204 SMITH— PARAGENESIS OF MINERALS. [Octobers, 



in which some secondary mineraHzation has occurred. This fact 

 too, is now so commonly recognized by petrographers familiar with 

 the rocks of California that no further discussion is needed. 



However, if the pseudodiabases do not show the remarkable 

 phenomenon of the formation of a pseudo-igneous rock out of a 

 sandstone, they do show something equally interesting, — the very 

 beginning of the formation of a metamorphic out of an igneous rock. 

 In some of the pseudodiabases and pseudodiorites all the original 

 minerals and the original texture are still present, and the pyroxenes 

 are only partly uralited to form hornblende. In others the read- 

 justment has gone a little further, the feldspars have been partly 

 changed to a saussuritic mass, and some secondary epidote and 

 actinolite formed out of the pyroxene. In still others the feldspar 

 has been entirely decomposed and a little soda taken from the albite 

 molecule and added to the ferro-magnesian minerals, forming a 

 little glaucophane or other soda-bearing amphiboles. In still others 

 the original pyroxenes, even, have all been decomposed, and abundant 

 epidote, diopside, glaucophane and white mica formed by the read- 

 justment. There are all possible gradations from the little altered 

 diabase to the entirely recrystallized glaucophane schists. The ig- 

 neous rocks described as pseudodiorites, pseudodiabases, and four- 

 chites are widely distributed in the Coast Ranges in the pre- 

 Cretaceous, or Franciscan series, and have been the original materials 

 out of which much of the basic glaucophane schists was made. 

 Analyses of them are quoted below to show their perfect agreement 

 with normal igneous rocks, and their unlikeness to any sediments 

 except tuffs. 



Widely distributed in the Coast Ranges occurs a group of rocks 

 in which the metamorphism is more complete than in the pseudo- 

 diabases and pseudodiorites. The original feldspars are all decom- 

 posed, the pyroxenes either uralited or entirely recrystallized as 

 other minerals, and secondary actinolite, epidote, zoisite, glaucophane 

 and mica are formed. These rocks are massive, often occurring in 

 the form of dykes, but they could hardly be called metadiabases, since 

 some of them were certainly diorites, and others of them were prob- 

 ably made from the alteration of tuffs. They could hardly be called 

 actinolite schists, since some of them contain little actinolite, and 



