180 N. von Kokscharov on the Clinochlore of Achmatowsk. 
According to G. Rose, the Clinochlore of Achmatowsk has the 
following characters: B.B. on charcoal intumesces, becoming yel- 
lowish brown and opaque: in the platinum forceps, fuses with a 
strong heat on the outer edges to a black glass. In a tube under- 
goes the same changes as on ial giving little water with no 
fluoric acid. With borax dissolves easily to a clear glass, colored 
fuses with difficulty. With sulphuric acid wholly decomposed. 
8 lyses by von Kobell (J. f. pr. Ch. xvi, 470), Varrentrapp, (G. 
Rose, Reise n. d. Ural, 1842, ii, 127 and Pogg., xviii, 189) and 
Marignac (Ann. de Ch., De 430). 
Fe Mn Mg Tf Insol. 
i gi-14 17°14 3°85 0°53 3480 12:20 O8==100 1 
2. 30°38 1697 487 et e807 12°63 83 
3 80°27 19:89 #e 4-42 sea 8-138 12°54 =100° - 
Varrentrapp deduces the formula, 
(Mg, Fe)? Si+Al SiteMg H?. 
This composition does not differ from that of the Clinochlore of 
Pennsylvania 
I shall hee to revise my comparisons of the described chlorites, 
after this reference of the Achmatowsk mineral to the monoclinic 
system, with the exception of the Schwarzenstein chlorite (ripi- 
dolite of v. Kobell), as they cannot stand, since we do not know_ 
to which zone the ea: planes of these chlorites belong. I 
may here observe that none of the angles obtained, by Frobel 
and age ae in Pennine, are yet found in either of the zones 
of the wsk chlorite. The same is true of the Kammer- 
erite. Thet it slance of the clinochlore crystals to hexagonal 
forms, renders it desirable that there should be a revision of the 
erystallography of all these minerals. 
The optical characters of our crystals have not yet been fully 
studied. Ican only state that the lamine of the Achmatows 
clinochlore examined with the tourmaline, allows the light to 
pass when the axis of the tourmaline plates are at right angles— 
in Which respect it does not differ from biaxial crystals. There 
is a strong probability ihérafon that the optical characters are 
like those of the Pennsylvania Clinochlore. In this last, Mr. W. 
P. Blake, examining a triangular plate, found that the two axes 
lie in the same plane which was at right angles with one side of 
the triangle; and this plane therefore lies in a clinodiagonal sec- 
tion. According to lake, one of the optical axes is inclined at 
an angle of 27° 40’, and the other at 58° 13’, making the angle 
between them 85° 53’ and 94° 7’. 
Mr. Blake has observed in another specimen a second system 
of axes, the aig of which makes an angle of 60° with the first, 
ich indicates that the specimen was a compound crystal. 
