Mocks of the Hoivqua River. 45' 



In this rcMi'k muck recrystallisation under pressure has occurred. 

 Most of the augite has recrystallized as fibrous secondary horn- 

 blende, with light to dark green pleochroisni, and extinction angles- 

 ranging from 11° to 21°. The felspar has recrystallized to water 

 clear secondary felspar, "with enclosures of secondary hornblende- 

 needles. Ilmenite in large skeleton rhombohedra altered to leuco- 

 xene, is fairly abundant. Some interstitial secondary calcite is 

 present. The extensive recrystallization of the rock is no doubt 

 referable to its occurrence in a crushed zone, south of Fry's, and 

 it resembles some of the recrystallized diabases of Heathcote and" 

 Mt. William, near Lancefield, but is hardly so altered as the epidio- 

 rites of Ceres, near Geelong, since some relic structures in the form- 

 of original augite and felspar are still noticeable. 

 No. 18. — Diabase, south-east of No. 17. 



A. diabase which has suffered fairly complete recrystallization tO' 

 fibrous hornblende, and secondary water clear felspar. In the 

 process a considerable amount of granular and dusty magnetite has- 

 separated out. 



No. 22. — From main diabase mass. Lick Hole Creek, and east 

 of isolated crushed diabase mass. A relatively coarse-grained type- 

 with no signs of recrystallization under pressure. Coarse plates^ 

 of augite and cloudy felspar form the bulk of the rock, with 

 chlorite and clear felspar as secondary products. 



No. 25. — Soda rich diabase (analysed), Lick Hole Creek, one- 

 mile north of the Governor, and near the south-east end of the 

 main diabase mass. (Micro. Photo., Plate I., Fig. 1.) 



About 2-3rds of the rock consists of felspar in large and smalh 

 prismatic, quadrate or irregular crystals. Simply twinned and 

 untwinned crystals are abundant, and some show lamellar twin- 

 ning. The loAv refractive index, positive sign, and biaxial figure- 

 show that albite or albite-oligoclase predominates. All the felspars- 

 are clear, and some contain secondary hornblende and chlorite, 

 suggesting recrystallization. Some original augite remains, but 

 much is altered, either to normal hornblende or green pleochroic- 

 fibrous actinolite. Sphene, epidote and zoisite occur in granules. - 

 Brown clustei's of radiating biotite crystals occur, and some calcite, 

 a little quartz, and a few elongated prismsi of apatite are present. 

 The high albite content of the rock is confirmed by the chemicaf 

 analysis, but it is difficult to reconcile the relative abundance of 

 ferro-magnesian minerals with the strikingly low magnesia content 

 recorded in the analysis. 



