No. 2383! THE TROUP, TEXAS, METEORITE— UDDEN. 473 



clear that the impingement of the air currents producing the pits 

 was not the same on the two posterior faces of the meteor as that on 

 the anterior faces. Toward the narrow end the pitting appears on 

 only two of the four flat sides of the stone and is markedly smaller 

 than at the anterior end. The sizes of the pits on different parts of 

 the stone are shown in averages in the following table: 



Table shotting diameters of pits in millimeters on different parts of the surface of the meteor. 



On the two anterior sides 

 On the two posterior sides 



Shortest. 



<» 



Longest. 



12 



4 I 7 



Farthest back on the posterior sides 2 4 



The stone is covered by a brownish black crust measuring from 

 about 0. 1 to 0.3 millimeters in thickness. Magnified under a good hand 

 lens the surface of this crust is seen to have numerous small rugosities 

 presenting quite sharp angles. At various points particles of metallic 

 iron barely protrude through the crust. At some widely scattered 

 places are some oval spots where the exterior of the crust is very 

 smooth and almost shiny. These smooth areas resemble in form, 

 size, and distribution some stony chondri that are seen to be scat- 

 tered through the meteorite when a polished surface of its interior is 

 examined. In some of the chondri the crystalline texture is lami- 

 nated, and this texture evidently shows through the thin crust in 

 some of the smooth areas seen. 



A fracture, or vein, is seen following one of the four sides of the 

 " wedge " at a distance of 3 to 5 millimeters from one of its faces. (See 

 pi. 101.) The course of this vein is sinuous. The vein itself is mostly 

 less than a tenth of a millimeter in thickness and apparently in this 

 stone, as in others of its kind, consists of material like that of the 

 outer fused crust. On the posterior side of the block showing in the 

 photograph there appear three veins running in the same direction 

 near the middle of the section. One of these is evidently the vein 

 seen in the photograph. All three veins no doubt cross the stone 

 obliquely. 



The mineral composition and the petrographic characters of this 

 stone must await the attention of the specialists. 2 Meanwhile a brief 

 mention of its most obvious features may be recorded. Its color is 

 gray when freshly laid bare. When exposed to moisture, this soon 

 gives way to a gray speckled with rusty dots, which become espe- 

 cially conspicuous on a polished surface. Its texture is fine grained. 

 It is chondritic, showing small light grains of an oval outline on a 

 polished surface. These measure mostly less than a millimeter in 



» See p. 477 following. 



