BY W. F. PETTERD, C.M.Z.S. 91 



micro-crystalline grains, or may be massive. The pure 

 unaltered substance is commonly some shade of bluish- 

 groen or pale-blue, and is translucent. It occurs sparingly 

 as micro-crystals in the fayalite-melilibe basalt of One Tree 

 Point, near Hobart, and pseudomorphed to limonite in the 

 haiiyne-trachyte of Port Cygnet. 



149. Hematite (Peroxide of Iron). 



The native ferric oxide, which is so widely known as 

 hematite, usually occurs massive in this island, and is 

 almost unknown in a well-crystallised form. It is at once 

 one of the most abundant and widely diffused minerals 

 occurring in the northern and north-western portions of 

 the State. It crystallises in the rhombohedral system. 

 The crystals are usually in the form known as '' specular 

 iron." They have almost invariably a highly splendent 

 lustre, which characteristic is strongly noticeable with 

 much of the flakey material occurring in association with 

 the massive ore at the Penguin, and in a more limited 

 degree as regards quantity with that associated with wol- 

 lastonite near Rocky Cape (N.W. Coast), where it is in 

 irregular crystalline scales superimposed upon each other. 

 The same applies to other occurrences, from which habit 

 originates the universal application of the term " mica- 

 ceous iron ore." In occurrence hematite is commonly 

 associated with the hydrated oxides goethite and limonite. 

 These species usually form portions of the surface-outcrop, 

 which at times passes, by the admixture of alumina or 

 magnesia, into a soft ochre. It may sometimes be derived 

 from the hydrates by the removal of water, but the oppo- 

 site alteration by the hydration of the red-ore is in all 

 probability much more frequent. When occurring in 

 quantity its usual habit is in irregular deposits, often in 

 the planes of sedimentary rock bedding. It is at times 

 more or less siliceous; crystals of quartz are not infre- 

 quently closely intermixed, and occasionally line the 

 interior of cavities, or are gathered together in patches 

 or bunches. The views which have been advanced from 

 time to time to explain the origin and distribution of this 

 substance are varied to a degree. The origin of the ore 

 itself is one thing, and the origin of the deposit another ; 

 so that, singly or combined, there is presented a subject 

 which affords argument for a variety of hypotheses. 

 Doubtless each separate locality affords local peculiarities 

 which are characteristic of itself, and would lend support 

 to a given line of argument. It is the opinion 

 of many authorities, confirmed by local observation, 

 that in a vast number of cases the hematite masses 



