152 Notes on the Area of Intrusive Bocks at Dargo. 



It may be well at this place to draw a distinction between 

 the auriferous quartz veins and other veins of quartz which 

 are found at or near the contacts, and which have, in three 

 instances within my knowledge in Gippsland, been fruitlessly 

 prospected for gold. 



The class of quartz veins to which I now refer is not, so 

 far as I have observed, auriferous, or even ore-bearing. At 

 any rate, no gold has been found in them by any of the 

 ordinary methods of. examination.* They are either of 

 quartz only or of quartz together with one or more charac- 

 teristic minerals. In the neighbourhood of Dargo I have 

 observed quartz veins of small size of this kind near or at 

 the contacts composed of quartz with small schorl crystals. 

 Far more clearly, however, is the distinction between the 

 two classes of quartz veins to be seen near Omeo. The 

 auriferous reefs which have been found and partly worked 

 there are essentially of the character of those at Dargo, 

 being veins of quartz mineralised by arsenical and ordinary 

 pyrites and galena with gold^ at the contact of quartz mica 

 diorites with the regionally-metamorphosed schists. The 

 features which I desire to bring out into view are there much 

 more marked than at Dargo, and I therefore take my illus- 

 trations from them. Besides these auriferous quartz lodes, 

 there are also throughout the neighbourhood of Omeo 

 numerous veins, and even large masses of quartz, which fill 

 fissures in or are interfoliated with the metamorphic schists, 

 or traverse parts of the plutonic rocks. The quartz of these 

 veins is in places milky in colour, and in others translucent 

 and extremely crystalline. In addition to these veins of 

 quartz only there are others of the same class which contain 

 schorl or cleavable masses of felspar, or muscovite mica, or 

 two or all of them together in varying proportions, so that 

 veins may be extremely quartzose with but little proportion 

 of minerals, or may be so charged with them as to become a 

 variety of pegmatite. 



A study of the veins composed of quartz alone, or of 

 quartz with schorl, brings out certain features which are of 

 moment in this consideration. The prismatic crystals of 

 schorl are often penetrated by thin films of quartz, or have 

 been broken across, the parts being removed from each other 

 and separated by the silica. If such crystals are extracted, it is 

 found that the quartz has perfectly moulded their most 



* I now refer only to the Dargo and Omeo districts. 



