TBANSACTIONS OF SECTION C. 153 



The prisms occur in diverging clusters, the largest in the 

 School collection being 4in. long and lin. in diameter. 



Pearl-spar. — This mineral occurs in fine rhombohedral 

 crystals at the Occidental Mine, situated on the western face 

 of Una Hill, Thames district. It is found as a narrow layer 

 in the centre of a quartz leader running into the main lode, 

 which is enclosed in a soft yellowish- white or grey even- 

 grained tufaceous sandstone. 



Epsoviite. — This mineral is comparatively abundant in the 

 old workings of the Waiotahi and Caledonian Mines, at the 

 Thames Goldfield. It occurs as a fine fibrous efflorescence. 

 The fibres are often over a foot in length, and possess a silky 

 lustre, and pure- white colour. Eeadily soluble in cold water. 



ChalcantJdte. — This mineral occurs as stalactitic masses in 

 the old levels of the Caledonian Mine. It has a deep-blue 

 colour and sour taste. Specimens of this mineral were brought 

 from the Champion Copper-mine, Aniseed Valley, Nelson, by 

 Sir James Hector in 



3. On Mount Cook Glacicr-2Iotion. 



By J. H. Baker, Commissioner of Crown Lands, Christ- 

 church. 



Plate XVII. 



In the year 1887, whilst on my first visit to the Mount Cook 

 glaciers, it struck me that the terminal face of the Mueller 

 Glacier occupied a position different from that assigned to it on 

 the map of the explorations of the late Sir Julius von Haast 

 made in 1862, it having evidently materially receded : unfor- 

 tunately the plan is on so small a scale — viz., four miles to an 

 inch — that no absolute data can be obtained from it to show 

 how much lower a position the terminal face then occupied than 

 that where we find it twenty-seven years later. Therefore, 

 when having the present topographical survey made, — which 

 was necessary to enable an accurate plan to be prepared show- 

 ing the position and extent of the Mount Cook glaciers, — I 

 determined to leave such permanent marks at the terminal face 

 of each of the glaciers that geologists who may hereafter ex- 

 amine them may have some reliable fixed points from which 

 to decide what changes have taken place between the date of 

 the survey referred to and that of their visit. Similarly, a 

 thought that it might be of some advantage to future observers 

 to know at what rate the glaciers were travelling at a given 

 spot, and on a given time and date, led me to instruct the 

 surveyor, when making his survey of the Hooker Glacier, to 



