THE NONMETALLIC MINEKALS. 457 



sandstone near Kuji, Japan. 1 It is reported as being of inferior quality, 

 opaque, cloudy, and much fissured. It is, however, mined and shipped 

 to Tokio, where it is presumably worked up into small ornaments. 



The so-called Burmese amber, or Burmite from the Hukong Valley, 

 is reported as occurring in a soft blue clay, probably of Lower Miocene 

 age, and in lumps not exceeding the size of a man's hand. 



GUM COPAL. The name copal or gum copal is made to cover, com- 

 mercially, a somewhat variable series of resins more or less fossilized 

 and found for the most part buried in the sands in tropical and sub- 

 tropical regions. They are in general amber-like or resin-like in 

 appearance, of a hardness inferior to that of true amber, of a light yellow 

 to brown color, brilliant glass-like luster, transparent to translucent, 

 and have a conchoidal fracture. When cold they are brittle and can 

 be readily crushed to powder, but possess a slight amount of elasticity. 

 When rubbed on cloth they become electric and emit a peculiar resin- 

 ous odor. The specific gravity varies from 1 to 1.10. When heated 

 the material softens, swells up, and bubbles, finall} 7 melting, remain- 

 ing liquid until carbonized. It burns with a yellow smok} 7 flame; is 

 partially soluble in alcohol, wholly so in ether, and also in turpentine 

 on prolonged digestion. The so-called Kauri gum is a light amber- 

 colored variety from the Dammara Australia, a living coniferous tree 

 of New Zealand (Specimens Nos. 62468, 62469, U.S.N.M.). The prin- 

 cipal source is the northern portion of the Auckland provincial district 

 which has exported since 1863 (and up to 1897) some 134,630 tons of 

 gum valued at 5,394,687, the product for 1890 being 7,438 tons 

 valued at 378,563. 



The gum-digging industry is one that gives employment to both 

 Europeans and natives. 8 The gum is found but a short distance below 

 the surface and is dug with the aid of a few implements, the entire 

 outfit often consisting of a steel prod, a spade, and knife and haver- 

 sack. With the copal is often found the more amber-like resin ambrite, 

 which has a slightly greater hardness (2), a specific gravity of 1.034, a 

 yellowish gray to reddish color and which yields on analysis carbon, 

 76.88; hydrogen, 10.54 per cent, and oxygen, 12.77 per cent. It 

 becomes strongly electric by friction and is insoluble in alcohol, ether, 

 chloroform, benzine, or turpentine and burns with yellow, smoking 

 flame. Quite similar to the kauri gum is the copal of the African 

 coasts. According to Dr. F. Welwitsch 3 gum of the west coast and 

 probably all the gum resin exported under this name from tropical 

 Africa is to be regarded as a "fossil resin produced by trees which, 



transactions of the American Institute of Mining Engineers, V, 1876, p. 265. 



2 Report of the Mining Industry of New Zealand for 1888. In the report for 1887 

 it is stated that "according to the last census" the number of persons employed in 

 the occupation of gum digging was 1,283. 



3 Journal of the Linnaean Society of London, Botany, IX, 1866, p. 287. 



