416 FERGUSON. 



ores, although in similar ores from the Beuguet district this mineral is 

 present. The caleite, vrhere found, is generallj^ associated with quartz 

 in more or less parallel bands ia the same vein, and -when a piece of what 

 appears to be massive caleite is dissolved in h3-drochloric acid, it always 

 if found to leave an intricate network of fine quartz ribbons, proving 

 later action of siliceous solutions. The oxidized zone shows a marked 

 change in appearance. Lines of weakness parallel to the walls have 

 acted as channels for the surface-water, with the result that concentra- 

 tion of the different minerals in parallel bands has been accomplished, 

 especially near the footwall where the motion generally has been greatest. 

 The caleite as a rule has been largely dissolved and carried away, although 

 in part redeposited in vugs in the vein and wall rock. The quartz has 

 become leached through the loss of its manganese content, the manganese 

 oxide having been deposited in bands, and, less commonly, patches, some- 

 times of nearly pure sooty pyrolusite, but more commonly broken quartz 

 covered with manganese oxide. Similarly, the pj^ite has been oxidized 

 and deposited in reddish bands of iron oxide. The effects of these 

 changes on the quartz are the forming of 'Tioneycomb" quartz where the 

 caleite and manganese has been carried away. This is generally best 

 developed in the central parts of the veins where the movements have 

 not been so intense and consequently the banding not so pronounced. 

 Another feature consists in the bands of heav}^ massive quartz found 

 throughout the veins. Where narrow, these are white, although some- 

 what stained with iron oxide, but in the wider parts they as a rule 

 show an unoxidized core of blue p}Titized quartz. All stages of this 

 alteration can be seen in different parts of the district from the first 

 leaching of the blue quartz along small fissures, to the final stage of 

 oxidation where bands of massive quartz a meter or more in thickness 

 have been completely leached. The country rock in the oxidized zone is 

 much altered near the veins, especially on the footwall side, this altera- 

 tion often extending for several meters from the walls of the vein. The 

 tj^ical alteration product is a brown, clay-like rock generally showing 

 traces of its original porphpitic or fragmental structure, and much 

 stained by manganese. Throughout the district, this decomposed rock, 

 whether of igneous or pjToclastic origin, has the name of ''porphyry." 

 It is characteristically cut by a great number of small quartz stringers, 

 and more rarely caleite. These often carry values. 



Undoubtedly there is, in such loose material which forms a great part 

 of the veins, a certain enrichment due to the transportation downward 

 of the fine gold, either mechanically or in solution, or by both methods. 

 As a general rule, manganese bearing veins, which at their outcrop may 

 be nearly barren, carry values increasing progressively downward toward 

 the sulphide zone. Developments have not as yet proceeded far enough 

 to determine how important this feature may be, but the fact of the 



