230 BROWN & HERON: GEOLOG? ANJ) ORE DEPOSITS OF TAVOY. 



(8) mica is nearly always present and sulphides very often ; 



(9) secondary movements of the fissures are common. 

 According to Bleeck ' "Individual veins, each one continuously 

 Length of vein.. Vil, . vil ^ '» thickness, have been traced for 



considerable distances (a quarter of a mile or 

 more) in the granite but only along the strike. Nothing as yet is 

 known of the conditions to the dip." The writer is evidently refer- 

 ring to certain veins in the granite between Talaingyachaung and 

 Byaukchaung. 



Maxwell Lefroy 2 writes :— " The important question- of lode conti- 

 nuity, horizontal or vertical, is one which has been severely neglected, 

 so that not much information can be given. The longest outcrop 

 hypotenuse the author has heard of, and has examined throughout, 

 is upwards of 7,000 feet from the summit to close down to the base of 

 a granite hill, 1,912 feet in height, which implies the dip angle to be 

 15° 50' throughout the 7,000 feet of its south side and the base to be 

 over 6,700 feet in length. Owing to the excessive pitch of the 

 opposite side of the hill it was impossible to determine the existence 

 ob absence of a corresponding outcrop, though some of the fifteen 

 lodes found on the southern slope must have their counterparts 

 there, as the water courses at the foot contain much quartz and ore." 



Morrow Campbell 3 states, " the most marked peculiarity of our 

 veins is that they usually occur in groups parallel and close to one 

 another, often very numerous and frequently of short length. We 

 often find a second parallel series intersecting the first. Such 

 deposits usually end abruptly along the strike, the ground outside 

 not having been fissured or cracked. The longest vein in the district 

 extends for several miles northward from the vicinity of Yewaing. 

 It strikes about X. 10° W.-S. 10°E., practically parallel to the axis 

 of the granite ridge. It is certainly one of the oldest veins in the 

 district, has undergone several re-openings and contains wolfram 

 with iron, copper, lead ami zinc minerals." Dr. Morrow Campbell 

 is here referring to the well known Kadando vein. its limits 

 in either direction are not known. 



The length of a vein naturally depends on the length of the frac- 

 ture which contains it, and it is subject to at least all the variations 

 of that original fracture. Fractures parallel to the strike of the 



1 Bloock (2), p. 63. 

 *Lclro.r;20), p. 88. 

 »J. M. "Campbell, (9), p. 5. 



