192 SMITH— PARAGENESIS OF MINERALS. [Octobers, 



dite is very common in the glaucophane schists and eclogites, 

 in long slender prisms and needles, with small extinction angles, 

 and pleochroism from pale to bright grass green. This is 

 often intergrown with glaucophane, and frequently shows replace- 

 ment rims of that mineral. It sometimes results from the alteration 

 of primary hornblende in the rocks, but more often from the ural- 

 iting of pyroxenes. Whether the smaragdite is soda-bearing has 

 not been determined by analysis. Probably there is a complete 

 intergradation between pargasite, carinthine and actinolite. The 

 analyses quoted below show the composition of the bluish green 

 actinolite from Berkeley and San Pablo, of the pargasite from 

 Calaveras Valley, Santa Clara County, California, and for com- 

 parison the composition of carinthine from the Alps, of pargasite 

 from Finland, of typical actinolite (smaragdite) from Lake Geneva, 

 and of an artificial amphibole with the same chemical composition 

 as pargasite. 



Diopsidc. — The pale green variety of diopside without terminal 

 planes, and with very high double refraction, known as omphacite, 

 is rather common in the basic glaucophane-bearing rocks, especially 

 in the eclogites. It is quite abundant in the eclogite from near San 

 Martin, Santa Clara County, California, and also occurs in the 

 glaucophane-lawsonite eclogite of Reed's Station near Tiburon, Cali- 

 fornia. In appearance it resembles actinolite closely, but differs in 

 its cleavage, and its high extinction angle in clinopinacoid sections. 



The augite with fine orthopinacoid cleavage known as diallage, 

 while essentially characteristic of igneous rocks, has been found in 

 the eclogite of the Junction School-house near Healdsburg, as a 

 secondary mineral associated with red garnet, glaucophane, mar- 

 garite and titanite. 



Epidote. — This mineral is very common in the basic meta- 

 morphics of the glaucophane series, but it is not the deeply colored 

 mineral usually found in contact products. It is colorless, without 

 pleochroism, and the interference colors in thin slides are not above 

 the bottom of the second order. The crystals are elongated parallel 

 to the symmetry axis, and consequently most sections give rectan- 

 gular parallelograms with rather distinct cleavage parallel to the 

 symmetry axis, and the optical figure across the plate. This variety 



