246 DESCRIPTIONS OF MINERALS. 
tions—the light colored, the dark colored, and the thin 
foliated. 
I. Malacolite or white augite is a calcium magnesium 
pyroxene, and includes white or grayish-white crystals or erys- 
talline masses. Diopside, of the same eRe sition, occurs 1n 
ereenish-white or grayish-green crystals, and cleavable masses 
cleaving with a bright smooth surface. Sahdite contains 
iron 1 ‘addition, and:is of a more dingy green color, has less 
lustre and coarser structure than diopside, but is otherwise 
similar; named from the place Sahla, where it occurs. 
Faussaite contains a little alumina in addition to the ele- 
ments of sahlite, and is found in erystals of rich green shades 
and smooth and lustrous exterior. ‘The name is derived 
from the foreign locality Fassa. Coccolite is a general name 
for granular varieties, derived from the Greek coccos, grain. 
The green is called green coccolite, the white, white coccolite. 
The specific gravity of these varieties varies from 3°25 to 3°3. 
Asbestus. This name includes fibrous varieties of both 
pyroxene and hornblende ; it is more particularly noticed 
under the latter species, as ‘pyr oxene is rarely asbestiform. 
Il. Augite includes the black and greenish-black crystals, 
which contain a larger percentage of iron, or iron and mag- 
nesium, and which mostly present the form in figure 1. Spe- 
cific gravity 3°3-3°4. This is the common pyroxene of erup- 
tiverocks. Hedenbergite, an iron-calcium pyroxene, is a green- 
ish-black opaque variety, in cleavable masses affording a 
greenish-brown streak ; specific gravity 3°. Polylite, Hud- 
sonite, and Joffersonite, fall here ; the last contains some 
zine oxide. ‘hese varieties fuse more easily than the pre- 
ceding, and the globule obtained is colored black by the 
iron oxide. 
III. Diallage is a thin-foliated variety, often occurring 
imbedded in serpentine and some other rocks. It differs 
from bronzite and hypersthene in crystalline form, and in 
being fusible. 
Obs. Pyroxene is one of the most common minerals. It 
occurs 1n almost all basic eruptive rocks, like doleryte, as an 
essential constituent, and is frequently met with in rocks of 
other kinds ; common also in granular limestone. In basalt 
the crystals ‘ure generally small and black or greenish black. 
In the other rocks, they occur. of all the shades of color 
given, and of all sizes toa foot or more in length. One crys- 
tal from Orange County, measured 6 inches in length, and 
(oe eee: De 
