644 C. LE NEVE FOSTER ON THE GKEAT PLAT LODE 



cross section through West Basset and South Wheal Frances, pre- 

 pared by Capt. A. James, the manager of the latter mine, shows how 

 the lode is faulted by three other lodes underlying north. 



West Wheal Frances. — I have already pointed out that if the large 

 tin-lode of this mine forms a part of the Great Plat Lode, it must 

 have been considerably shifted out of its proper line by faults. The 

 lode in many places is extremely like that of West Basset ; but very 

 often the leader becomes a quartz-vein 2 or more feet wide, and ge- 

 nerally poor in tin ; this is known as the cab. The stanniferous 

 rock is usually under the leader or the cab. The dip of the lode 

 varies from 37° to 50° in the short distance of 80 fathoms along the 

 strike. 



Pig. 4. — Section at West Wheal Basset, above the 104-fathoms Level. 





Scale lis 



■hiitsK-i ft. 



a * 6 a jo l2Teei; 



A is the leader, a red ferruginous clay- vein with fragments of capel 2 to 3 inches 

 thick. 



B C, lode and capel, i. e. stanniferous and non- or slightly stanniferous schorl- 

 rock, 9 feet thick above the leader and 6 feet thick below : there is no wall 

 between the lode and the capel, nor between the capel and the granite, G Gr. 

 The stanniferous part has usually a greyish-blue colour and is a compact 

 rock with veins and spots of quartz and cassiterite. The schorl-rock with 

 large grains of quartz in a compact black matrix is invariably unpro- 

 ductive. 



South Condurrow. — Here, again, the Great Flat Lode is entirely in 

 granite, though the thickness of that rock on the hanging wall in 

 the upper part of the mine must be small. The general features of 

 the lode are very much the same as in West Basset ; you have, in 

 fact, a narrow leader with lode and capel above and below it. The 

 tin-bearing part averages 5 or 6 feet wide, and the lode and capel 

 together will quite make up 12 ft. However, the capel is often 

 very much thicker, especially under the leader, and may reach even 

 20 feet. 



The average bearing in South Condurrow is about E. 34° N., the 

 dip 30° S. 



