204 THE MINERALS OF NEW SOUTH WALES. 



The amorphous black vesicular pleonaste occurring on the 

 Mudgee Diamond Fields was examined by the late Dr. A. M. 

 Thomson ; he found it to have the following composition : — 



Silica and undecomposed. . . ... 2*75 



Alumina 

 Sesquioxide of chromium 

 Magnesia ... 

 Protoxide of iron. . . 



64-29 

 4-62 



21-95 

 4-49 



98-10 



Sp.gr. = 3-77. 



The colour is dull black, the surface vesicular ; no cleavage, but 

 a highly lustrous well-marked conchoidal fracture ; streak, grey. 



Anhydrous Silicates. 



Kyanite. — Disthene. 



Chemical composition : Aluminium silicate. Anorthic system. 

 Occurs near to Kangaloolah, an arm of Tuena Creek some 10 miles 

 south of Tuena. In colour it is nearly white, the lustre pearly, in 

 slender flattened brittle crystals. 



Stauralite. 



Chemical composition : Aluminium silicate. Rhombic system. 

 Occurs in a talcose schist near Bathurst, in the form of small 

 brown prismatic crystals. 



Andalusite. 



Chemical composition : Aluminium silicate. Rhombic system. A 

 vein of mineral crystallized in rhombic prisms of a pinkish-grey 

 colour occurs in the slate rock to the east of Bungonia. The 

 cleavage is well marked parallel to the o.p. plane; the planes of the 

 prism have a vitreous lustre, but the terminal planes are dull. I 

 hope to have a quantitative analysis of this very interesting mineral 

 finished shortly. 



Ghiastolite (Andalusite variety of). — Chemical composition. 

 Aluminium silicate ; rhombic system. Occurs in granite rock, at 

 Arnprior, Boro (Goulburn), and in small crystals in the slate near 

 Modbury, Shoalhaven. 



Epidote. 



Chem. Comp. Silica, aluminia, lime, iron, etc. : Oblique system. 



Occasionally well-developed columnar crystals have been met 

 with, but I have seen none of large size — also massive. Usually 

 various shades of green. 



