Saussure's One cannot too often repeat that there must be found in 



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INTRODUCTION. 



ften repeat that 

 observations. the mineral wor]( ^ and that in efl f ect in it are found, all the 



mixtures in all imaginable proportions, from which proceed 

 an infinite number of mixed and undetermined kinds. 



" If in the kingdom of organised beings, where the spe- 

 cific forms are determined by the seeds, it is often difficult to 

 mark the limits of the species ; how much more so to ascer- 

 tain them in one where only the force of cohesion unites the 

 elements, whatever be their nature, and in whatever propor- 

 tion chance collects them. 



" It is for this reason that in this work I have avoided 

 giving names to the stones I have written of, when I have 

 not been able to ascertain them by decided marks, which 

 could fix their place in the known system of the nomen- 

 clature. 



" Those who collect, and the nomenclators properly so 

 called, do not like these doubtful sorts, which it is too diffi- 



~ 



even reject them entirely, because they appear to reproach 



the imperfection of their systems. For this reason one sees, 

 in the greatest number of cabinets, only the sorts whose cha- 

 racters are decidedly known. There nothing stops you, all 

 is conformable to received systems, and all have fixed names. 

 But when nature is studied by herself, when one proposes, 

 instead of finding cabinet specimens, to study minutely all 

 the productions of the mineral kingdom, and is at the same 

 time jealous of a certain degree of precision, one finds at 

 every step individuals which it may be said to be impossible to 

 arrange under known denominations. One may then mark 

 the bounds 5 one may determine how far each individual ap- 

 proaches to, or recedes from, such and such a species -, but 

 one cannot positively affirm the name of the one or other of 

 these species."* 



* Saus&ure, ii. 606. 



cult to arrange under the known genera. They neglect or 







