METEOKITES OF NORTH AMERICA. 219 



Its dimensions are 8 by 8 indies across the face and 7 inches through, in the thicker part, but with an average 

 thickness of 4 to 5 inches. The back side, as the view is taken, is nearly flat and pretty uniformly covered with cir- 

 cular pittings. On this side, it presents the ordinay appearance of most masses of meteoric iron, the surface crust 

 having entirely disappeared. It seems probable that it lay with this surface in contact with the ground during the 

 three years after it was dug up, and the crust disappeared by the ordinary process of weathering. The front side is 

 less regular in shape and shows several large depressions. This surface is largely covered with the fused crust, which 

 is heaped up in ridges and shows all the perfections of the lines of flow characteristic of irons which have been picked 

 up immediately after their fall; the only change being a partial oxidation of this film so that it appears in places brown 

 instead of black. This character of the St. Croix meteorite, independent of the confirmatory evidence afforded by the 

 circumstances of its history, would make it probable that its fall did not precede by many months the date of its 

 discovery. 



A careful analysis of the iron was made by the writer and his assistant, Mr. Charles G. Allmendinger, with the 

 following results: 



Fe Ni Co P S C Cu Sn 



89. 78 7. 655 1. 325 0. 512 0. 562 traces traces traces =99. 834. 



Specific gravity: First, 7.601; second (on two different pieces), 7.703. 



It contained nodules of troilite, three appearing in one section, from 3 mm. to 12 mm. in diameter. No other 

 inclosures were detected by me. 



I am indebted to Mr. George F. Kunz for sections cut from the mass and polished for etching, and I leave to him the 

 description of the Widrnannstatten figures, etc. The meteorite now forms a part of the collection of Yale University 

 at New Haven. 



Note bt Mb. George F. Kunz. 



■When dilute nitric acid is applied to the St. Croix County iron, the Widrnannstatten figures quickly appear, but 

 unlike the Glorieta and Staunton meteorites, it could not be etched to any depth, because on long continued appli- 

 cation of the acid, the entire surface of the iron rapidly dissolves away, leaving only projecting points of taenite. 

 Hence it was found impossible, as had been at first intended, to reproduce the figures directly from an electrotype 

 taken from the iron. The figures are cubical rather than octahedral in arrangement and more closely approach the 

 Jewellite group of Meunier, particularly the Dickson County iron. In form the entire arrangement resembles the 

 Schwetzite, Werchne-Udinsk, Siberia group, but the figures are about one-third their diameter. It also resemble, 

 somewhat the Trenton, Wisconsin, iron, but still differs from all of those. Troilite is present in nodules 5 to 10 mm. 

 in diameter and also filling the irregular fissures some 50 mm. long and 1 to 3 mm. wide. 



In 1893, Brezina 2 made of Hammond a subspecies of octahedrite, to which he gave the 

 name Hammondite, and which ''instead of the tsenite border around the kamacite lamellae, 

 has fine granular particles of a plainly carbonaceous substance which turns black by etching, 

 arranged in curvilinear plates." In 1895, he described 3 the structure more in detail as follows: 



Laniellse long, somewhat irregularly oriented, 0.35 mm. wide, bunched and much bent, much less prominent than 

 the fields. Band iron (if one can speak of such here) bright gray, slightly dotted and bordered with dustlike granules, 

 apparently belonging to a carbon compound, which turn dark gray by etching and which are arranged in rows. The 

 fields are filled with half shaded combs or with an iron which is more dotted and therefore darker in color than the kama 

 cite. In several places isolated swathing kamacite is found, 2.4 cm. long and 1 mm. broad, surrounded with a dust, 

 like sheath consisting of brightly glistening grains of schreibersite in combination with troilite-schreibersite concre- 

 tions 1 cm. in size. The bands bear many granular inclusions resembling cohenite. Along the natural surface there 

 is an alteration zone from 1 to 2 mm. in width. 



Klein 5 described the meteorite thus : 



It shows pretty streak inclusions in pipe-form. The iron is intersected with bands of dull and compact iron, 

 which contain glistening iron with cohenite inclusions. This dull variety of iron radiates from an inclusion in a six- 

 fold form, and each branch contains in its center a dark layer (cohenite), surrounded and penetrated with bright iron. 



Cohen 4 - 7 described the structure as follows: 



Observed with the naked eye an etched section shows great similarity to an octahedrite. Small, elongated par- 

 ticles of light gray, glistening nickel-iron, which intersect one another nearly at right angles and resemble band iron, 

 are found. A duller, somewhat darker nickel-iron fills up the gaps and appears, therefore, similar to the plessite. 

 Small dark-gray seams which surround the latter (nickel-iron?) may upon cursory examination be regarded as the 

 representative of tfenite, from which, however, it is sharply distinguished by the fact that it envelopes not the band- 

 like, but the fieldlike portions. Dark-gray, rounded, short, staff-shaped, or elongated particles of exactly the same 

 appearance as that of the above seams occur also inside the light-gray nickel-iron, dividing the latter into small strips. 



By closer examination under strong magnification, or, still better, in reflected light under the microscope, it 

 appears that the nickel-iron as a whole is composed of grains, which in the brighter parts are somewhat coarser than in 

 the darker, and that the above distinguished parts are in nowise separated from one another as in the case of the 

 " Trias " in octahedrites. 



