442, Transactions.— Geology. 
Mareasite (Radiate Iron Pyrites), Fe”.—This mineral, which 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’ Rep., 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’ Rep. N.Z. Ex., p. 486). 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 ‘p, occurs as small prismatic crystals in Moa bones from 
the N. E. Valley, Dunedin, where they were originally discovered by Dr. 
Hector (see Jurors’ Rep. N.Z. Ex., pp. 264, 436), and it has since been 
discovered in an earthy form imbedded in clay at Timaru; Pohangina River, 
Manawatu ; 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-+-7H, occurs at the Thames Goldfield, and also as @ Pro 
duct of decomposition in some of the coal mines. Its occurrence was first 
mentioned by Mr. Skey (Geol. Rep., 1870-71, p. 87), as occurring in @ 
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, Chloropheeite, and Green Earth, which are all hydrous silicates 
of iron, with other impurities, occur as fine earthy minerals, of a dull 
olive-green colour, filling cavities in the melaphyres of the Mount Somers, 
Rangitata, and Malvern Hills distriets. They were originally detected by 
Dr. Haast (see Jurors’ Rep. N.Z. Ex., p. 257). : 
