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LORENCITO CANYON MINE GEOLOGY TECHNICAL REPORT SECTION 1 -INTRODUCTION The objective of this report is to provide methodologies for stratigraphical and structural geology determination in the permit area in accordance with the Regulations of the Colorado Mined Land Reclamation Board. Several past exploratory activities have occurred at the Lorencito Canyon Mine site in 1970's and 1980's. Over 100 boreholes and corings have been conducted within the permit area during that time. Additionally, substantial site work has been conducted since the beginning of 1996. Methodologies for the work conducted in 1996 are provided in Section 2 of this repot. Furthermore, other field studies have been conducted in the Raton Basin. "The Hydrogeology of the Raton Basin" (Howard, 1982) has been utilized in addition to field studies conducted at the site to provide a comprehensive overview of the stratigraphy and structure of the site. Field work accomplished during the 1996 baseline year included drilling 10 alluvial boreholes and 18 bedrock boreholes. Additionally, monitoring of groundwater, springs, seeps and surface water has been accomplished. The current study in addition to past studies conducted at the site have been used to describe the site structural geology. • SECTION 2 -METHODOLOGY Determination of stratigraphy and Structure Both literature review and field derived data were utilized to determine site structural and stratigraphic characteristics. The background field study, "The Hydrogeology of the Raton Basin" (Howard, 1982), was utilized to determine site specific geological and structural data in addition to interpretations of lithologic logs and electric logs from data obtained since the beginning of 1996. Several past exploration activities have occurred on the site. These past studies have included drilling of 135 boreholes. Lithologic logs and electric logs have been interpreted from these boreholes and used to determine site structural and geological data. During the 1996 exploration, 18 exploratory boreholes and 10 alluvial boreholes were drilled at the site. Drilling was performed using a Midway 1500 drill rig. Air, water and limited use of foamer were used as drilling fluids. Surface casing was initially installed in the 16 exploratory borings by drilling a 12-inch diameter hole to approximately 20 feet and installing a 10 inch diameter conductor pipe. Each borehole was drilled using a 7-7/8 inch drill bit. Coring was performed in some areas by using a 5-5/8 inch drill bit to core point and a 4-7/8 inch core barrel utilized to cut the core. Rock core and well cutting grab samples were collected in a sampling bucket at five foot intervals or during lithologic changes and were described m the field with a lOx . hand lens according to color, grain size, mineralogy and grain shape. Lithologic logs were prepared by a geologist for all boreholes. Electric logs were run in some boreholes including Geology-075/April 2J, 1997 1 (revised 4/21/97)