1907] Geology Resources of Trinidad and Barbados 77 



that of the lake, since it has evidently picked up certain inorganic- 

 as wel; as organic, substances in its passage from the lake to the 

 sea, the movement having apparently been made when the 

 mineral was in a somewhat plastic condition. In composition the 

 asphalt contains about 40 to 50 per cent, of bitumen, about 30 per 

 cent, of water, the remainder consisting of the impurities men- 

 tioned. 



The mines of manjak, located near San Fernando, are also 

 exceedingly interesting. The mineral is also an altered pet- 

 roleum, and now occurs in fissures which traverse the shales and 

 sandstone of the oil-bearing series in the same way as the albertite 

 mines in New Briinswick have been formed. Their position is 

 near the crest of an anticline, and the fissures have been formxed 

 in the period of disturbance or crushing by which the anticlinal 

 folds were produced. 



The mineral manjak is a very pure variety of asphalt, carry- 

 ing from 00 to 95 per cent, of bitumen. A certain amount of 

 impurity is found in the forni of clay particles, evidently detached 

 from the sides of the fissures in the process of vein formation. It 

 is jet black, glossy, and brittle, and can be lighted in the flame of a 

 match, dropping hke sealing wax and taking readily the impres- 

 sion of a seal. In this respect it differs somewhat from New 

 Brunswick albertite which does not fuse readily, but splinters on 

 the application of heat. Manjak is largely used in the manufac- 

 ture of high grade black varnishes, insulating paints for electric 

 conductors, waterproof paints, etc. The veins vary greatly in 

 size, the principal one worked having increased from a width of 

 about seven feet at the surface to over .30 feet at a depth of 200 

 feet. Much of the mineral in the upper 100 feet is what is known 

 as columnar, as if the vein matter had been shattered by pressure, 

 but at lower depths the massive form, comes in and forms the 

 greater portion of the deposit. In its conchoidal fracture it 

 resembles strongly the albertite of New Brunswick as also in general 

 aspect. The difference in the mineral is apparently due to meta- 

 m.orphism on the part of the latter, which occurs in Devonian rocks 

 while the manjak is found, both in Trinidad and Barbados in the 

 soft Tertiary clays and is comparatively unaltered from its pitch 

 condition, in this respect presenting analogies to anthracite and 

 lignite in the coal series. The limit of the veins in depth ha:^ not 

 been ascertained at any one point, with one exception in Barbados 

 where in a shaft at a depth of 1 50 feet the manjak became soft and 

 soon passed into a thick, asphaltic oil which could be removed by 

 baihng. The Barbados mineral is somewhat purer and ap- 

 parently softer than that of Trinidad and commands a higher 

 price in the market, some portions of the output reali7ing as 



