MINES OUTSIDE THE LEADVILLE DISTRICT. 527 



Limestone is here, contrary to what its name would indicate, quite light- 

 colored. The ore is extremely rich, but very irregularly distributed; it is 

 evidently a replacement of the limestone, there being no evidence of pre- 

 existing cavities. 



Dominion mine (L). In a prospect hole to the north of this, called the Do- 

 minion, ore is also found at the contact of the limestone and Parting Quartzite. 

 The ore body averages two feet in thickness and is said to assay from $68 

 to $500 in silver per ton. It carries brittle silver, silver glance, sulphate 

 and carbonate of copper, and some antimony. 



Sweet Home mine. On the face of the cliff, a little southeast of the Red 

 amphitheater, in the gneiss below the Paleozoic rocks, is the Sweet Home 

 mine. Its ore is found near a body of very much decomposed Lincoln 

 Porphyry, whose surfaces are covered with a yellow coating of oxide of 

 iron, containing arsenic and antimony. This mine is interesting from the 

 varieties of mineral species thus far obtained from it. Among these are 

 cuprite, fluorite (pink and blue), jamesonite, melanterite, rhodocrosite, and 

 zinkenite. 



From the Tanner Boy mine, on the southwest side of the gulch, said to 

 be a fissure deposit in gneiss, are obtained remarkably fine crystals of deep 

 red rhodocrosite, or carbonate of manganese, containing a little magnesia. 

 It occurs in very well-defined rhombic crystals, isomorphous with calcite. 

 As might be expected from the prevalence of eruptive bodies, ore is found 

 in small veins in almost every part of the Archean rocks exposed in Buck- 

 skin Canon. As yet, however, no large and important discoveries have 

 been made, and a priori the conditions for concentration of large ore bodies 

 would be less favorable here than in the overlying Paleozoic rocks. 



On the south side of Buckskin gulch, at the eastern end of the cliff 

 wall, shown in Plate XIII (p. 128), and formed by the lower Paleozoic beds 

 sloping up toward the crest of Loveland Hill, small ore bodies have been 

 opened up, following jointing planes in the White Limestone and the 

 Lower Quartzite. These deposits are generally extremely thin and of 

 limited extent. They frequently send out branches for a short distance 

 into the adjoining rock, following the stratification planes. Their ore is 

 galena, black sulphurets, and sometimes native silver. The direction of 



