Sample of spheroidal sphalerite with dendritic sphalerite, galena, and iron sulfides (pyrite plus marcasite) from the Pomorzany mine. Note the "up direction" is indicated by "snow-on-the-roof" texture of galena and sphalerite alnong colloform layers of light-colored spahlerite. Hydrothermal sulfide clasts in the left center of the sample are encrusted by sphalerire and iron sulfides. Size of sample is 20x13 cm. Photo by David Leach.
Chapter A of
Mineral Deposit Models for Resource Assessment
COVER:Sample of spheroidal sphalerite with dendritic sphalerite, galena, and iron sulfides (pyrite plus marcasite) from Pomorzany mine. Note the "up direction" is indicated by "snow-on-the-roof" texture of galena and sphalerite along colloform layers of light-colored sphalerite. Hydrothermal sulfide clasts in the left center of the sample are encrusted by sphalerite and iron sulfides. For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprodTo order this and other USGS information products, visit http://store.usgs.gov Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report.
AbstractThis report is a descriptive model of Mississippi ValleyType (MVT) lead-zinc deposits that presents their geological, mineralogical and geochemical attributes and is part of an effort by the U.S. Geological Survey Mineral Resources Program to update existing models and develop new models that will be used for an upcoming national mineral resource assessment. This deposit modeling effort by the USGS is intended to supplement previously published models for use in mineral-resource and mineral-environmental assessments. Included in this report are geological, geophysical and geochemical assessment guides to assist in mineral resource estimation. The deposit attributes, including grade and tonnage of the deposits described in this report are based on a new mineral deposits data set of all known MVT deposits in the world.Mississippi Valley-Type (MVT) lead-zinc deposits are found throughout the world but the largest, and more intensely researched deposits occur in North America. The ores consist mainly of sphalerite, galena, and generally lesser amounts of iron sulfides. Silver is commonly an important commodity, whereas Cu is generally low, but is economically important in some deposits. Gangue minerals may include carbonates (dolomite, siderite, ankerite, calcite), and typically minor barite. Silicification of the host rocks (or quartz gangue) is generally minor, but may be abundant in a few deposits. The deposits have a broad range of rel...