58 
Troost on the Pyroxene. 
ble crystals. It offers various forms which are proper to 
this substance — we have 
Cylindroid P. The crystals of the Sahlite, Diopside^ and 
Mussite, are often marked by longitudinal striae or small 
channels, which give them a cylindrical appearance. 
Lamellar P. The Sahlite is remarkable by its lamellar 
structure — It occurs in great or small lamellae. It offers 
also very small lamellar particles, in which case it belongs 
to the Grano-lamellar variety. The *dugite P. is also some- 
times lamellar. 
Compressed P. The crystals of the Mussite exhibit often 
this form. 
Granular P. This structure is proper to the variety 
Coccolite. It occurs also in the green Volcanic Pyroxene^ 
and in the t^ugite, 
Fibro granular P. This is the variety Mussite. 
Fasciculated radiated P. In masses formed by the union 
of prisms as bundles or rods, fascicular — This occurs in the 
Island of Elba with the Yenite, and in the Mussite. 
Fibrous P. This variety differs from the former in the 
prisms being more slender, which make it resemble some 
varieties of Asbestos. 
Shistose P. Formed by a lamellar accumulation, as in 
the Mussite, and a variety found at Franklin, called Jeffer- 
sonite. 
Resinoid P. This variety is black, having the appear- 
ance of pitch, and is void of all appearance of any crystal- 
ine structure. It belongs to the Volcanic Pyroxene. 
Having now exhibited the different characters and man- 
ners in which the Pyroxene offers itself to our observation, 
