Marshall. — Additions io List of New Zealand Minerals. 105 



The photographs taken by Mr. Browne at Easter, 1907, and by Mr. 

 Cockayne this year, do not show any material change as a result of the rather 

 violent activity that was in progress when the photograph (Plate VI) was 

 taken. It appears, however, that the extension of the deep cavity westward 

 and northward has been continued to a slight extent. In all my visits 

 to the crater the escape of steam from it has been much more voluminous 

 than is shown in the photograph of the crater taken by Mr. Cockayne.* 



There is one point about which I am not certain. A small mud-crater 

 is to- be seen on the east side of the big explosion-cavity. When it was 

 formed I do not know; it certainly was not there in 1891. It may have 

 been formed at the same time that the explosion-cavity was blown out, 

 though I have no note of its presence in 1893. 



To sum up : — 



1. The form of the crater appears to have been very different in 1839 

 and 1852 from its present shape. 



2. In 1891 the floor was level, except where the north-west crater was 

 situated, which was then the most active spot. 



3. In 1893 the north-west crater was less active, and the explosion- 

 cavity was of small diameter near the middle of the crater, and was steaming 

 vigorously. 



4. Since that time the explosion-cavity has extended westwards and 

 northwards, and the activity of the north-west crater has dwindled. 



5. No escape of lava has occurred within historic times. 



6. The main-crater walls have not changed since 1891. 



EXPLANATION OF PLATES V-VII. 

 Plate V. 

 Fig. L Crater of Ngauruhoe in 1891. 

 Fig. 2. The same in 1907. 

 Fig. 3. Tiie same in 1906. 



Plate VI. 

 U])])er part of cone of Ngauruhoe, at 8 a.m., 14th Jilarfh, 1907. Photo taken from the 

 .south-east ; distance, five miles. 



Pl.\te VI ^ 

 Highest point of crater-wall of Ngauruhoe — the south-east side. 



Art. XX. — Additions to the List of New Zealand Minerals. 

 By Dr. P. Marshall, M.A., D.Sc, F.C.S., University of Otago. 



\limd before the Oltijo Instiiute, Wlh Xorei/iber, 1908.] 



Ix the year 1890 Sir .lames Hector compiled a list of New Zealand minerals 

 for inclusion in the " Transactions of the Australasian Association for the 

 Advancement of Science " (vol. ii, 1890). Since that time a large number 

 of papers have been written by a variety of authors on New Zealand geology. 

 In these papers inauy references have been made to minerals that are not 

 included in Sir James Hector's list. In the present paper these references 



"Tongariro National P.ak" : L. Cockayne. Parliamentary paper C.-ll, 1908. 



