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University of California Publications. [Geology 



Then in the table on page 216 we would expect to find under 

 the glaucophane schist that B/A=l. 00, and that G/A=G/B. 

 But B/A as measui'ed on one face gives .961 ; and computed from 

 the two other fa Ce s,C/A^C/B=B/A=. 743/.769=. 966. 



The lawsonite in the rock may explain this discrepancy. This 

 mineral makes up from 5 to 30 per cent of the rock. It gives 

 the rock a tendency toward gneissic structure, some portions 

 being almost free from it, others very largely composed of it. 

 The rock slide parallel to the end shows elongated sections with 

 both C and £) parallel to the elongation, and also parallel to A. 

 The side slide shows more nearly square sections; they are not 

 as uniformly oriented, nor are they as numerous. 



The base shows very much albite and all kinds of orientation 

 of the lawsonite. Of the latter most sections are elongated, and 

 C is always perpendicular to the elongation. 



No data are available for the thermal conductivity of either 

 glaucophane or lawsonite. If the glaucophane were the only 

 constituent, we might work backward and get a general idea of 

 the relative thermal conductivities of this mineral. As it is, 

 the study of this rock is of no value for our work. However, 

 it throws some further light on the structure of schists, and 

 strengthens the idea that the structure of the rock in itself has 

 no effect upon the elasticity of the ether in different directions, 

 but that the thermal conductivity of the rock is the sum of the 

 thermal conductivities of the constituent minerals. 



The Quartzose ScJiist {Whetstone) . — This rock is used as a 

 whetstone. It comes from Telemarken, west of Laurdal, Nor- 

 way. The constituent minerals are muscovite, quartz, calcite, 

 magnetite, and biotite. 



In the bottom and side slide the quartz appears in unelon- 

 gated grains.* There is no uniform orientation, as is seen by 

 all heights of interference colors, and all orientations of the 

 axes of elasticity. The quartz nearly all shows a stepping of 

 the colors with the Nicols crossed. This is due to the angular 

 nature of the fragments. In addition to this evidence of hard 

 usage, the quartz shows conditions of strain at present. It appar- 

 ently makes up over 70 per cent of the rock. 



