362 The N.Z. Journal of Science and Technology. [Nov. 
workings. Already a very considerable tonnage of excellent magnesite 
is disclosed in the workings, and there is promise of a large quantity of 
magnesite being obtained from this locality. 
“ The magnesite results from the decomposition of the basic rock, and 
its formation in the decomposed granitic rock results from the jointing 
and decomposed condition of the granitic rock ; therefore this deposit 
may be expected to continue as far down as alteration has taken place, 
but where the rocks are in their normal condition and not altered the 
magnesite will not be found. Further mining is required to ascertain 
to what depth the mineral continues. 
“ Much of the mineral consists of nodules that on breaking through 
are perfectly white and without any stain of iron. Other portions have 
a slight reddish colour from the presence of a small quantity of iron oxide, 
but this is no detriment in many cases. 
“ As to the uses of magnesite, it is largely used as lining for steel-furnaces 
and for basic fire-resisting bricks. Roasted and ground finely it makes 
the strongest cement known, and is used in this state or mixed with small 
fragments of wood for making floors, it having the remarkable quality 
of adhering to the wood. Owing to its comparative scarcity the mineral 
is a valuable one, and many fields for its use are opening up ; it is 
therefore important to have a supply within the State. Analysis of the 
purer portion gives the following result :— 
Insoluble siliceous material 
t , 
0-26 
Iron and alumina 
0-14 
Lime (CaO) 
Magnesia (MgO) 
Moisture (H 2 0) (at 110° C.) 
Moisture (H 2 0) (above 110° C.) 
Carbon dioxide (C0 2 ) 
0-07 
.. 48-05 
0-16 
• • j- 51-87 
Phosphorus pentoxide (P 2 0 5 ) 
Nil 
Chlorine (Cl) 
Trace 
Sulphates (S0 4 ) 
Nil 
• 
100-55 
The other report forwarded by Mr. Dickson is entitled “ The Redesdale 
Magnesite Deposits,” and was written by Mr. H. S. Whitelaw, Field 
Geologist. It bears the date 24th August, 1917. Mr. Whitelaw states 
that the occurrence of magnesite in the Redesdale district has been known 
since road-cuttings were first made in the Caliban-Campaspe River basalt 
plateau, forty years before, but only recently had any attempt to mine 
it been made. A Bendigo syndicate had forwarded to Melbourne firms 
30 tons of the material at a contract price of £2 2s. 6d. per ton, but one 
firm had refused delivery of a consignment owing to part being broken 
too small for its requirements and part being coated with clay, and in 
consequence mining had ceased. The clay, however, could easily have 
been removed by hosing. 
The deposit worked by the Bendigo syndicate is about two miles north 
of Redesdale. It consists of a vein 2 ft. to 4 ft. wide, which has been 
opened up for a chain in length and to a depth of 5 ft. to 15 ft. From 
Mr. Whitelaw’s description it may be inferred that the vein is apparently 
conformable to the bedding of the enclosing Ordovician slates, which pitched 
10° to the south and dipped 70° to the east. Parallel veins outcrop at 
intervals along Wedge Gully and southward for a quarter of a mile to the 
