Brarr.—On the Building Materials of Otago. 133 
though at opposite sides of the globe, their composition is practically the 
same. 
Metamorphic Rocks. 
The second class of hardstones, forming the metamorphic rocks, is com- 
paratively useless as a building material; a few of the connecting links 
between them and granite, being of a crystalline texture, might be utilised ; 
but, as gneiss proper, and the harder kinds of schist, are composed of the 
granitic constituents in a stratified form, they will neither break nor cut 
across the grain, consequently can only be used in the roughest work. 
There are several crystalline stones of the metamorphic formations of 
Otago that seem suitable for ornamental purposes. 
Granulite, of a light grey colour and fine grain, has been found at 
Breaksea Sound. Syenitic gneiss, of a grey flaky appearance, exists at 
«Connecting Arm,” and brownish gneiss at Anchor Harbour. These all 
appear capable of being dressed or polished into columns or slabs for monu- 
mental purposes. 
The slates in this series of rocks should yield paving stone. It is re- 
ported that such exists at Chalky Inlet, on the West Coast ; but I have no 
particulars regarding them. 
Voleanie and Trap Locks. 
It is from this class that the principal supply of hardstone is at present 
obtained, therefore the fullest information on its products and their proper- 
ties is of the utmost importance. So far as varieties are concerned, it is 
quite impossible to give even an indication of their extent. Although the 
area occupied by these rocks is comparatively limited, the building stones 
they yield are simply confusing in their profuseness. They comprise every 
texture and colour, from the black basalt that yields to nothing softer than 
diamond, to white tuffa, that can be sliced with a pocket-knife. Generally 
all compact stones of volcanic origin are durable, and being unstratified, 
there is no danger in using them in any position. As already stated, erup- 
tive rocks are found in several localities in the Province; but, so far as Iam 
aware, the Peninsula, and the district between Otago Harbour and Blueskin 
Bay, are the only places that produce the Trachytes, Breccias, Phonolites, 
and other stone of so varied a character. There are few rocks of economic 
value outside this area, except the ordinary blue and greenstones. 
Commencing with the hardest, we have black basalt and basaltic con- 
glomerates at the Bluff, Dog Island, Purakanui, Tairoa Heads, and various 
other places on the Peninsula, so hard that more steel than stone is removed 
in dressing them. They are, therefore, comparatively useless as building 
material, and I shall not consider them further. 
