges observable in 

 most meteoric individuals (Winnebago Co., 340), even metallic ones 

 (Toluca, 12, 21), is likewise evidence of a former plastic condition of 

 the exterior. 



A second common characteristic of meteorites is to be found in 

 the shallow pits which indent their surface. These vary much in 

 size and depth, but usually have an appearance much like thai of an 

 impression made by a thumb upon a piece of soft clay or putty. 



