BY W. F, PETTERD, C.M.Z.S. 97 



tions, Heazlewood ; occurs in solid, almost white, radiating 

 bunches at the Comstock Min^e, Zeehan. 



157. Hypersthene (Silicate of Magnesia, Calcium, and 



Iron). 



An orthorhombic pyroxene, related to enstatite, the 

 former being rich in iron, and the latter containing a 

 much smaller amount of that element. On the east side 

 of the Parson s Hood Mountain this mineral occurs with 

 Schiller spar and diallage rock. Fairly abundant at the 

 Heazlewood ; on the Forth River ; Meredith Range ; Dun- 

 das. ''Thin sections of gabbro received from Mr. V^ . R,. 

 Bell as occurring in the Parson's Hood Range show under 

 the microscope crystals of hypersthene more or less con- 

 verted into bastite." (Ulrich.) In granite, St. Mary's 

 Pa5s. 



158. Hydronephelite (Hydrous Silicate of Sodium and 



Aluminium). 



This zeolite commonly occurs as a white massive mass, 

 usually having a strongly perceptible radiating structure; 

 it also affects a tufted habit when occurring in cavities 

 or vughs. 



It has been detected in the elaeolite syenite of Port 

 Cygnet, and at the Shannon Tier. It is remarkably abun- 

 dant in the nephelinite of the latter locality. In some 

 instances the mineral occurs in rather large patches, which 

 are snow-white, and thus strongly contrast with the 

 intensely black augite and grey base of the rock. 



159. Idocrase (Basic Silicate of Calcium and Aluminium). 

 Also known as vesuvianite. This species is a member of 



the tetragonal system. The general form of the crystals is 

 a rectangular prism, terminated by planes, with the edges 

 of the prism sometimes replaced. The facets are highly 

 polished. It occurs at the Hampshire, near the old silver 

 mine, often massive, closely intermixed with brown garnet, 

 with patches of highly-coloured amethystine quartz, and 

 thus forming attractive specimens ; about a mile north- 

 west of the Shepherd and Murphy Mine, at Middlesex, it 

 occurs associated with much magnetite; sparingly found at 

 Anderson's Creek, near Beaconsfield. 



160. Iodyrite (Iodide of Silver). 



This rare ore of silver crystallises in the hexagonal 

 system, with a hemimorphic habit. The colour is pale 



