{40 ‘M. Godon’s mineralogical observations. 
some doubts on the supposed simplicity of this mimeral, and endeay. 
our to inquire from the circumstances, which accompany it in nature, 
whether an apparent homogeneity may not conceal an aggregation of 
elements (I mean of simple minerals), in a state of tenuity, which will 
not permit them to be perceived by our senses. 
The mineralogic ‘soil, which is now under our observation, ap- 
pears well adapted to diffuse some light on this subject. Most of the 
different varieties of petrosilex known, being found in great plenty in 
this part of Massachusetts, and their intimate analogy with the fe/ds- 
path porphyre and klingstein porphyre of Werner being evinced by 
observation, I unite them all under the general title of petrosilex, admit- 
ting only of two divisions, viz. simple petrosilex and porphyritie petro. 
ning 
— 
silex, under which J arrange the several species and varieties, which I 
“L. Simple petrosilex. 
20., It exhibits an infinite variety of shades of yellowish, whitish 
[Quincy 0, Dorchester 9], greyish, greenish, brown, reddish-brown, 
blackish. It is sometimes found:of a: fine texture and semi-transpa- 
rency, with a white colour, slightly tinged with green [Milton 0] ; 
sometimes with rosy spots [Chelsea O]- I denote this kind, which 
strikes fire with steel, and may be confounded, to the sight, with some 
variety of agate-quartz, by the name of Jlinty. Sometimes the same 
variety presents a slight red colour, verging to the carnation [Dor- 
chester 3, Brushhill turnpike O}. 
21. A variety of a greenish colour falls sometimes into tabulary 
fragments [Dorchester 1], which become sonorous by percussion. 
I give to this variety or species, which is analogous to the kiingstein 
of the Germans, the specific name of sonorous, agreeably to the opin- 
fon 
of some mineralogists, who consider it as_a distinct mineral. 
= 
