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Extracting  cavity-lining minerals, Linwood Mine, Scott County, Iowa

Sulfide mineral occurrences on the western fringe of the Upper Mississippi Valley Zinc-Lead District

My research has centered around minor accumulations of epigenetic sulfide mineral-bearing deposits in eastern Iowa, western Illinois and southwestern Wisconsin. This work includes descriptions and interpretations of several previously unreported deposits. Using mineralogy, paragenesis, spatial relationships between mineralization and host rocks, and results of sulfur, carbon and oxygen isotopic analyses, I have attempted to establish a genetic relationship (or lack thereof) between these deposits and those in the formerly commercial Upper Mississippi Valley Zinc-Lead District. I have also studied silicic wallrock alteration in chert-bearing host-rocks in northeastern Iowa and southwestern Wisconsin. Using cathodolumin-escence I have learned that much of the earlier-described hydrothermal "jasperoid" is in reality pre-hydrothermal chert. More recently, my research has focused on mineral deposits associated with late Paleozoic karst, the most prominent of which (in Iowa) occur in the Linwood Mine near Davenport. Several hundred acres of this room and pillar mine, and the limestone cavities and their fluviatile sediment fillings and mineral linings, have been mapped. This information has been entered into a geographic information system (GIS), which has proven to be an excellent tool for relating the spatial distribution of the cavities and their contents to structural and stratigraphic characteristics of their limestone hosts. Below is list of selected publications that are pertinent to this research.

Garvin, P.L, 1982, Sulfide mineralization at Mineral Creek Mines, Allamakee County, Iowa: Iowa Acad. of Science Proc. v. 90, p. 44-49.

Ludvigson, G.A., Bunker, B.J., Witzke, B.J. and Garvin, P.L., 1983, A burial diagenetic model for the emplacement of zinc-lead sulfide ores in the upper Mississippi Valley, U.S.A.: in Proc. of the Internat. Conf. on Mississippi Valley-Type lead-zinc deposits, G. Kisvarsanyi, S. K. Grant, W. P. Pratt, and J. W. Koenig, eds., Univ. of Missouri-Rolla, P. 497-515.

Garvin, P.L, 1984, Hydrothermal mineralization of the Mississippi Valley type at the Martin-Marietta Quarry, Linn County, Iowa: Iowa Acad. of Science Proc. v. 91, p. 70-75.

Garvin, P.L., Ludvigson, G.A. and Ripley, E.M., 1987, Sulfur isotope reconnaissance of minor metal sulfide deposits fringing the upper Mississippi Valley Zinc-Lead District: Econ. Geol. v. 82, p. 1386-1394.

Garvin, P.L., and Ludvigson, G.A., 1988, Mineralogy, paragenesis and stable isotopic compositions of mineral deposits associated with late Paleozoic karst fills in Johnson County, Iowa, in Ludvigson, G.A. and Bunker, B.J., eds., New perspectives on the Paleozoic history of the Mississippi Valley: an examination of the Plum River fault zone: Great Lakes Section, Society of Economic Paleontologists and Mineralogists, 18th Annual Field Conference Guidebook, p. 161-170.

Garvin, P.L., and Crawford, D.M., 1992, The minerals of the Linwood Mine, Scott County, Iowa: The Mineralogical Record, v. 23, p. 231-238.

Garvin, P.L., and Ludvigson, G.A., 1993, Epigenetic sulfide mineralization associated with Pennsylvanian paleokarst in eastern Iowa, U.S.A.: Chemical Geology, v. 105, p. 271- 290.

Garvin, P.L., 1995, Paleokarst and associated mineralization at the Linwood Mine, Scott County, Iowa: Journal of the Iowa Academy of Science, v. 102, p. 1-21.

