484 Transactions. — Geology. 



some chromous oxide at least is present, but I have not yet 

 satisfactorily estimated what quantity of it is present. 



The analysis of the other hartzbergites given above shows 

 that this rock, except for the magnesite, is a very pure 

 sample. Its composition seems to be, — 



Total ... 98-93 



The present occuiTence is evidently closely connected with 

 that at Red Hill, whence the rock (analysis B) came, and 

 dunite has also been reported from the same district, as well 

 as serpentine and bowenite. The relations of these rocks to 

 surrounding deposits, as well as their age, still remain a pro- 

 blem, though the Geological Survey has referred them with 

 some confidence to the Devonian period. The high specific 

 gravity — 3-2 in this case, and 3 - 35 in some of the Red Hill 

 rocks — shows that these rocks are properly resident at an 

 enormous depth from the surface, so some specially potent 

 tectonic disturbance, whose nature will, we hope, be after- 

 wards unravelled by New Zealand geologists, must have been 

 necessary to bring these rocks to the earth's surface. It is 

 perhaps of interest to add that no trace of awaruite was 

 found in the rocks or sands of the Milford Sound magnesian 

 rock district, and only a faint trace of Ni could be obtained 

 chemically. 



', JfornbUside, some. JfmKb&rqLte, ^arcres LouZoUr- 



GrcLnttZXe. JcA^t 



rite, U, aJ-cres t/OVoCcLer 



-Ji&OLcJi/ JiouJsoL&r-s ^e^ccA. 



£=>— w. 



Section one mile and a half long of Anita Bay, south side of Milford 



Sound, near entrance. 



EXPLANATION OF PLATE XLVII. 



Fig. 1. Dunite. Shows cataclastic structure of rock. A large crystal 

 of chromito is in the centre of the irregularly shaped broken 

 fragment of olivine crystals. 



Fig. 2. Hartzbergite. A large plate of enstatite encloses pieces of iron 

 ore and rounded grains of olivine showing a distinct pcecilitic 

 structure. No magnesite is shown in the photograph. 



