192 BULLETIN 42, UNITED STATES NATIONAL MUSEUM. 



celleut series of. photographs of characteristic scenes about the works 

 and mine, both above and below ground. 



A working space 1,500 feet below ground is shown in PL. xxv, a view 

 of a shaft house and dressing floor in PL. xxvi, a general view of the 

 reduction works in pl. xxvii, and a view of a furnace in pl. xxviii. 



(1) Hanging wall, or " alta," as it is called, from the Spanish word meaning high. 

 This invariably forms one of the boundary walls of the ore-bearing vein, the line of 

 contact of the two being usually very distinct. The physical properties of the rock 

 are well represented in the specimen, although its color and hardness vary consider- 

 ably. It is usually black, but is sometimes white, gray, brown, or yellow, the last 

 color being characteristic of surface "alta." It is sometimes found in the form of 

 clay, at others it is slate or shale and harder and more tenacious than the specimen. 

 (66436.) 



Nos. 66437 to 66454 inclusive are characteristic specimens of ore and 

 veinstone from the main ore chute. 



(1) Nearly pure cinnabar, from the 1,500-foot level. Large bodies of this quality of 

 ore are frequently found. (66437.) 



(2) Cinnabar, mixed with its characteristic gangue, consisting principally of dolo- 

 mite, talc, calcite, and bitumen. These specimens are typical, the bulk of the ore 

 taken from the mine being found in this condition. (66438, 66439, and 66440.) 



(3) Globules of native mercury, in characteristic gangue. Specimens of this kind 

 are very common, but the yield of quicksilver from them is small. (66441.) 



(4) Globules of native mercury, in characteristic gangue shows especially cavi- 

 ties containing bitumen. (66442.) 



(5) Globules of native mercury, in characteristic gangue. Avery handsome speci- 

 men, showing large globules on crystallized dolomite. (66443.) 



(6) Crystals of cinnabar, which are sometimes found with a few globules of free 

 mercury in cavities. (66444.) 



(7) Cinnabar, very handsomely crystallized. (66445.) 



(8) Dolomitic veiustone, often found in large slabs. Scored and polished naturally. 

 (66446.) 



(9) Dolomitic veiustone, well crystallized. Occurs in seams and cavities, inter- 

 mixed with other vein matter and ore. (66447.) 



(10) Dolomitic veinstone. Contains more of the carbonates of iron and calcium 

 than is common. (66448.) 



(11) Veiustone, from old workings near the surface. The vein from this part of the 

 mine dift'ers from that of the lower levels in its color, and in its being intermixed, 

 more or less, with the hanging wall material. (66449 and 66450.) 



(12) Veiustone, from the surface, in the vicinity of the place where cinnabar was 

 first discovered. (66451.) 



(13) Vein rock, from a '' labor" or working space on the 1,800-foot level. Contrary 

 to the usual condition in productive vein rock, considerable free mercury and very 

 little cinnabar are found here. (66452. ) 



(14) Native mercury, collected from the labor just mentioned. After blasting it 

 often runs out of the cavities in streams. (Ii6453. ) 



(15) Cinnabar and veinstone. Interesting chielly on account of the pyrite which 

 it contains. This intermixture is quite common. Sulphides of several other metals 

 are also found, but only occasionally, and in small quantities. (66454.) 



(16) Serpentine, which forms the foot wall of the vein. It is usually in contact 

 with and underlying the vein, but in absence of the vein it comes in sharp contact 

 with the hanging w.ill. Sometimes there is a strong line of demarcation between 

 the vein and foot w.all ; at others they shade off almost imperceptibly into each 

 Other. (66455.) 



