122 KEMP'S ORE DEPOSITS. 



exhibiting more perfectly the peculiar lenticular shape characteris- 

 tic of magnetite, and to this class are to be referred the greater 

 number of smaller bodies (Hammondville). They pinch and swell, 

 roll and fold and feather out, and often come off sharply from the 

 walls. They frequently follow and overlap one another like shin- 

 gles, the second one succeeding the first in the footwall. They are 

 not infrequently cut by trap dikes and are thrown by these and by 

 normal faults. At Hammondville small gulches seem to cut off 

 the ore, and are probably due to faults. Other deposits are of 

 enormous size, as at Mineville (200 to 300 feet clear ore between 

 the walls), and their relations are less clear. They may be large 

 lenses doubled over in a sigmoidfold. The Champlain magnetite is 

 quite notably granular as contrasted with New Jersey, which tend& 

 rather more to break in prisms. 



2.03.04. C. E. Hall has divided the metamorphic rocks of the 

 Adirondacks into the (a) Lower Laurentian Magnetite Iron Ore 

 series, containing the most important ore beds, (b) The Lauren- 

 tian Sulphur Ore Series, (c) The Limestones and the Labrador or 

 Upper Laurentian, with Titaniferous Iron Ores, (c) is thought to 

 be certainly later than (a), but the relations of (b) are uncertain. 

 T. S. Hunt also states that the titaniferous ores are associated with 

 the Labradorite series or Norian, which he places as of later age 

 than the gneisses with the good ore. 



Commercially the ores are divided into (1) ores high in phos- 

 phorus but low in sulphur ; (2) ores low in both phosphorus and 

 sulphur; (3) pyritous ores; (4) titaniferous ores (Tenth Census, 

 Vol. XV.). Under class (4) come numerous beds which are worth- 

 less, but which if the titanium could be neutralized would be very 

 valuable (Lake Henderson ; see Addenda.). Mineville is by far 

 the most productive region. It ships 400,000 to 500,000 tons yearly. 

 Chateaugay and Hammondville are next. The Arnold mines pro- 

 duce some, while the Palmer Hill mines with the decline of the 

 bloomaries have gradually ceased. The mines on the west side of 

 the mountains are less important. They afford, so far as developed, 

 a low grade of ore, that, however, with the improvements in mag- 

 netic concentration, seems to promise well. The largest openings 

 are at Jayville and Little River. 



There are numerous magnetite deposits in Canada of analogous 

 geological relations, but they are often highly titaniferous. 1 



1 L. C. Beck, Mineralogy of New York, Part I., pp. 1-38. J. Birkin- 



