274 N. R. Junncr: 



eilicification lias taken i^lace is evident from the silica added to some 

 of the quartz phenocrysts. The rock is a rhyolite tnff. 



Section No. HSl, from near H4, is again composed ahnost entirely 

 of rhyolitic debris. — Rectangular sections of muscovite, secondary 

 after biotite, are numerous and clear, simply twinned laths of acid 

 plagioclase are not uncommon. Microperthitic orthoclase occurs as 

 fragments of crystals, much corroded and greatly sericitised in 

 places. The matrix is chiefly finely granular silica, chalcedony, 

 and sericitised felspar. Certain colourless isotropic cubes, of a 

 mineral having a refractive index much less than that of the 

 ground mass, are undoubtedly fluorite. 



Section No. H9, track to Malory's falls, is made up of lapilli of 

 andesitic and rhyolitic rocks and fragments of chlorite, secondary 

 after biotite, quartz, plagiolcase, biotite and highly sericitised 

 orthoclase in a matrix composed chiefly of quartz and sericitised 

 felspar. Abundant leucoxene and zircon occur scattered through 

 ■the section. Microperthitic orthoclase is almost entirely absent. 

 One or tAvo fragments of garnet are also present. 



Section No. H39, immediately west of the Blacks' SjDur road, on 

 the track to Malory's falls. — Fluorite cubes are again present in this 

 section. The rock is a normal rhyolite tuff. 



M.M.B.W. pipe line to Badger Greek Weir, S.S.W . of Mount 

 Riddell. — Ashes, tuffs with fine lapilli, and coarse agglomerates are 

 all present in the rocks from this locality. The agglomerate pebbles 

 are usually small, being rarely more than three inches in diameter, 

 and are mostly sub-angular in shape. They consist almost entirely 

 of a yellowish-green, aphanitic, pyritised rock resembling in hand 

 specimen the Diamond creek dyke rock. No signs of bedding are 

 visible in any of the tuffs. They are frequently honeycombed, and 

 secondary carbonates, sericite and pyrites have been developed in 

 them. 



Specimen No. H88, pebble in agglomerate, S.S.W. of Mount Rid- 

 dell, is a leucocratic, aphanitic rock showing "minute grains of 

 quartz, felspar and a little pyrite in hand specimen. Micro- 

 scopically, it consists of phenocrysts of altered felspar, quartz and 

 a little chloritised femic mineial, in a ground mass of quartz, 

 felspar laths and occasional ilmenite. Carbonates, sericite. Lhlorite, 

 rutile and leucoxene are secondary minerals. Veinlets of quartz 

 and carbonates traverse the rock. The felspar phenocrysts are pre- 

 dominantly orthoclase; highly sericitised in general and often 

 carbonated. The plagioclase phencrysts are of albite or albite- 

 oligoclase, and are not zoned. The grains of quartz are pellucid as 



