CONTENTS. 
V 
Chapter III.—Description and petrology of the metamorphic and igneous rocks—Continued. 
Tertiary volcanic rocks—Continued. 
Basic dike rocks—Continued. 
Trachydolerite (Isabella type). 
Vogesite. 
Monchiquite.*. 
Summary. 
Breccia. 
Rhyolite. 
Petrology of the district. 
Granite group. 
Olivine-syenite group. 
Rocks of the Cripple Creek volcano. 
Mineralogical characters. 
Chemical characters. 
Composition of the rocks expressed by diagrams. 
Average rock of the Cripple Creek volcano. 
Order of succession of the rocks. 
Summary. 
Chapter IV.—General mineralogy of the district. 
List of minerals. 
Notes on occurrence. 
Native elements. 
Gold. 
Silver. 
Copper.:. 
Tellurium. 
Tellurides. 
Coloradoite. 
Kalgoorlite.. 
Melonite. 
Altaite. 
Hessite. 
Petzite. 
Tetradymite. 
Nagyagite. 
Sylvanite. 
Krennerite... 
Calaverite. 
Oxidized tellurium compounds. 
Em monsite. 
Tellurite. 
Sulphides and sulphantimonites. 
Pvrite. 
Marcasite. 
Molybdenite. 
Stibnite. 
Cinnabar . 
Galena. 
Zinc blende (sphalerite). 
Chalcopyrite. 
Tetrahedrite. 
Chalcocite. 
Arsen opyrite. 
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