No abstract

The Montezuma district of central Colorado is a small base metal-silver mining district containing vein deposits associated with a Tertairy porphyry stock. The distribution of tetrahedrite having large unit-cell edges correlates in part with the distribution of more productive mines and suggests areas favorable for further production. The abundance of galena and sphalerite in veins, but not of pyrite, also correlates with the distribution of the more productive mines.

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature. Any use of trade names is for descriptive purposes only and does not imply endorsement by the USGS.

Metals Score = Sum of the products: (workings size)X(mineral mode) where (workings size"), estimated from size of dump, is 1 for a prospect pit 2 for a small mine (3-15 m of adit and (or) shaft) A for a medium mine (15-60 m of workings) 8 for a large mine (more than '60 m of workings). and (mineral mode) is estimated from vein fragments on the dump as 1 for a trace to as much as 2 percent 2 for 2-15 percent 4 for 15-30 percent 8 for 30 per cent.or more.. The minerals whose modes are used in scoring are arsenopyrite,