Editing Fredericktown, Missouri (section)

==Geology==
Fredericktown is nearly unique in the United States for the variety of minerals and metals that have been found and commercially mined nearby, including [[lead]], [[iron]], [[copper]], [[silver]], [[cobalt]], [[nickel]], [[zinc]], [[tungsten]], and small amounts of [[gold]], all of which have been mined at various times within {{convert|20|mi|km}} of the town. The mines immediately east of the town, in what has been called the [[Lead Belt|Old Lead Belt]], were at one time one of the largest sources of lead in the United States. One of the oldest, and possibly the oldest, lead mines on the North American continent can be found six miles (10&nbsp;km) north, in [[Mine La Motte, Missouri|Mine La Motte]]. While little or no iron has ever been mined in Madison County, very large deposits of mostly [[hematite]] with associated [[magnetite]] exist {{convert|20|mi|km}} to the west in [[Iron County, Missouri|Iron County]]. These deposits have been mined since at least [[American Civil War|Civil War]] times.

West of Fredericktown but still within Madison County is the [[Silver Mines Recreation Area]],<ref>[http://www.fs.usda.gov/wps/portal/fsinternet/!ut/p/c4/04_SB8K8xLLM9MSSzPy8xBz9CP0os3gDfxMDT8MwRydLA1cj72BTJw8jAwjQL8h2VAQAzHJMsQ!!/?ss=110905&navtype=BROWSEBYSUBJECT&cid=null&navid=110000000000000&position=BROWSEBYSUBJECT&recid=21840&ttype=recarea&pname=Silver%20Mines%20Recreation%20Area Silver Mines Recreation Area, US Forest Service]</ref> which is situated along a steep river gorge of the [[St. Francis River]]. This area contains the ruins of both a 1920s silver mine and a [[World War II]] era [[tungsten]] mine. Examples of the minerals that were once mined can still be found in the abundant tailings on the south side of the St. Francis River, just downstream of a now-breached stone dam. They consist of metallic-appearing sulfides such as [[sphalerite]], [[arsenopyrite]], and [[marcasite]] embedded in opaque veins of [[quartz]]. Careful searchers can also find crystals of [[wolframite]], a tungsten ore that was mined briefly during World War II when access to other sources was cut off, and small grains of [[topaz]], which caused the earlier silver miners of the area considerable economic grief by wearing out their [[Diamond drilling#Diamond core drilling|diamond-tipped drills]] more quickly than anticipated. Both highly magnetic [[magnetite]] and slightly magnetic [[ilmenite]] (titanium ore) grains can be found in patches of black sands left along the beach of the main swimming area.

Madison County also contains unique igneous rocks not found anywhere else, such as [http://gsa.confex.com/gsa/2006SC/finalprogram/abstract_100009.htm Devonite] {{Webarchive|url=https://web.archive.org/web/20110608160123/http://gsa.confex.com/gsa/2006SC/finalprogram/abstract_100009.htm |date=June 8, 2011 }}, a colorful decorative stone found only in a single igneous intrusion [[Dike (geology)|dike]] on [http://topozone.com/map.asp?lat=37.5380555555556&lon=-90.3458333333333 Mount Devon].