22 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 92 
the Freda meteorite and also, for comparative purposes, that of other 
known nickel-rich ataxites. 
The general structure of the Freda meteorite is that of an ataxite. 
Tt consists of a fine, acicular groundmass in which are scattered abun- 
dant spindles and particles of kamacite. In appearance this acicular 
structure is similar to martensite in artificial irons and probably had 
an analogous origin, for owing to the high nickel content the gamma- 
alpha transformation was greatly depressed. After the initial trans- 
formation, when the kamacite had separated, the remaining gamma 
solid solution underwent only a partial transformation and the 
kamacite was very sparingly precipitated on octahedral planes, pro- 
ducing an acicular structure similar to that observed in many 
octahedrites. 
Plate 1 shows in natural size the flight markings of this meteorite. 
Plate 2, figure 1, illustrates the general structure at low magnifica- 
tion. The kamacite inclusions are surrounded by clear (white) zones, 
which are areas of taenite from which the kamacite has been attracted 
to the larger masses. In other words, there has been an impoverish- 
ment of the kamacite in these areas and an accumulation of it into 
masses. Many of these kamacite areas contain inclusions of a rounded 
iron-phosphide eutectic. The general acicular groundmass exhibits 
the martensite structure. 
TaBLE 1.—Chemical analysis (in percentages) of the Freda meteorite and other 
nickel-rich ataxites 
| 
| Santa 
Freda | Limestone Creek | San Cristobal Catha- Oktibbeha 
| { rina 
Substance , 
GP: (R. (GIR A eO: (BE. CARAS || CWS: (E. 
Hender- | Knauer,| Jackson, Sjostrom,, Cohen, | Damour,| Taylor, | Coken, 
| son, ana- ana- | ana- | ana- | ana- ana- ana- 
| analyst) | lyst) } lyst) 2 | lyst) 3 | Lyst) 4 lyst) ® lyst) 6 lyst) 7 
— = laminar | SS | | soot! fon 
| yee UP ae Se 6 SA TT 75. 86) 65. 03} 66. 56) 73. 72) 73. 56} 63. 69] 37. 69] 37. 24 
Ni__________________|823. 49] 29. 99] 24. 70] 25. 60] 25. 44| 33. 97] 59. 69] 62. 01 
CSC IE PA i Ne 66), 2.4828 ee 1.00) 1.00) 1. 48 . 40 oie 
| En PH aN A as oe Pa yal} ma | eRe | 1S he eel a a | 05 10 15 
SOE aa ee ee ae mm nel B21 = [a 400) 1 een: | DGS Ree hy SUE aie) 
msoluible: i. sys 2 07 4) | See Pelee ey he ey 0) KL Ene 2 Se 
EN a oe patie Wek OG 2 Tie Sc AN Ne ES a 
Crrand Nini si VOLVER Mein 3. 24)------).-----|----=- eee 
Ci As Vie a a el a TR es EE OE 
1 Meteoritenkunde, 1905, No. 3, p. 131. 
2 Amer. Journ. Sci., vol. 34, p. 335, 1838. 
3 Sitz. Akad. Wiss. Berlin, 1898, p. 607. 
4 Meteoritenkunde, 1905, No. 3, p. 135. 
5 Compt. Rend. Acad. Sci. Paris, vol. 84, p. 48, 1877. 
§ Amer. Journ. Sci., ser. 2, vol. 24, p. 293, 1857. 
7 Ann. Naturh. Hofmus. Wien, vol. 7, p. 146, 1892. 
8J. G. Fairchild, U. S. Geological Survey, determined by methods different from those used by the 
author the nickel content of the same sample and reports 23.27 percent 
