BY W. F. PETTERD, C.M.Z.S. 7 



when massive extremely tough. They may be divided 

 thus: — 



(1) With little or no Aluminium — 



Actinolite. 



Asbestos. 



Tremolite. 



(2) Containing Aluminium — 



Pergasite, or common hornblende. 



The localities are under the respective headings. 



10. Analcite (Hydrous Silicate of Sodium and Alu- 



minium). 



A zeolite that may be recognised by its isometric crystal- 

 lisation. It is fairly abundant in the haiiyne-porphyry of 

 Port Cygnet and also in the Tertiary vesicular basalt at Bell 

 Mount and vicinity. In the trachydolerite so prominent at 

 Table Cape and Circular Head it occurs in groups of 

 diminutive crystals. As small groups of well-formed 

 crystals in basalt, Penguin River. 



11. Anatase (Dioxide of Titanium). 



This mineral is also known as octahedrite. It is one of 

 the polymorphous forms of TiOg, the others being rutile 

 and brookite. Anatase crystallises on the tetragonal sys- 

 tem, the primary four being the octahedron with a square 

 base. It assumes various shades of brown in colouration. 

 It occurs in this island as diminutive waterworn crystals, 

 and is extremely rare. 



Locality : Clayton's Rivulet : near Hamilton, on the 

 River Forth ; near Mt. Lyell ; and in the small streams 

 in the vicinity of Brown's Plain. 



12. Andalusite (Anhydrous Silicate of Aluminium). 



Occurs in slightly rhombic, four-sided prisms imbedded 

 in rocks that have undergone contact metamorphism. It is 

 very rare and undefined. The locality is uncertain. The 

 variety chiastolite occurs sparingly imbedded in Silurian 

 slate, as radiating and interlaced prisms of small size. 



Locality : Near Zeehan. 



13. Andesite (Poly silicate of Aluminium, Sodium, and 



Galciutn). 



This is one of the varieties of triclinic felspar that are 

 intermediate between the species known as albite and 



