Mineralogy and Geology. A37 
_ Pyrovene.—R. Hermann has applied his principles of “ Heterome- 
tism” to several minerals referred by him to the Pyroxene series. (J. 
f. pr. Chem., lvii, 193). The paper hardly admits of an abstract. 
On the Chlorite of Achmatovsk, in the Urals.—M. Koxscuarov has 
described and figured some remarkable crystals of the chlorite of Ach- 
matovsk, (Verhandl. der min. Ges. zu St. Petersburg, 1850-1851). 
The form is rhombohedral, and hemihedrally so (or tetartohedral, to 
the hexagonal prism.) There is a resemblance in some of them toa 
common form of specular iron. One of the crystals is nearly 6 milli- 
meters in diameter, and is remarkably perfect and symmetrical in its 
faces. The others are 1 to 14 millimeters across. Figures 4, 5, 6 
4, i 
Re Raigg 4g,’ gp: g—152° 3, R: $2152" 82, P: 2—102" 10, 
Pere 55’. Borg of the other angles determined by Kokscha- 
