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EXPLANATION OF PLATES 
PLATE 1 
a, Pima County, Ariz. During the fall of 
this iron through the air the surface was 
heated by air friction until the metal flowed. 
Such structures are known as flight markings. 
b, Allegan, Mich. The crust on this freshly 
fallen stony meteorite is black, checked, and 
smooth because the stone is friable, hence 
easily eroded away by the air during flight. 
PLATE 2 
A portion of the meteorite exhibit in the 
U. S. National Museum. ‘The three large 
iron meteorites in the foreground are, from 
left to right: Drum Mountains, Utah; Can- 
yon Diablo, Ariz.; Owens Valley, Calif. 
These show characteristic surfaces of iron 
meteorites. The pittings are frequently re- 
ferred to as thumb marks. 
PLATE 3 
a, Sardis, Ga. The dark area at the left 
shows the weathered surface with no char- 
acteristic meteoric features. The dark 
border surrounding the metal and the net- 
work of veins extending into the unaltered 
metal show how alteration attacks an iron. 
The surface of this fragment resembles a 
sandstone, because sand grains from the 
beds from which it was recovered have been 
bonded together by the iron oxide (rust) from 
the buried meteorite. 
b, Bennett County, S. Dak. A remarkably 
large single crystal of kamacite. The delicate 
series of parallel bands are known as Neumann 
lines. This type of meteorite is a hexahedrite. 
The dark inclusions are troilite (iron sulfide). 
This iron contains 5.25 percent Ni. 
PLATE 4 
a, Aggie Creek, Alaska. A medium octa- 
hedrite. The narrow lathlike bands are 
kamacite and each is bordered by delicate 
lines of another alloy of iron and nickel, 
ANNUAL REPORT SMITHSONIAN INSTITUTION, 1948 
taenite (not discernible in this picture). This 
iron contains 8.54 percent Ni. 
b, Edmonton, Ky. A fine octahedrite. 
The kamacite bands are narrow. The dark 
angular areas enclosed within the kamacite 
bands are plessite, which is an unresolved 
mixture of kamacite and taenite. The large 
dark inclusion, left, is troilite. There are 
several large, irregular, elongated kamacite 
areas, light-colored in the picture, which are 
unconformable to the fine octahedral pattern 
of this meteorite. This iron contains 12.57 
percent Ni. 
PLATE 5 
a, Wiley, Colo. Iron meteorites lacking a 
well-developed etch pattern are classified as 
ataxites. The small spindles are kamacite. 
This iron contains 11.71 percent Ni. 
6, Mt. Vernon, Ky. The dark mineral is 
olivine and the light-colored areas are metal. 
This type of a meteorite is known as a 
pallasite. 
PLATE 6 
a, Roy, N. Mex. Stony meteorites con- 
taining these rounded bodies are classified as 
chondrites. The large chondrule consists of 
bands of olivine separated with a black glass. 
b, Elm Creek, Kans. Several different 
kinds of chondrules may occur in the same 
meteorite. One of these chondrules contains 
a euhedral crystal of olivine surrounded by 
the same mineral but with a different struc- 
ture. The other chondrule consists of sep- 
arate fragments of olivine. The ground mass 
is composed of broken fragments of minerals 
in a black glass. 
c, Tennaselm, Esthonia. A chondrule sur- 
rounded by a rim of metal. Many colorless 
areas in the ground mass are metallic inclu- 
sions. Metal rarely occurs within a chondrule. 
d, Moore County, N. C. A thin section of 
a meteorite containing no _ chondrules. 
Meteorites of this type are called acondrites. 
They have structures more comparable to 
terrestrial rocks than any other group of 
meteorite. The dark areas are pyroxene 
minerals and the light areas are feldspars. 
