SN eee ne et ee ae ere ae el 
ee ee 
Review of Cleaveland’s Mineralogy. 43 
lography, physical and external characters, and chemical char- 
acters. et . 
He has given a clear view of the Abbé Haity’s curious dis- 
eoveries regarding the six primitive figures or solids which 
form the bases of all crystals—the three integrant particles or 
molecules which constitute the primitive forms, and of the 
theory by which it is shown how the immensely numerous and 
diversified secondary or actual forms arise out of these few 
elementary figures. 
This is certainly one of the most singular and acute disco- 
veries of our age. It is true, there is a difference of opinion 
among mineralogists as to the practical use of crystallography 
in the discrimination of minerals. Some dwell upon it with 
excessive minuteness, and others seems restless and impatient 
of its details. The truth seems to be, that those who under- 
stand it, derive from it (wherever it is applicable) the most 
satisfactory aid ; and it requires only a moderate knowledge of 
geometry to understand its principal outlines. On the other 
hand, it is no doubt possible, in most instances, to dispense 
with its aid, and to discriminate minerals by their other pro- 
perties. 
Of the external and physical characters of Mr. Werner, Mr, 
Cleaveland has given a clear account, combining into the same 
view the fine discriminations of the French authors, particu- 
larly regarding refraction, phosphorescence, specific gravity, 
electricity, chatoyement, and magnetism. ‘The same may be 
said of the chemical characters. We do not know a more 
satisfactory and able view of the characters of minerals than 
Professor Cleaveland has exhibited. 
We would however ask, whether, in enumerating the kinds 
of lustre, the term adamantine should not be explained, as it is 
not understood by people in general, while the terms denoting 
the other kinds are generally intelligible ; whether in the enu- 
meration of imitative forms, lenticular and acicular should not 
rather be referred to the laws of crystallization ; whether reni- 
form and mamillary are synonymous ; whether sandstone, as 
being a mere aggregate of fragments, is a good instance of the 
granular fracture ; whether in its natural state (at least the 
