152 MAGNESIA . 



and in the angles of its crystals. Moreover, the crystals are 

 usually stout and thick, and never have the slender bladed 

 form common with hornblende. Some fibrous varieties, 

 however, can scarcely be distinguished except by analysis ; 

 yet it is a general fact, that asbestus occurring where pyrox- 

 ene abounds, belongs to this species, and that with hornblende 

 pertains to hornblende. White crystals of scapolite may be 

 mistaken for this species, especially where two of the pyra- 

 midal faces in a crystal of scapolite are enlarged so as to 

 resemble the oblique roof-like termination of crystals of py- 

 roxene ; but the angle between these faces in the former is 

 136° 7, while it is 120° 32 ' in pyroxene. Their relations 

 to schiller spar and serpentine have already been stated. 

 The species is never yellowish green like epidote. 



Obs. Pyroxene is one of the most common minerals. 

 It occurs in granite, granular limestone, serpentine, basalt 

 and lavas. In basalt and lavas the crystals are generally 

 small and black or greenish black. In the other rocks, they 

 occur of all the shades of color given, and of all sizes to a 

 foot or more in length. One crystal from Orange county, 

 measured 6 inches in length, and 10 in circumference. 

 White crystals occur at Canaan, Conn., Kingsbridge, New 

 York county, and the Singsing quarries, Westchester coun- 

 ty, N. Y., in Orange county at several localities; green 

 crystals at Trumbull, Ct., at various places in Orange coun- 

 ty, N. Y., Roger's Rock and other localities in Essex, Lew- 

 is, and St. Lawrence Co's. Dark green or black crystals 

 are met with near Edenville, N. Y., Diana, Lewis county. 

 Green coccolite is found at Roger's Rock, Long Pond, and 

 Willsboro, N. Y. ; black coccolite, iii the forest of Dean, 

 Orange county, N. Y. Diopside, at Raymond and Rumford, 

 Me., Hustis's faim, Phillipstown, N. Y. 



Pyroxene was thus named by Hauy from the Greek pur 

 fire, and xenos stranger, in allusion to its occurring in lavas, 

 where, according to a mistake of Ha&y, it did not belong. 

 The name augite is from the Greek auge, luster. 



HORNBLENDE. 



Monoclinic In oblique rhombic prisms more or 



What is said of the occurrence of pyroxene 1 How does it differ 

 from hornblende ? how from scapolite ? What is the derivation of the 

 names pyroxene and augite. 



