446 REPOET OF NATIONAL MUSEUM, 1899. 



in the AVest Indies. The material is described^ as a very pure hydro- 

 carbon of a black color, hioh luster, and with a bright conchoidal fracture. 

 It is brittle, and so friable that it can he ground to powder between 

 the thumb and fingers. (Specimen No. 53539, U.S.N.M.) It occurs in 

 seams or veins, varying from one-fourth of an inch to 30 feet in thick- 

 ness, cutting the country rock, which is an argillite or shale, at all 

 angles with the horizon and with a general NNE strike. In places 

 the bituminous matter has saturated the entire rock in the neighbor- 

 hood of the veins, producing a shale from which as much as 37 gallons 

 a ton of petroleum has been obtained by destructive distillation. Thus 

 far the greatest development is along a vein 200 feet in length, 100 

 feet in depth, and from 8 to 9 feet in width. One vein, which has 

 been explored to a depth of 200 feet, is stated to have dwindled down 

 to a width of 6 feet, though 30 feet wide at the surface. 



Uses. — Like gilsonite, the material is used for making varnishes, 

 insulating electric wires, etc., bringing the price of this mineral, from 

 $5 to $10 a ton, according to quality and freedom from impurities. 



Elaterite; Mineral Caoutchouc. — This is the name given to a 

 soft and elastic variety of bitumen much resembling pure India rubber. 

 It is easily compressible in the fingers, to which it adheres slighth% 

 of a brownish color, and of a specific gravity varying from 0.905 to 

 1.00. It has been described from mines in Derbyshire and elsewhere 

 in England (Specimens Nos. 63848, 68001, U.S.N.M.), but so far as 

 the writer is aware is of no connnercial value. Its composition, so far 

 as determined, is carbon 85.47 per cent, hydrogen 13.28 per cent. 



WuRTZiLLiTE. — The name ivurtzillite has been given by Prof. W. P. 

 Blake to a hydrocarbon very similar in appearance to the uintaite 

 (described on page 450), but differing in physical and chemical properties. 

 It is described as a fine l)lack solid, amorphous in structure, brittle when 

 cold, breaking with a conchoidal fracture, but when warm tough and 

 elastic, its elasticity being best compared with that of mica. If bent 

 too quickly it snaps like glass. It cuts like horn, has a hardness be- 

 tween 2 and 3, a specific gravity of 1.03, gives a brown streak, and in 

 very thin flakes, shows a garnet-red color. It does not fuse or melt 

 in boiling water, but becomes softer and more elastic; in the flame of 

 a candle it melts and takes fire, burning with a bright luminous flame, 

 giA'ing off' gas and a strong bituminous odor. It is not soluble in alco- 

 hol, and but sparingly so in ether, in both of which respects it differs 

 from elaterite. In the United States it occurs near Scofield, Carbon 

 County, and in the Uinta Mountains of Wasatch County, Utah (Speci- 

 mens Nos. 53356, 67265, 67860, U.S.N.M.). 



Albertite. — This is a brilliant jet black bitumen compound break- 

 ing with a lustrous, conchoidal fracture, having a hardness of between 



^ W. Merivale, Engineering and INIining Journal, LXVl, 1898, ]). 790; also the 

 Mineral Industry, YI, 1897, p. 54. 



