650 



C. LE NEVE FOSTER ON THE GREAT PLAT LODE 



blende, chlorite, iron-pyrites, and a little copper-pyrites, fluor, and 

 tin-stone. Of this last mineral, the rock contains 2-§ per cent. The 

 most remarkable point with regard to this lode is the occurrence of 

 numerous pseudomorphs of quartz after orthoclase, many an inch 

 long by | inch wide ; and they show out very plainly in the dark 

 ground formed by blende and chlorite. Some of the pseudomorphs 

 contain small grains of cassiterite. 



Fig. 9. —Plan of Lode at the Lovell Mine. 



A. Granite. 



B. "Cab." 



CD. Main joint. 



EF. Joint 



The lode is traversed by numerous joints, which are mere planes 

 of division in the rock ; the principal ones dip and strike at the 

 same angle as the lode itself. When, however, a joint diverges, 

 it carries " lody stuff " with it. Thus if a joint, E F, goes off from 

 the main joint, C D (as shown in plan, fig. 9), a little tin-stuff will be 

 found following it for a short distance into the granite. 



The north lode is much lighter in .colour than the south lode, 

 owing to the absence of blende, and is a mixture of quartz, mica, 

 gilbertite, a little iron-pyrites in cubic crystals, tourmaline, and tin- 

 stone. It is from 10 to 15 feet wide. 



It must not be supposed, however, that these so-called lodes or 

 masses of tin-bearing rock run continuously from one end of the mine 

 to the other. Unfortunately they only occur in bunches here and 

 there ; and when these gradually come to an end on all sides, the 

 lode becomes a mere joint in the clean granite. 



South- Wendron mine, which adjoins The Lovell on the S.E., is 

 worked upon a pipe of tin-bearing rock of a somewhat remarkable 

 character (fig. 10). The easiest way of giving an idea of it is to describe 

 it as a very irregular cylindroid of stanniferous rock, merging gradually 

 on all sides into granite, with its axis dipping at an angle of 49° 

 from the horizon in a direction N. 25° W. (true). The longer 

 axis of the oval section of the pipe varies from 20 to 60 feet in 

 length, whilst the shorter is about 10 feet. The mass consists of 

 quartz, mica, gilbertite, a little iron -pyrites, and tinstone, and is tra- 

 versed by a few irregular joints : the stuff is usually cavernous or 



