296 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. XIII. 



The olivine was not far from — 



Fe 2 Si0 4 l 

 3Mg 2 SiOj 



The undecomposed silicate, whose amount is almost equal to that of the olivine, consists of: 



Silica 55. 08 .... 29. 38 



Alumina 4 86 .... 2.27 



Iron protoxide 13. 58 3. 02 



Magnesia 22. 70 9. 08 



Lime 2.85 0.81 



Soda 0.93 0.24. 



Potash trace 



13.15 



100. 00 



The whole is therefore almost exactly a bisilicate. 



The proportionate composition of the silicate (amounting to 83.09 per cent of the meteorite) is as follows: 



Silica 46. 88 



Alumina 2. 40 



Iron protoxide 17. 49 



Magnesia 31. 36 



Lime 1. 41 



99.54 

 It is evident that this result bears not the least resemblance to the data obtained by Shepard. 

 Iowa (Linn County) is a chondrite. 



Brezina 910 classed the meteorite as veined white chondrite, and says: 

 The large mass in Tubingen of 432 grams weight has a crust and is nearer Cia than Cwa. A small fragment of the 

 collection of Kunz is strongly marked with metallic veins, one of which is laid bare as an armor face. 



The meteorite is distributed, Amherst having the largest mass (21 pounds, 6 ounces). 

 This is probably the large stone described by Shepard. 4 



BIBLIOGRAPHY. 



1. 1847: Shepard. Fall of meteoric stones in Iowa. Amer. Journ. Sci., 2d ser., vol. 4, pp. 288-289. 



2. 1847: Iowa meteorite (from a letter from Joshua Barney, U. S. Agent, Dubuque, to J. J. Abert, Col. Topographical 



Bureau, Washington). Idem., p. 429. 



3. 1848: Shepard. Report on meteorites — 1. Linn County, Iowa. Amer. Journ. Sci., 2d ser., vol. 6, pp. 403-405. 



(Analysis.) 



4. 1851: Shepard. On meteorites — 4. Description of a large stone of the Linn County, Iowa, fall of February 25, 



1842. Amer. Journ. Sci., 2d ser., vol. 11, pp. 38-39. 



5. 1853: Shepard. Notices of meteoric iron near Lion River, Great Namaqualand, South Africa; and of the detec- 



tion of potassium in meteoric iron — 3. Figure of the Iowa meteoric stone, which was seen to fall February 25, 

 1847. Amer. Journ. Sci., 2d ser., vol. 15, pp. 6-7. 



6. 1858-1865: Von Reichenbach. No. 5, p. 480; No. 6, p. 454; No. 9, pp. 161, 168, 178; No. 10, pp. 359, 363; No. 



11, pp. 294, 300; No. 13, p. 369 (fig.), 377; No. 14, p. 396; No. 20, p. 622; No. 25, pp. 321, 322, 324, 607, 615. 



7. 1870: Rammelsbero. Beitrage zur Kenntnis der Meteoriten III. Linn County, Iowa. Mon. Ber. Berlin. 



Akad., 1870, pp. 457-459. (Analysis.) 



8. 1884: Wadsworth. Studies, p. 104. 



9. 1885: Brezina. Wiener Sammlung, pp. 176, 180, and 232. 



10. 1895: Brezina. Wiener Sammlung, p. 244. 



11. 1903: Farrington. Catalogue of the collection of meteorites. Publ. Field Columbian Mus., Geol. ser., vol. 2, p. 



106. 



MARSHALL COUNTY. 



Marshall County, Kentucky. 



Latitude 36° 50' N., longitude 88° 20' W. 



Iron. Medium octahedrite (Om), of Brezina; Caillite (type 18), of Meunier. 



Found ?; described 1860. 



Weight, 6.8 kgs. (15 lbs.). 



This meteorite was described by Smith, 1 as follows : 

 A piece of this meteorite was sent me from Marshall County (Kentucky). I have not yet seen the entire mass, 

 which is said to weigh 15 pounds and to be scaly in structure. It has the usual characteristics of meteoric iron as seen 

 from the analysis: 



Fe Ni Co Cu P 



90. 12 8. 72 . 32 trace 0. 10 =99. 26 



