441 



PART II.-ORYCTOGNOSY. 



J. HIS branch of mineralogy, as already explained, 

 makes us acquainted with all the properties and rela- 

 tions of simple minerals. In treating this subject, we 

 shall consider it in the following order : 



1 . Describe the character of simple minerals. 



2. Explain the system of arrangement. 



3. Describe the different species according to their 

 external characters and chemical composition ; and trace 

 their geognostical and geographical distributions ; and, 

 lastly, explain their various uses. 



1 . Character* of Simple Mineral!. 



Cbancteri The characters of minerals are of different kinds, viz. 

 h ttntal Chemical, Phyiical, Geogntutical, and Ceo- 



1 . External Character!, are those which we disco- 

 ver by means of our senses, in the aggregation of mi- 

 nerals, and which have no reference to their relation to 

 Other bodies, or to chemical investigation*. 



2. Chemical Character*, are those winch are afford- 

 ed by the complete analysts of the mineral, by trials 

 with the various re-agents, the blowpipe, and the pyro- 

 meter. 



3. Fhytical Character!, are those physical pheno- 

 mena which are exhibited by the mutual action of mi- 

 nerals and other bodies ; such are the magnetic and 

 electric properties exhibited by some minerals. 



4. Geognottical Character*, are those derived from 

 various geognostic relations of minerals. 



5. Geographical Character!, are derived from the 

 geographical distribution of minerals. 



\Ve shall first consider the external characters, nd 

 then the others, in the order already mentioned. 



External Character! of Minerali. 



The external characters of minerals are either gene- 

 characurt ric or tpfci/ic. The generic characters are certain pro- 

 of mine- pertie* of minerals used as characters, without any re- 

 ference to their differences, as colour, lustre, or weight. 

 The differences among these properties form the spe- 

 cific characters, as adamantine lustre, and gtanr r 

 vitreous lustre. The generic characters are divided in- 

 to gtmeral and particular. Under the first, are com- 

 prehended those that occur in all minerals, whether so- 

 lid, friable, or fluid : under the second, those which 

 occur only in particular classes of minerals. In the 

 following tabular view, the external characters are ar- 

 ranged nearly in a natural succession, and in the order 

 in which they are employed in the descriptions of mi- 

 nerala. 



VOL. Vr. PART II. 



rats. 



A Tabular Vie* of the Generic external character! o/Oryctogno- 

 Minerals. ij. 



GENERAL GENERIC EXTERNAL CHARACTERS. General 



generic ex- 



1. Colour. ternal cha- 



2. The Cohesion of the Particles, according to which racier*. 



minerals are distinguished into 



Solid, 



Friable, 



Fluid. 



Remaining general generic external character!. 



For the touch 



For the smell. 

 For the taste. 



rs. 



r 



Is. 



The Unctuotity. 



The Coldness. 



The Weight, 

 fi. The Smell. 

 7. The Taste. 



IB 



