42 Count de Bournon’s Description of a 
aggregation ; and the masses that result from it, no longer offer 
any appearance that can recal to the mind the known cir- 
cumstances of crystallization. The fractures of the mass have 
no lamellated or regular aspect; and very often present that 
which is distinguished by the name of earthy . Such is, in various 
substances, the formation of most of those varieties to which 
Mr. Werner has given the name of compact. 
Many circumstances seem to lead to the idea that, in the 
formation of certain substances, there exists a species of crystal- 
lization by which no determinate form is produced. These sub- 
stances, however, are really the result of a regular crystallization, 
that is to say, of as regular a crystallization as can take place in 
them, and one which cannot be referred to any of the disturbed 
crystallizations of which I have already spoken. This property 
depends, probably, upon the peculiar form of the primitive mo- 
lecules of those substances ; such, for instance, is the globular 
form, or those forms which approach to it : perhaps, however, it 
depends upon other causes. This species of attraction, is what I 
have called amorphous attraction of crystallization ; a name that, 
in my opinion, expresses very properly the nature of its action, 
which appears not to allow the substances on which it acts, to 
take any determinate geometric form, however pure those sub- 
stances may be, or under whatever circumstances that action 
may take place. Calcedony, girasol,* (which substance, when 
in a certain state of decay, is called opal,) and that kind of 
steatite which is perfectly pure and transparent, appear to me 
to owe their origin to this mode of formation. 
* I have long since adopted this word, (which had already been given to one of the 
purest varieties of the above substance,) to distinguish the substance to which Mr. 
Werner gives the general name of opal, and to which the Abbe Hauy gives the 
name of quartz resinite. 
