^42 Transactions. — Geology. 



Marcasite (Radiate Iron Pyrites), Fe".— This mineral, wliich crystallizes 

 in the rhombic system, is of very frequent occurrence associated with our 

 brown coals. It generally occurs in radiate spherical or cockscomb-like 

 groups, and from its proneness to decomposition has doubtless been the 

 cause of many of the subterranean fires which have been of such frequent 

 occurrence in our Otago collieries. It also occurs in many of the tertiary 

 clays, and specimens were exhibited^from Canterbury by Dr. Haast in the 

 New Zealand Exhibition of 1865 (see Jurors' Eep., p. 257). 



Pyrrhotine, Fe'. — The occurrence of this mineral has been previously 

 mentioned under the nickel ores. 



Glauconite — which is a hydrous silicate of the protoxide of iron and 

 potash, is of frequent occurrence in certain schists, and also in the green- 

 sand series (Hector, Jurors' Eep. N.Z. Ex., p. 436). It occurs as rounded 

 grains in several of the younger secondary beds, but is more markedly 

 developed in the Weka Pass calcareous greensand series than any other, 

 but in this formation has a somewhat wide distribution in the colony. 



Vivianite, Fe ^, occurs as small prismatic crystals in Moa bones from 

 the N. E. Valley, Dunedin, where they were originally discovered by Dr. 

 Hector (see Jurors' Eep. N.Z. Ex., pp. 264, 436), and it has since been 

 discovered in an earthy form imbedded in clay at Timaru ; Pohangina Eiver, 

 Manawatti ; Port Chalmers ; and Taranaki. The crystallized specimens are 

 of a deep indigo blue colour, and the earthy varieties are all bright cobalt blue. 



Copperas, FeS-f 7H, occurs at the Thames Goldfield, and also as a pro- 

 duct of decomposition in some of the coal mines. Its occurrence was first 

 mentioned by Mr. Skey (Geol. Eep., 1870-71, p. 87), as occurring in a 

 crystallized form in the Long Drive Claim at the Thames, where it is found 

 in all the old drives and workings where the enclosing rock is, or has been, 

 pyritous, and the presence of this mineral as pointed out by Mr. Skey 

 exercises a very prejudicial effect upon the quicksilver, causing it to flour. 

 The specimens in the Museum are of a bright mountain-green colour ; they 

 are translucent and vitreous, and though crystalline in character do not 

 occur in properly formed crystals. 



Delessite, Chloropliceite, and Green Earth, which are all hydrous silicates 

 of iron, with other impurities, occur as fine earthy minerals, of a duU 

 olive-green colour, filling cavities in the melaphyres of the Mount Somers, 

 Eangitata, and Malvern HiUs districts. They were originally detected by 

 Dr. Haast (see Jurors' Eep. N.Z. Ex., p. 257). 



Copper. 



The occurrence of copper in New Zealand has been known since 1842, 

 when the Kawau Mine commenced work on a lode of copper pyrites, and 

 since then it has been found in various forms throughout New Zealand. 



