242 GEOLOGY OF ASPEN MINING DISTRICT, COLORADO. 
table. No.1 is the partial analysis of a fresh Weber rock, which chances to 
be a nearly typical dolomite: 
Analyses of limestones from Weber formation in Clark tunnel at Lenado. 
1 2. 3 
SiO Nee Se a ree 12.12 | 18.67 | 55.98 
AUO RES OA SEE amen 3.97 8.31 | 20.22 
Ral Oy Gaveny une Mae Wear 2.06 2.60 7.46 
CaO pee Seok ais Saeioue 25.63 | 36.98 3.05 
MipOR ei, 55 Rene edd eal ieanl5eo7 72 1.01 
From these analyses it appears that the process of disintegration is a 
removal of the soluble material, chiefly calcium and magnesium carbonates, 
and the consequent concentration of the silica and alumina, the result being 
an impure clay. 
LIST OF MINERALS. 
Following is a list of minerals thus far recognized megascopically in 
the immediate vicinity of Aspen: 
Sulphides: Galenite, sphalerite, pyrite, polybasite, tetrahedrite, tennantite, 
chalcopyrite, argentite, bornite, pyrargyrite. 
Sulphates: Barite, gypsum, anglesite, epsomite. 
Carbonates: Calcite, aragonite, dolomite, siderite, cerussite, smithsonite, azu- 
rite, malachite. i 
Oxides: Hematite, limonite, wad, minium (?), melaconite (?), cuprite (?). 
Silicates: Calamine (?), chrysocolla. 
