440 Transactions.—Geology. 
1865, pp. 264-436), but we have no specimen in the Museum. Professor 
Liversidge again mentions the occurrence of this mineral at Dunedin 
(Trans. N.Z. Inst., vol. x., p. 494), as well as a magnesian ironstone from 
the Clutha. 
Spherosiderite occurs as an accessory mineral in many of our volcanic 
and dyke rocks. Thus Dr. Hector mentions it as occurring in basalt 
(Jurors’ Rep. N.Z. Ex., pp. 264 and 436), and Dr. Haast mentions its 
occurrence in dyke rocks, and in the volcanic rocks of Banks Peninsula 
and the melaphyres of Mount Somers (Jurors’ Rep., p. 258; Geol. Rep., 
1873-74, p. 4, and Trans. N.Z. Inst., vol. xi., p. 504). It is generally 
found as small rhombohedral crystals, lining cavities in these rocks. 
Dendritic Iron markings are of very frequent occurrence in all the harder 
and jointed rocks, some of them being of exceeding beauty. They are 
frequently mistaken for fossil ferns, which they very much resemble at 
times. 
Ilmenite (Titanate of Iron).—This species includes several varieties due 
to the isomorphous characters of titanic and ferric oxides, so that the per- 
centage of titanic acid present varies very considerably in different speci- 
mens. It is of very common occurrence as an accessory mineral in the 
yoleanic rocks, where it occurs aS small rhombohedral crystals, affording 
triangular or pentagonal sections when cut, and it enters largely 
into ‘the composition of many of the ironsands of New Zealand, which 
surround so large a proportion of our coast. These ironsands are com- 
posed of a proportion of titanic iron, ranging from 2-4 per cent. to 742 
per cent. of the whole, mixed with Magnetite and Hematite in varying 
ons. : 
It is very difficult to group these in any definite order by the amount of 
titanic acid present, but it is noticeable that amongst those which occur on 
the southern beaches and also in the river beds the percentage is frequently 
"high, ranging from 40 to 74 per cent. of titanie iron, and these have been 
principally derived from the basaltic rocks of the district. 
On the other hand, the ironsands of the west coast of the South Island © 
are practically free from TiO, in many cases, while the well known Tara- 
naki ironsand only contains from 6 to 8 per cent. of titanic iron. There are, 
however, many ironsand deposits in Otago and Southland which contain © 
from 2 to 8 per cent. titanic iron only, so that it is impossible to assign 
special areas over which any pereeniage iia hold. Such, howover, is not 
the case if we seek the rocks from whi ‘ have derived, 
- for we there find thatthe basaltic rocks have asa ule yielded an 