Garvin, P.L., 2003, Cathodoluminescence as a means for distinguishing hydrothermal from pre-hydrothermal quartz in sulfide-bearing mineral deposits on the northern fringe of the Upper Mississippi Valley Zinc-Lead District, NE Iowa and SW Wisconsin: Journal of the Iowa Academy of Science, v. 110, p. 22-29.
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Calcite basal twin, Conklin Quarry, Johnson County, Iowa.  Specimen is 7 cm across

Book: Iowa's Minerals

Almost everyone has an interest of some kind in minerals. We depend upon them because they are the chief components of a wide variety of useful commodities, like plaster, ceramic, concrete, building stone and road surfacing materials. Mineral industries are a vital part of the economy of every state in the nation and of virtually every country in the world. We spend considerable sums of money in order to adorn ourselves with mineral gems. Some people are attracted to the natural beauty of minerals and simply collect them. That minerals have status in Iowa is evidenced by the fact we have our own state rock--the quartz geode. However, the value of minerals is more than monetary and aesthetic. Minerals are the fundamental building blocks of which Iowa, and the rest of the Earth, are made; therefore, understanding their natures and origins is an essential prerequisite to interpreting Iowa’s geologic history. Indeed, minerals are essential elements of the language in which that book of history is written.

Iowa's Minerals, begins with a brief treatment of mineral origins, commencing with the oldest minerals (with ages well in excess of 1 billion years) to those most recently formed. With the exception of the most ancient minerals, the vast majority of Iowa’s minerals result from the solvent and depositional action of water.

Although Iowa probably does not rank anywhere near the top of the list of states with regard to mineral collecting, minerals of exquisite quality have been, and continue to be found within its borders. Organized groups of mineral collectors regularly search for Iowa’s mineral collectibles. The second chapter of this book provides information for collectors, including how to obtain access to collecting areas and rules of safety. Iowa’s major mineral occurrences (a total of 26) are described in chapter 3. These descriptions also contain information for mineral collectors.

Iowa’s minerals are valuable not only to collectors, but also to industry. During the 150+ years of its statehood, Iowa has been a major producer of lead, coal, limestone, gypsum and sand and gravel. The history of Iowa’s mineral industries can be traced back to pre-Euroamerican settlement, when Native Americans quarried a variety of materials for utilitarian and religious purposes, and for warfare. The first European mineral producers were the French, who began mining lead as early as 1650. The long record of lead, coal, gypsum and limestone mining in Iowa contains rich history. Mineral industries continue to make a very important contribution to the economic health of Iowa. In aggregate, they are second only to agriculture in product value.

Woven into the fabric of Iowa’s history are interesting stories involving its minerals. Well known is the story of the Cardiff Giant Hoax, and accounts of meteorite falls of the late nineteenth century are familiar to some. These and additional stories, including the Ottumwa Coal Palace, the MacGregor sand painter, and how the geode became the Iowa state rock, make fascinating reading.

No book on Iowa’s minerals would be complete without pictures of the minerals themselves. Iowa’s Mineral Showcase features a few of the best, in full color. Photographed with the assistance of an artist/photographer, these might be considered the centerpiece of the book. Click here to see photographs of Iowa’s minerals.

In summary, this book is written for students of mineralogy of all ages, for educators, for collectors and for those interested in Iowa history. For the general reader it explores the fascinating history of Iowa’s mineral industries and its mineral lore. Its purpose is to broaden our awareness of, and appreciation for, Iowa’s mineral endowment, and to deepen our understanding of how that endowment came to be. Iowa’s Minerals is published by the University of Iowa Press. (http://www.uiowa.edu/~uipress)
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Lake Channel, near the Snake River in Power County, Idaho; a major collecting area for lithic artifacts

Lithic Artifacts from the southern margin of the Eastern Snake River Plain, Idaho

Rekindling a long-dormant interest in North American Indian archaeology, I have recently begun research on a collection of lithic artifacts that I acquired during my high-school years. The collection numbers in excess of 5000 individual artifacts, most of which were gathered from several sites along the southern margin of the eastern Snake River Plain in Idaho. I have catalogued these by raw material, size, typology and other flaking characteristics. The information has been entered into a relational database, from which I am attempting to compare artifact attributes from specific collecting sites.

 
Research