BY W. F. PETTERD, C.M.Z.S. 73 



1*27. Franklinite (Oxides of Iron, Manganese, and 



Zinc). 



A mineral with metallic lustre, dark — almost black — 

 colour, and characteristic reddish-brown streak. Obtained 

 in amorphous and crystalline bunches intermixed with 

 galena, mainly at the 200-feet level, Silver Queen Mine, 

 Zeehan. 



128. Freibergite (Argentiferous Tetrahedrite). 



Silver ' fahl ' ore is usually of a much darker colour than 

 the normal substance, and is, moreover, more liable to 

 decomposition. At the Hercules Mine comparatively small 

 pockets of this ore have been met with, which sometimes 

 assayed up to nearly 3000 oz. of silver per ton, and at 

 several of the Dundas fahl ore mines it has been obtained 

 assaying high in silver contents, notably at the Ring Valley 

 and Curtin-Davis Mines. 



129. Gahnite ( Aluminate of Zinc). 



Also known as zinc spinel. Occurs as small octahedra, 

 of a pale-green colour, imbedded in a soft kaolinic matrix, 

 at Mt. Bischoflf. 



130. Fluorite (Fluoride of Calcium). 



This is also known under the names of fluor, fluorspar, 

 and to the Cornish miners as " cann." It crystallises in the 

 isometric system, and is commonly in extremely well-defined 

 cubes of perfect regularity. Fluor is so generally con- 

 sidered a fairly constant associate, and to be intimately 

 connected with the occurrence, of cassifcerite, as a tin-carry- 

 ing fluoric companion, that the comparative rarity of the 

 mineral at the majority of the tin-mining districts of the 

 island is very noticeable. Many of the so-called tin-bear- 

 ing lodes are totally destitute of the mineral, and its pres- 

 ence in a pronounced form is exceptional. It is almost 

 unknown at t'he silver-lead mines, and is, in fact, of 

 somewhat rare occurrence under any conditions. Since 

 fluorine is believed to be an important factor in the forma- 

 tion of tinstone as a carrier of the metal, it is remarkable 

 how limited is the occurrence of this mineral throughout 

 the island. It perhaps shows more diversity and variation 

 in colouration than any other known mineral, varying from 

 perfectly water-clear to many shades of green and purple, 

 and even that of a distinct pink tint is not unknown. 

 Colourless fluor when clear and pellucid is a rarity, and is 



