202 SMITH— PARAGENESIS OF MINERALS. [Octobers. 



crystals of lawsonite, and plates of margarite. Sphene is scattered 

 through the mass. In places the glaucophane is so abundant that 

 the rock might appropriately be called a glaucophane eclogite. 



Some of the California eclogites are remarkably like those of 

 Syra in the Grecian Archipelago, from which glaucophane was first 

 described. This resemblance is especially strong in the glauco- 

 phane eclogites of Camp Meeker in Sonoma County, and of the 

 Junction School-house near Healdsburg. These are massive rocks 

 made up of dodekahedral red garnets, and long prisms of glauco- 

 phane, with a little colorless epidote, and patches of titanite. A part 

 of the Healdsburg eclogite is peculiar in having secondary diallage 

 and secondary labradorite along with red garnet and margarite, 

 and in showing replacements of both diallage and margarite by 

 glaucophane. In both the Healdsburg and the Camp Meeker eclog- 

 ites the garnets almost invariably show a kelyphite ring, or reaction 

 zone, where mica has developed apparently at the expense of 

 the garnet. 



A new type of eclogite was described from Calaveras Valley by 

 R. S. Holway.^ This rock is composed of anhedrons of garnet and 

 short thick prisms of an amphibole that is black in reflected light, 

 and greenish blue in transmitted light. It fuses readily to a black 

 magnetic globule, coloring the flame yellow, showing the presence of 

 considerable sodium and iron. The pleochroism is intense, the a 

 ray being pale greenish yellow ; the t ray, deep olive green ; and 

 the C ray, greenish blue. The extinction angle of (?t on c is about i8°. 

 This mineral has been determined as pargasite, and the rock called 

 pargasite eclogite. Along with the pargasite some glaucophane is 

 found in rims around the pargasite, and small quantities of white 

 mica, either paragonite or margarite, and a little sphene and rutile. 

 Albite is found as veins in the rock, but not disseminated through it. 

 Colorless epidote is present in considerable abundance in some of 

 the slides. This rock grades over into a pargasite schist or gneiss, 

 without garnet, but considerable albite with small crystals of lawson- 

 ite scattered through it. 



The handsomest eclogite found in California is that of Hilton 

 Gulch on Oak Ridge, about five miles east of Calaveras Valley. This 



^"Eclogites in California," Jour. Gcol., Vol. XII., 1904, p. 351. 



