BY LOFTUS HILLS, M.B.E., MSC. 139 



(6). The Tin Deposits or the Stanley River District. 

 These have been described in detail by L. L. Waterhouse 

 in Bulletin 15 of the Geological Survey, following upon pre- 

 vious work by G. A. Waller. 



The deposits are mainly of the Quartz-Tourmaline-Cas- 

 siterite type and what are termed Stanniferous Contact 

 Metamorphic Deposits. These are both described in detail in 

 regard to structural features, composition, and paragenesis. 

 It is important to note that it has been demonstrated by 

 Waterhouse that the cassiterite in the contact metamorphic 

 deposits is later than the contact metamorphic minerals. The 

 origin of the ore-bearing solutions is shown to be the Epi- 

 Silurian granitic plutonics strongly developed in the field. 



Sufficient evidence, however, is not available to establish 

 the definite relation between the two types of tin deposits, 

 nor between these and the zinc and lead veins. 



(7). The Heemskirk Tin Deposits. 



G. A. Waller described these deposits in considerable 

 detail in 1902, and L. L. Waterhouse carried out a more 

 comprehensive survey in 1914. The description of this field 

 is contained in Bulletin No. 21 of the Geological Survey, and 

 the description of the ore deposits is presented in meticulous 

 detail. 



The tin deposits are classified into six types:— 



(1) Quartz-Tourmaline-Cassiterite Veins; 



(2) Quartz-Quartzose Deposits; 



(3) Pyritic Cassiterite Deposits; 



(4) Pinitoid Veins; 



(5) Greisen Veins; 



(6) Pipe Formations. 



The structural features, composition, and paragenesis 

 of all of these types are described in detail. In addition, 

 contact metamorphic deposits are described, as well as zinc 

 and lead deposits and nickel ores. It is shown that certain 

 of the zinc and lead deposits are variants of certain of the 

 tin veins, and zonal precipitation is given as the explanation 

 of the change in character with increasing distance from the 

 magmatic hearth. The contact metamorphic deposits pre- 

 ceded the tin deposition. 



The whole of the ore deposits in the field are shown to 

 be genetically connected vvith the Epi-Silurian plutonics. 



