A428 , Scientific Intelligence. 
of the prism the cross does not stand in the direction os ie principal 
axis and the system is thus distinguished from the Trim 
Through the orthodiagonal planes the cross stands in Ki -dirciiion of 
the principal axis. Through the clinodiagonal-planes it is not in the di- 
rection of the principal axis. ese planes comport themselves very 
different from the similar ones in the rhombic system. 
Through the clinodiagonal domes the cross also appears revolved. 
Ex. orthoclase, augite, cane sugar, gypsum, borax, bicarbonate of pot- 
‘ash, glauber salt, euclas 
TRICLINIC Seeekitp=Phs cross is oblique upon all planes, if an edge 
of the prism be placed meaning with the axis of the tourmaline. Ex., 
kyanite, bichromate of ash. 
Boracite is plainly doubly refractive. Yellow prussiate of potash is 
optically binaxial. Prof. von Kobell describes peculiarities in several 
species, which are here Ses 
IL MINERALOGY AND GEOLOGY. 
1. Mineralogical Notes ; by T. S. Hunt.—Pyrrhotine.—This spe- 
cies with the fornvala Fe, S,, is regard by Laurent as a_protosul- 
phuret in which a portion of iron exists as ferricum, (fe) with two-thirds 
its ordinary equivalent; the Sata of the mineral is then (Fes fes)S« 
According to Schaffgotsch, some varieties have the composition FeS, 
PeySs= Fes Sy or (Fe feg) Sy, corresponding to magnetite FegO4 or (Fe fes)Ou. 
By thus —e it as a protosulphuret, its relation to Greenoekite is 
more apparen 
Wilsonite. The further examination of specimens of the mineral 
Wilsonite in the possession of Prof. E. J. Chapman has shown him 
that the form of this mineral is triclinic with inclination to the right. 
He gives as approximations the psa angles obtained by the 
common goniometer with cleavage su Pe T x= 9 Lo 
145°; T:e = 129°; P:M and T:M= 110° to 125". Clenvade 
perfect with P and T, less so with M. The cleavage with e, ator 
ing to Chapman, “ is not easily obtained, but is very distinct and even. 
Density 2°77. Hardness 3°5 cn the more facile cleavages, and their 
combination edges; 5:5 on the ends of the prismatic concretions.” 
carbonate of lime in the specimens which | had previously analyzed, 
and I have since found that the finely pulverized mineral yields up al- 
most the whole of its lime to cold dilute hydrochloric acid, which does 
not attack the er This still retains its rose color, mee is a hydrous 
micae of alumina and potash, with a little magnesia. The results of 
the analyis by myself of two specimens thus purified, (1 and 2,) and a 
pail analysis kindly furnished me ey Prof. _—- of a ory are a8 
follo 
Silica, - . - Po 50 47-70 a7 42 
gnesia, - = - 4°25 4°14 “73 
Pota + - . - O22 9:38 
.° - . - - ‘95 
i OP f-. 39 42 
