H. L. Preston — San Angelo Meteorite. 



271 



general appearance as have all forged meteoric irons we have 

 seen. 



On slicing the mass we find the troilite nodules very scarce, 

 the largest and only prominent one we have come across being 

 26 mm in its greatest diameter and continuing of this size only 

 through three thin slices. The Widmanstatten figures are 

 brought out sharp and distinct on the etched surfaces, and are 

 much more regular both in form and size, than in any 

 other iron with which I am familiar. The rhombic figures 

 are from an inch to an inch and a half in diameter, and vary 

 but little throughout the mass. The so-called Laphamite lines 

 are prominently present, extending across the large patches of 

 plessite. 



There are two exceedingly interesting veins which appear on 

 either end of most of the slices, that are filled with a black, 

 lustrous graphitic-looking mineral ; the longest of these veins 

 following the curve is ll cm and varies from 1 to 4 mm in width ; 

 the other is 6 cm long with a like variation of from 1 to 4 mm in 

 width. 



Another distinguishing feature of this iron are the numerous 

 small fissures or cracks, usually extending from the exterior sur- 

 face inwards, and following in a zigzag course along the edges of 

 the kamacite plates, and in some instances the rhombic form of 



San Angelo meteorite sketch showing fissures; about £ natural size. 



the Widmanstatten figures as seen on the cut showing etched 

 surface, is strongly outlined by these fissures as seen in sketch. 

 These show clearly that with a little more heat the expansion of 

 these cracks or fissures, would have caused masses to separate from 

 the iron, which would tend to cause the large pittings, as sug- 

 gested by me in an article in the January number of this year, 

 of this Journal. In one case, as seen in left-hand edge of cut, 



