86 W. M. Foote — Meteoric Iron from Sams Valley, Oregon. 



Mt. Edith, described by the present author in May last,* is sup- 

 plemented by chemical likeness to a degree which is rarely 

 encountered. Indeed, the chemical difference between these 

 two geographically distant falls is far less than is often noted 

 in different portions of the same mass of meteoric iron. Their 

 analyses confirm what has long been known : namely, that 

 chemical composition alone cannot be relied upon to distin- 

 guish two clearly distinct meteorites. An important physical 

 feature which easily differentiates the two irons is the schrei- 

 bersite content. Etched plates of Sams Valley show two or 

 three times as much of this mineral in prominent patches and 

 rods as does Mt. Edith. The two analyses, affording respec- 

 tively 2'10 per cent and 6'1 per cent schreibersite, tend to con- 

 firm this appearance. Moreover, an abundance of straight 

 capillary " Brezina lamellae" of schreibersite, often in parallel 

 groups, characterizes Mt. Edith, while their entire absence is 

 noted in Sams Valley. A minor distinction is to be found in 

 occasional low crystalline ridges on the Sams Valley, due to 

 the kamacite lamellae resisting unequally the attack of terres- 

 trial agencies. Such structural indications are absent on the 

 Mt. Edith. 



In an examination of the analyses of meteoric irons, Dr. O. 

 C. Farrington has already demonstrated that uniformity of 

 composition is accompanied by a similarity in crystalline 

 structure. 



Sams Valley's nearest geographical neighbors among the 

 siderites are Willamette (200 miles north, in Oregon), a medium 

 octahedrite of totally different crystalline aspect, and Oroville 

 (200 miles south, in California), another medium octahedrite. 

 A comparison by Dr. Farrington shows the latter to contain less 

 schreibersite and plessite than Sams Valley. The Oroville lamel- 

 lae are more swollen than those of Sams Valley, whereas there 

 are far more repeating lamellae in Sams Valley. The differ- 

 ences are such that the two falls could probably be distinguished 

 on any etched sections. While there are doubtless other irons 

 which Sams Valley closely resembles physically, it may be 

 unquestionably accepted as a distinct fall. 



Philadelphia, Pa. 



* This Journal, vol. xxxvii, pages 391-8. 



