Professor Haussmann on Metallurgic Crystallography. 349 
this specimen of crystalline scoria in the Journals of Moll, but 
since that time I have collected such a mass of materials in re- 
gard to this scoria, as to convince me that it is not only produced 
in different iron processes, but also in the melting of copper-ores. 
This crystalline scoria possesses all the properties of perfectly 
formed glass ; its conchoidal fracture, vitreous lustre, transpa- 
rency, brittleness, and hardness. As the light passes over its 
surface, its colour changes from a muddy wine colour to an oily, 
and then into an olive hue ; but by a reflected light cast upon 
its clear and unbroken surface, the colour is of a dark olive 
hue. Occasionally, however, the surface exhibits colours resem- 
bling those of tempered steel. The powder has a green-grey 
colour, and follows the magnet in its natural state, or after being 
gently heated, in which state its colour changes into black. When 
mixed with muriatic acid, it becomes gelatinous. According 
to the analysis of Klaproth, this scoria contains, in the hundred 
parts, the following : 
66.00 Oxide of iron 
29,50 Silica 
4.00 Alumina 
0.25 Potash 
99.75 
Besides these component parts, I have found in it calcareous 
earth. 
Scoria, in the crystalline state, is either octahedral, or it occurs 
in forms which are easily deduced from an octahedron. 
1. The primitive form is a rectangular octahedron. 
I have observed the following secondary crystallizations : 
2. A wedge-like octahedron, or a primitive octahedron, length- 
ened out in the direction of the obtuse edges of the basis. 
3. The same, truncated on the terminating edges. 
4. The same, truncated on the obtuse edges of the basis. 
I found a remarkable specimen of crystalline scoria in the 
furnace of an iron-foundery in Sweden, where the iron flow- 
ing over the furnace was covered with it. It is perfectly vitre- 
ous, of a pearly colour, of a greenish or reddish grey, and with 
very small crystals, collected together in great numbers. It 
has the form of sparry gypsum, with quadrilateral elongated 
plates, the lateral edges being very oblique, the sides acumi- 
nated, and the angles incapable of being accurately measured^, 
VOL. V. NO. 10. OCTOBER 1821. 
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