366 Review of Dana’s Mineralogy. 
Following the order of his crystallographic system, Mr. Dana 
unfolds this intricate subject by a beautiful series of figures, of 
which we can notice only the following :—. 
‘“‘Figure 3 represents a crystal of Galena from Rossie. 
shortened cube ; the lateral faces are very irreg- 
ularly curved, and consist of the primary faces 
of the cube and the planes truncating the lateral 
edges. Some of the terminal edges are also 
truncated. The crystal is surrounded by a low 
pyramid, consisting of four planes on each of the SS = 
angles and edges, which, owing to the distortion, ‘ 
do not occur elsewhere on the crystal. The 
cleavages of the crystal easily explain the relations of the several 
planes to the primary.” 
‘Figure 5 of apatite is the same form that is represented in figure 4, 
but greatly distorted. The planes e’, e, e”, between P and the right M, 
Fig. 4. Fig. 5. fl 
It is a 
are enlarged, while the corresponding planes below are in part oblitera- 
ted. By observing that similar planes are lettered alike, the two figures 
may be compared throughout.” 
Fig. 6. 
N 
SP, 
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ANN 
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= 
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HTH 
HAH 
ile 
i 
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A’ 
AS 
HAN 
SS 
** Curved Crystals—Curves in imbedded crystals are of frequent o¢- 
currence; and in implanted crystals they are not very uncommon. 
annexed figure of quartz, (fig. 6,) illustrates this kind of distortion ; the 
& 
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