THE PROSPECTOR'S HANDBOOK'. 



Lodes, the ordinary fissure vein running through various 

 strata, and the gash vein, though wide at the surface, pinch- 

 ing out. 



Beds of ore, interstratified between other beds. For in- 

 stance, coal, iron ore (especially in the Oolite formation), 

 copper ore in shale, silver and lead ore in sandstone, &c. 

 Deposits irregularly stratified. Contact deposits between 

 two formations where the deposit lies on the older one, &c. 



Irregular deposits, such as pockets, &c., which lie some- 

 times in various formations. Contact ' deposits, network of 

 veins, and where mineral is diffused through rocks, or in 

 small cracks, or in dykes, or scattered about country rock 

 near the walls of a lode.* 



Superficial deposits, such as nearly all the diamond and 

 gold alluvial diggings, stream tin deposits, &c. 



With regard to the nature of the veins in lodes, the metal- 

 bearing minerals are scattered throughout the vein stuff, or 

 in nests and strings ; sometimes they may be found next to 

 the " hanging" and " foot" walls, or in many cases in 

 regular symmetrical layers between layers of the different 

 substances in the gangue, as in Fig. 16. 



The angle which the plane of a stratum or lode makes 

 with the horizon is called the dip; the line where the plane 

 cuts the horizontal plane is called the strike. As it is of 

 paramount importance for the geologist to thoroughly under- 

 stand the full meaning of these terms, the following explana- 

 tion will be of use. 



If a sheet of note-paper be held so that one leaf is hori- 

 zontal and the other hangs down, the angle which the latter 

 makes with the former is the dip, and the line where the 

 two leaves are connected is the strike. Suppose the plane 

 of the lower leaf sloped towards the east and made an angle 

 of 45 with the horizontal leaf, it would be said to dip 

 45 E., and the strike (which is at right angles to the direc- 

 tion of the dip) would run north and south. The line in 

 which a stratum or lode cuts the surface is called the " out- 



* In composite lodes several veins may run through a formation ; 

 so the boundaries of these veins must not be mistaken for the real 

 boundary walls. Between the real walls the whole formation may be 

 metal-bearing 1 . 



