|2012 venture||2015 venture|
The name Silver City dates from the 1870s, when prospectors thought that silver was present. This led to a short-lived mining boom and swindle, as there is no silver. Instead, a rare rock called lamproite (lamprophyre) is found here. It was emplaced as an intrusive pipe-and-sill structure during the late Cretaceous (~90 million years ago), and the adjacent sedimentary rocks were altered by contact metamorphism and hydrothermal circulation (Wojcik and Knapp 1990; Aber and Aber 2001).
The Silver City lamproite is closely related to the nearby Rose Dome intrusion, also in Woodson County, as well as similar intrusive pipes at Smoky Butte, Montana and West Kimberley, Australia (Cullers and Berendsen 2011). In other parts of the world, lamproite contains diamonds, but none are known here. The lamproite is mined nowadays in an open pit for a commercial product named Micro-Lite, which is used as a cattle-feed supplement.
Right: street sign on the road leading to the Micro-Lite plant.
The day of our visit was forecast to have strong south to southwest wind at 20-30 mph, and the forecast proved to be accurate! We set up on the southern rim of the mine pit and utilized a small delta kite to lift our Canon S70 and Rebel 300 SRL camera rigs. The former has a wide-angle lens; the latter was equiped with a superwide-angle lens. The delta performed remarkably well, considering the gusty wind. The delta lifted both rigs and was relatively stable in flight.
View toward SE
View toward SW
View toward NE
|Ore processing equipment, storage silo, maintenance buildings and office complex on the southern side of the open-pit mine. View toward southeast.|
|Eastern portion of the open-pit mine. This section was worked most recently prior to our visit. The lamproite is excavated using earth movers to scrap up the soft, clayey rock.|
|View toward southern margin of the mine. Kite flyers are set up on the rim at the van near center of view. Note kite line.|
|Westward view of the mine pit and surroundings. Drainage channels are cut through the wall rocks toward upper left and at the far end.|
|View toward the northwest showing the northern wall of the open-pit mine. Note the cluster of students on the mine wall at scene center.|
|Near-vertical shots Left: students on the northern wall of the open-pit mine. They are searching for various minerals in the contact metamorphic rocks adjacent to the intrusion. Right: Tracks in the lamproite were made by earth movers.|
We noticed the mining operation had expanded eastward considerably since 2009. A mild winter and warm spring had caused early greening of the winter wheat, grass and trees in the surrounding landscape.
View toward NE
View toward NW
|Left:: overview of kite flying site on the southern margin of the mine. Kite flyers just below scene center. Right: self-portrait of kite flyers: JSA (left), Megan Sprague (center), and Gayla Corley (right).|
|Views over the mine. Left: looking northward. Note people to left side. Right: looking westward with a person in lower right corner.|
|Overviews of the mine site to the east (left) and west (right). The eastern portion is newer, having been excavated during the past few years. The older western side has been dug out for several decades and is deeper. Both portions continue to be worked as shown by earthmover tracks.|
|Close-up shots of the processing plant, storage silo, service and office buildings, and heavy equipment. The mine was not operating, so earthmover and bulldozer are parked for the day.|
|Spring burning of tallgrass prairie and oak forest understory in the surrrounding Chautauqua Hills vicinity. By the end of the day heavy smoke and ashes covered the terrain across a large portion of eastern Kansas.|