I906.1 SMITH— PARAGENESIS OF MINERALS. 201 



and the iron and alkali higher. The published analyses that come 

 nearest to that of this eclogite are those of the basalts of Kilauea, 

 Hawaiian Islands, quoted by H. S. Washington/ in which the pot- 

 ash has a similar high percentage. 



Analysis of Eclogite from Coyote Creek, 



Per Cent. 



SiOi 44.15 



AI2O3 10.18 



Fe^Os 1 1.92 



FeO 13.04 



MgO 6.18 



CaO 4.51 



Na.^O 5.11 



K2O 2.09 



P2O5 0.20 



TiOo trace 



H2O (above 100° C.) 0.95 



Total 9931 



A very similar eclogite occurs in a large mass at Hadsell's farm, 

 on the Arroyo Hondo, at the northern end of Calaveras Valley. No 

 analysis was made of this rock, but it is composed of abundant 

 dodekahedrons of red garnet often nearly a centimeter in diameter, 

 long prisms of omphacite, a little titanite, lawsonite, colorless epi- 

 dote, and white mica, probably paragonite. Glaucophane is scat- 

 tered irregularly through the mass, in places making up the greater 

 portion of it, so that the rock might be described as an eclogite in 

 the restricted sense, or as a glaucophane eclogite, according to 

 where the hand specimen was taken. A little albite was found in 

 the slides, but always where the glaucophane was most abundant. 



A very beautiful and characteristic eclogite occurs near Reed's 

 Station on the Tiburon Peninsula, from which Ransome^ first de- 

 scribed the important rock-forrning mineral lawsonite. The rock is 

 massive but grades over into glaucophane schist. It is composed of 

 red garnets from two to three mm. in diameter, with sharply defined 

 dodekahedral faces, long prisms of smaragdite, some green ompha- 

 cite, considerable glaucophane, and pale epidote, numerous large 



' Prof. Papers No. 14, U. S. Geol. Surve}-, 1903, p. 325, Sylvester, analyst. 



" " On Lawsonite, a New Rock-forming Mineral from the Tiburon Penin- 

 sula, Marin Covmty, Cal," Bull. Dept. Gcol. Univ. of California, Vol. I., No. 

 10 (1895), pp. 301-312. 



