74 Meteorites and What they Teach us. — Hensoldt 
octahedral crystallization. Now in 1848 another set of lines 
was discovered in certain meteoric irons by Neumann, especial- 
ly in the iron which fell at Braunau in Bohemia in 1847. These 
lines, which are quite different from those above described, 
were found to denote a cubical crystallization and they have 
since been known as Neumann lines. They intersect each other 
at right angles, parallel to the faces of a cube and sometimes 
are traversed by diagonal lines, indicating a twinning of the 
cube. 
The Widmanstattianand Neumann lines have hitherto served 
as a basis for dividing the iron-meteorites into octahedral and 
cubic irons. Dr. Oliver W. Huntington however has success- 
fully shown that such a classification is neither natural nor 
fundamental and that the Widmanstiittian figures and Neu- 
mann lines are sections of planes of crystalline growth paral- 
lel to the three fundamental forms of the isometric system, 
namely the octahedron, the cube and the dodecahedron. 
Analysis has revealed that the cubic irons are purer (less 
alloyed with nickel, etc.) than the octahedral ones and Tscher- 
mak especially draws attention to the fact that in the case of 
artificial irons the pure iron tends towards a cubic crystalliza- 
tion with markings like the Braunau meteorite. This can be 
strikingly observed in the so-called spiegeleisen, a variety of 
cast-iron. 
The element of time is of primary importance in determining 
the crystalline structure of the iron, as during a very slow pro- 
cess there would be a more complete elimination of foreign 
materials than during a rapid solidification. The action of 
the process of crystallization in eliminating impurities pro- 
duces effects with many minerals not unlike those of the Wid- 
manstattian figures, as we may see in rock-sections containing 
leucite, nosean, nepheline, etc.^ That excellent observer Dr. 
Huntington also draws attention to the mica from Chandler's 
Hollow, Delaware, in which particles of magnetic oxide of iron 
are deposited in lines, which are also sections of planes of 
crystalline growth. Plates of this mica present, in the con- 
figuration of their lines, a close analogy to the etched surfaces 
of octahedral meteoric irons. 
Prof. Sorby, in an article published in "Nature" in 1877 (vol. 
'^Vide 0. W. Huntington ' 'On the crystalline structure of iron meteor- 
ites." 
