22 TIN DEPOSITS OF THE YORK REGION, ALASKA. [no. 229. 
Per cent. 
Manganous oxide (manganese, 0.424 per cent) 548 
Zinc oxide (zinc, 0.257 per cent) 320 
Nickel and cobalt oxides Traces. 
Silica 28. 52 
Alumina 33. 55 
Ferric oxide 8. 31 
Lime - 6. 75 
Magnesia 25 
Lithium oxide 09 
Potassium oxide 91 
Sodium oxide 36 
Water, carbonic acid, etc 6. 48 
Sulphuric oxide (sulphur, 0.04 per cent) 10 
The alumina, etc., may contain titanic acid. The magnesia and alka- 
lies require confirmatory determinations. 
Tin ore in the form of stannite or tin pyrites has been found on Tin 
Creek at the upper contact of the large granite area which has been 
described, and about half a mile below the cassiterite ledge. Speci- 
mens of mineralized granite were collected at this place, which, on 
examination in the laboratory of the Survey, are found to contain a 
small amount of tin in the form of stannite, together with other sul- 
phide minerals. A sample of this ore assayed by Mr. E. C. Sullivan 
contained 0.3 per cent tin. Mineralized granite of this character 
appears to cover a considerable area, but the ore is probably of little 
value, except as showing the distribution of tin through the granites 
of the region. 
In 1898 a party of disappointed prospectors, returning from Kotze- 
bue Sound, were shipwrecked a few miles east of the mouth of Lost 
River, and were obliged to camp at that point during the winter. A 
cabin built largely from wreckage of their schooner is still standing, 
and is known as the Kotzebue cabin. These prospectors probably 
first applied the name Lost River to this stream. 
In the succeeding summer a mining district was organized by sur- 
vivors of this expedition, with headquarters located on King River, 
which enters Bering Sea between Lost River and Cape York. The 
Lost River region was included at that time in the King River record- 
ing district. No discoveries of gold were made, however, and the 
region was abandoned by prospectors. In 1901 the writer, in company 
with Mr. D. C. Witherspoon, topographer, of the Geological Survey, 
made a hasty examination of Lost River, but did not discover any 
indications of tin ore. 
In the winter of 1902 prospectors again turned their attention to this 
region in the search for tin ore. Granite-porphyry dikes, which oc- 
cur in the limestones near the mouth of Lost River and also near King 
River, first attracted their attention, and many specimens of this 
material containing dark colored or smoky quartz phenocrysts, which 
