Mr Haidinger 07i the Series qf‘CrystaTl'isainon of Apatite. 14l 
qiiently turned out to be Pliospliate of Lime. Being not at all 
a rare substance, although it commonly occurs but in small quan- 
tities, it could not fail frequently to introduce itself to the atten- 
tion of mineralogists, but it cannot be considered as having been 
an established species, before Klaproth discovered its chemical 
nature, and Werner named it Apatite, the Deceiver (from 
uTroerda,) as a species, that had so long deceived naturalists. 
Haliy ascertained the identity of the Spanish and the Saxon va- 
rieties, still considered by Werner as distinct species, under the 
names of Asparagus-stone, and Apatite, the number of which 
he still increased by a third, the Phosphorite, which compre- 
hends the earthy varieties of rhomboliedral Fluor-haloide, 
But whatever opinions may have prevailed on the subject of the 
determination of the species, its crystallisations, at least, have al- 
ways been correctly described, in as far as refers to the system of 
crystallisation ; its forms having, in every instance, been traced to 
the regular hexagonal prism. Many mineral species have been 
less fortunate. It might almost be quoted as a prominent character 
of the earlier period of crystallographic science, that, whilst the 
forms were frequently supposed more regular than they after- 
wards proved to be, the small additional facets were almost en- 
tirely neglected. By many they were considered as accidental 
modifications of those forms, which take the greater share in de- 
termining the general aspect of the crystals, and which, as mere 
modifications, do not tend to confer any thing towards a more 
accurate knowledge of the species ; by others they were entirely 
overlooked, or, on the other hand, completed according to some 
prepossession, in favour of the greatest regularity that possibly 
could be introduced, in representing the forms of the species. 
The last was the case, when Haiiy undertook to describe those 
inclined faces of the crystals of apatite, which do not produce 
any horizontal edges of combination with those of either of the 
two regular six-sided prisms. These inclined faces are contain- 
ed in his VariHe douhlante from St Gothard, which he describes 
in the Tableau Comparatif, and gives a representation, of which 
Fig. lo Pi. V. is an exact copy. In that variety, the faces w, be- 
longing to a scalene six-sided pyramid, derived from R are 
said to appear by pairs contiguous to each of the angles produced 
by the faces S(B) and P-p (s and M). This, however, does 
