428 Transactions. —Geology. 
One of these specimens shows the tufanite (pyritous propylite) forming 
one side of the vugh or cavity, on which a layer about 2-inclt thick of 
fibrous crystalline quartz has been formed. At the base of the specimen a 
quartz leader about 8 inches wide and crystallized in small vughs near the 
centre is inserted through the lining of the cavity, which is formed by the 
junction of two small veins. This leader is traversed by small strings of 
crystals of Mispickel or Leucopyrite, and on the internal quartz coating of 
the cavity Calcite has crystallized at places in large rhombohedral forms, 
and at others the arsenic has been deposited in reniform masses. 
On the faces of the Calcite crystals small globular patches of arsenic 
have formed, and stalagmitic incrustations of Calcite, with alternate layers 
of arsenic, have been built up on these, forming fine reniform masses. 
At one point, near the top of the specimen, minute quartz erystals can be 
seen, also Calcite forming hollow pseudomorphs of quartz, all the cavities 
of which are filled with the most beautiful filaments of gold; a few crystals 
of Mispickel are here visible. 
The other specimen is of a massive reniform character, and is deposited 
on the quartz lining of the vugh without the interposition of Calcite as in 
the first specimen. 
Mispickel, Fe'4+-FeAs, or arsenical iron pyrites, is by no means un- 
common in New Zealand. It is mentioned by Dr. Hector, (Jurors’ Rep. 
N.Z. Ex., pp. 265, 486), as occurring in magnesian felstone and diorite 
in Milford Sound, and also in alluvial drifts at Waipori and elsewhere, 
and is again referred to by Professor Liversidge, in his description ¢ 
the minerals of the Otago Museum (Trans. N.Z. Inst. vol. x., p. 502). 
page 257 of the Jurors’ Reports, above cited, this mineral is mentioned in 
Dr. Haast’s collection as occurring in diorite at the Malvern Hills. 
Specimens have been collected by Mr. McKay from the Buckleburn, 
on Wakatipu Lake, as fine crystals imbedded in chlorite schists, and, 8 
previously mentioned, it occurs in the auriferous leaders of the Kapanga 
mine, and is found in most other auriferous reefs. Specimens brought by 
Dr. Hector from Langdon’s lower reef, near Greymouth, proved to be highly 
- auriferous, the assay of the sample showing 69 ozs. 3 dwts. 12 grs. of gold, 
and 2 ozs. 9 dwts. 19 gers. silver, to the ton, a considerable proportion of 
it, however, being in a free state. 
I collected specimens of the same mineral ha the Perseverance mine, 
Collingwood, where it occurs in very characteristic rhombic orystels,. ina 
white granular quartz, but contains very little gold. : 
_ As a rule this class of pyrites is the most highly auriferous, although 
a at times gold alo ounes. easly ie fo mene coment SEE 
