METEORITES — HENDERSON AND PERRY 



243 



Hexahedrltes. — Analyses of different meteorites of the liexahedrite 

 type show there is little variation between any two of them (table 1). 

 Hence the chemical evidence indicates that a rather definite alloy 

 is formed which produces rather simple etch patterns consisting of 

 one or more sets of parallel lines. The name kamacite is given to 

 this composition and pattern, and the delicate structural lines are 

 called Neumann lines. A meteorite containing only this relationship 

 of iron and nickel is called a hexahedrite. 



The compositions of hexahedrltes are not absolutely definite. The 

 variations from the average can be seen by comparing the individual 

 index ratios, obtained by dividing the molecular ratio for iron by the 

 sum of the molecular ratios of nickel and cobalt. The average index 

 ratio of analyses given in columns 1 to 15 of table 1 is 16.7, and 

 the average ratio for 6 north Chilean hexahedrites given in column 

 17 is 16.9. Bearing in mind that all these meteorites probably did 

 not form under identical conditions, we see that the amount of 

 variation is relatively small. 



T= trace. 

 Column 1. 



2. 



3. 



4. 



5. 



6. 



7. 



Uwet, Africa. Min. Mag., vol. 17, p. 127, 1914. 



Walker County, Alabama. Meteoritenkunde, vol. 3, p. 173, 1905. 



Iredell, Texas. Amer. Journ. Sci., ser. 4, vol. 8, p. 415, 1899. 



Bruno, Sask., Canada. Amer. Journ. Sci., ser. 5, vol. 31, p. 209, 1936, 



Murphy, North Carolina. Meteoritenkunde, vol. 3, p. 227, 1905. 



Cedartown, Georgia. To be described by S. H. Perry. 



Summit, Alabama. Amer. Journ. Sci., ser. 3, vol. 40, p. 322, 1890. 



Scottsville, Kentucky. Meteoritenkunde, vol. 3, p. 218, 1905. 



Warialda, Australia. Rec. Qeol. Surv., New South Wales, vol. 10, p. 75, 1921. 



Barraba, Australia. Rec. Qeol. Surv., New South Wales, vol. 10, p. 75, 1921. 



Hex River, Africa. Meteoritenkunde, vol. 3, p. 225, 1905. 



Braunau, Bohemia. Meteoritenkunde, vol. 3, p. 207, 1905. 



Holland's Store, Georgia. Meteoritenkunde, vol. 3, p. 240, 1905. 



Cerros del Buei Muerto, Chile. Chemie der Erde, vol. 7, No. 3, p. 499, 1932. 



Coahuila, Mexico. Amer. Journ. Sci., vol. 239, pp. 407-411, 1941. 



Boguslavia, Siberia, U. S. S. R. Amer. Mineral., vol. 26, pp. 546-550, 1941. 



Average of 6 Chilean hexahedrites. Amer. Mineral., vol. 26, pp. 546-550, 1911, 



Octahedrites. — More abundant in nature than hexahedrites and 

 with a wide range of structural and chemical composition are the 

 iron meteorites known as octahedrites. If etched sections of this 

 group are carefully observed there will be noticed areas which have 

 etching lines similar to those displayed in the hexahedrite group. 



501591 — 43 17 



