MINES BETWEEN ALTMAN AND GOLDFIELD. 
389 
ISABELLA MINE. 
PRODUCTION AND DEVELOPMENT. 
This property, owned by the Isabella Mines Company, consists of about sixteen 
claims forming an irregular area of 160 acres on the northern slope between Bull 
Cliff and Bull Hill. It was one of the most, productive mines of the camp from 
1895_to 1900. In 1899 the output reached the maximum, $968,000. The total 
sum is between $3,000,000 and $4,000,000, and dividends have been paid to the 
amount of $675,000. For the last few years the mine has been worked in a small 
way by lessees. 
The mine is opened by the vertical Lee shaft, from which fourteen levels are 
turned. The elevation of the collar is 10,460 feet, and of the sump 9,332 feet. 
The first eight levels average 70 feet apart, while from 8 to 14 the distance between 
them is 100 feet. Level 3 is 202 feet below the collar; level 7, 438 feet; level 8, 
520 feet; level 10, 720 feet; level 14, 1,120 feet. The Buena Vista incline is sunk 
on the vein 800 feet north-northwest of the Lee shaft, and follows it down to level 7. 
Level 3 corresponds with Victor level 5, and level 11 *with Empire State level 11. 
The workings on the Pharmacist or Maloney and the Empire No. 2 veins are described 
on pages 393 and 395. There are several miles of drifts and crosscuts, chiefly on 
the Buena Vista and Cheyenne veins, which have been opened for a horizontal 
distance of 3,400 feet. 
GEOLOGICAL FEATURES. 
The croppings of the Buena Vista vein are chiefly in breccia, though between 
the Buena Vista and Lee shafts they run close to the contact of a southeastern 
projecting wing of the area of latite-phonolite which may be noted on the map on 
the northern slope of Bull Hill. For a few hundred feet southeast of the Lee shaft 
they cut through this dike-like wedge, and then continue into breccia to the Victor 
mine. 
All the drifts from the Buena Vista incline and the ten upper ones from the 
Lee shaft show latite-phonolite, while breccia prevails on levels 11, 12, 13, and 14. 
These relations are roughly shown in figs. 45 and 46. From the latter it appears 
that the intrusive mass has really the form of a dike, gradually widening toward 
the surface and dipping steeply to the southwest. 
The breccia is generally of normal character, with small but well-defined 
fragments of phonolite and latite-phonolite. It is apt to become harder and less 
pyritic some distance away from the veins, as shown in the long crosscut in the 
hanging and foot walls on levels 7 and 11. In the southeastern part of the mine 
the breccia is light colored, fine grained, and contains flat joints which in places 
clearly follow a rude stratification. The breccia near the phonolite sheet on the 
Cheyenne vein contains many fragments of that rock. Granitic fragments are 
said to be very abundant on level 14 (at present under water), and it was even 
stated that massive granite occurred on that level in the crosscut to the Cheyenne 
vein. 
A thick sheet of phonolite with a flat northwesterly dip is encountered in the 
workings south of the Lee shaft on levels 10, 11, and 12. A smaller sheet, also 
