1084 NOTES AND EXHIBITS, 



a hornblendic mineral strongly dichroic, magnetic iron, a few flakes 

 of biotite, together with quartz grains and concretions of fibrous 

 radial zeolitic material also enclosing free silica. . The felspars 

 are mostly clear and show polysynthetic twinning. The horn- 

 blende (?) is interstitial filling in the spaces between the felspars, 

 and appears to be an alteration product. The quartz is seen 

 principally in and near the zeolitic concretions, and appears to be 

 derivative. 



A similar rock but more finely crystalline and homogeneous, and 

 containing less free silica has been observed by the author in the 

 Vegetable Creek District, near portion 121, parish of Wellington 

 Vale. 



(3) On a Pitchstone from Port Stephens, showing faint perlitic 

 structure : — 



The miscroscope shows this pitchstone to consist of a pale 

 brownish-yellow semi-translucent base, with long and short wavy 

 threads of clear glass, following the lines of flow. The whole 

 field remains dark under crossed nicols. The glass is traversed 

 by occasional gas-pores, and shows faint perlitic structure. The 

 age of this pitchstone is not known. Possibly the pumice deposits 

 found on the East of New South Wales may be connected with it. 



(4) On the occurrence of Chiastolite in a Stone Hatchet found 

 at Strathl)ogie, near Vegetable Creek : — 



The author is not aware that this mineral has been previously 

 discovered in New South Wales. The rock in which it is found is 



a very remarkable variety indeed, quite unlike any rock known to 

 the author, so that it is impossible for him to class it. 



The rock consists chiefly of closely packed spherulitic bodies, 

 about one-fortieth of an inch in diameter, in a dark base, the 

 precise character of which it is difiicult to determine. 



Chiastolite crystals are sjjoradically distributed with tolerable 

 frequency through the base, and can be recognised as clear rhombs 

 crossed by diagonals of dusty magnetite. Several of the crystals 

 are bounded externally by a black opaque zone. All are doubly 

 refracting. 



