422 Transactions. — Geology. 



The ore is found : — 



1. Massive crystalline. — In bands of a black crystalline character, varying 

 in its degrees of coarseness, and in some cases showing distinct planes of 

 the octahedron when fractured. No perfect crystals have as yet been 

 found. As a rule the crystalline bands have hitherto proved less continuous 

 in their character than those next to be described. 



2. Massive amorphous. — In bands of a brownish-black colour, and afford- 

 ing a brown streak. It is softer than the last-mentioned variety, and as a 

 rule occurs in larger and better-defined bands of ore, which also appear to 

 be more continuous both in length and depth. It is not so valuable an ore 

 as the massive crystalline variety, but, on account of its greater extension, 

 would probably receive a greater share of attention should works be under- 

 taken for its extraction. 



3. Crystalline disseminated. — A very interesting example of this ore 

 occurs on Little Ben Nevis, consisting of small segregations of chromite 

 evenly distributed through a pale-green serpentinous rock. The segrega- 

 tions are from ^ inch to ^ inch diameter, and are spotted through the rock 

 with great regularity, giving it the appearance of a conglomerate. When 

 found under these conditions the chromite corresponds in physical characters 

 with the massive crystalline variety previously described, and the ore- 

 bearing rocks appear to run in belts much the same as the regular ore 

 bands do, and follow approximately the same course. The surrounding 

 rock being soft, a mechanical means of separation for the ore so as to 

 increase the percentage of chromic acid should be simple. 



4. Gramdar disseminated. — In this character Chromite occurs as a con- 

 stituent of the rock Dunite, described by Professor Hochstetter (" New 

 Zealand," 1863, p. 474, Eng. Ed.), as follows : — " It consists of a very 

 peculiar kind of rock, of a yellowish-green colour when recently broken but 

 turning a rusty-brown on the surface when decomposing. The mass of 

 the rock is Olivine, containing fine black grains of chromate of iron inter- 

 spersed ; it is distinguished from serpentine, for which it was formerly taken, 

 especially by its great hardness and its crystaUine structure. I have called 

 it Dunite." These rocks occur in bands, which almost resemble dykes, and 

 which are, perhaps, better developed in the Dun Mountain than elsewhere 

 The quantity of Chromite which occurs in the rock is extremely variable 

 from a few dispersed grains to sufficient to form more than half of the 

 mass ; and specimens have yielded as much as 44-75 %' ^^a Os- 



This ore occurs as a 10-foot band in the Dun Mountain Company's 

 lease, and in the Eoding Eiver Company's ground a similar band is over 15 

 feet in width, and has been opened on vertically for 300 or 400 feet. The 



