60 CALIFORNIA ACADEMY OF SCIENCES. [PROC. 30 SER. 



tines so derived is seen throughout the greater part of the 

 slides. 



Areas of a somewhat different fades of the serpentine 

 occur within the talc and garnet-amphibolite area. This 

 rock is hard, compact, occurring massive, and not strati- 

 form. As in the serpentines just described, minute veins 

 of silky chrysotile traverse it here and there. The rock is 

 very dark green, and scattered through it are aggregates of 

 a magnesian mineral, with pearly luster, whose optical prop- 

 erties were not investigated. Besides this mineral, there 

 occurs in various amounts, associated with the compact ser- 

 pentine, a pale green, lamellar mineral with the optical 

 properties of bastite. 



4. TALC-SCHIST. 



The area in which this serpentine is found is largely of 

 talc-schist, usually found as a soft, foliated rock, stained 

 yellow with limonite. It has a silvery luster, and when 

 looked at closely the talc is seen to be of a pale green color. 

 It is quite smooth, with a greasy feel, and is easily scratched 

 with the nail. The rock splits readily along the schistose 

 surfaces. Near the western end of the area, back of 

 Empire Landing, there is a soapstone quarry where is found 

 a facies of the schist, which but little resembles the foliated 

 form just described. This is massive, not schistose, and 

 has a dark gray color with a tinge of green. The rock 

 may be scratched with the nail only in places, showing that 

 it is not wholly talc. The chief difference between this 

 rock and the foliated schist is the presence everywhere 

 through it of a mineral with a pronounced lamellar struc- 

 ture, occurring in moderately small, bladed forms, which 

 are interlaced in all directions. This mineral appears to be 

 the chief constituent of the rock, and at least equal to the talc 

 in amount. It is pale green in color, with a metalloidal luster, 

 and a hardness of about 4. Before the blowpipe it gives 

 the characteristic reactions of serpentine. With a lens the 

 silvery flakes of talc may be seen here and there, besides 

 scattered grains of pyrite. 



