EVENING STAR MINE. 433 



From the bottom of the Main shaft an incline is started in the lime- 

 stone for the purpose of exploring the ground to the east; in it the bedding- 

 planes of the limestone are very indistinct, but from data obtained at other 

 points it is deduced that its dip must be nearly 45. 



In general it may be said of the ore bodies of the Catalpa mine that, 

 while irregular and pockety, they have been much richer than the thicker 

 bodies to the north. 



Evening star mine. This claim, located on a narrow strip of ground little 

 more than half the normal width of a claim, left between the Catalpa and 

 Morning Star, included by good luck the thickest and widest portion of 

 the bonanza, and has probably proved more profitable to its owners, as a 

 legitimate mining enterprise, than any other in the region. 



It is opened by two vertical shafts, known as the Main and Upper 

 shafts, between which the ore body stretches in an almost continuous sheet 

 and beyond which in either direction but little ore has been found. 



Main shaft. The Main shaft, as shown in Section D, was sunk through 

 the White Porphyry, across a great thickness of iron vein material and 

 through an underlying sheet of Gray Porphyry, into a second body of vein 

 material, at the base of which was found a thin bed of quartzite. This is 

 probably a portion of the Parting Quartzite, and the second iron body is 

 therefore the replacement of a portion of the Blue Limestone split off from 

 the main body by the intrusion of the Gray Porphyry. The fact that this 

 underlying sheet has been actually cut here is extremely important, since 

 its existence in the southern portion of the hill, between this point and the 

 oufcrops on the slopes toward California gulch, has been only inferentially 

 proved by isolated masses supposed to be offshoots from it. 



A dike-like body of Gray Porphyry is also cut in the upper workings 

 adjoining the shaft. As shown here, it is six feet in width, runs in a north- 

 east direction, and has a dip of 70 to the northwest. In places, especially 

 toward the center of the mass, it is in exceptionally fresh condition, its matrix 

 being a semi-translucent hornstone like mass, containing abundant crystals 

 of limpid quartz with feldspar. By decomposition, which is often com- 

 pleted in a very short distance from the unaltered parts, the groundmass 

 becomes perfectly opaque and white, and assumes a mottled appearance 



MON XII 23 



