MINING FOR MANGANESE



LARGE BURROW PARALLEL TO BEDDING PLANE, PERHAPS FROM A CRAB.  THE KNOBBY SURFACE REPRESENTS VERTICAL BURROWS, PERHAPS FROM ACTIVITY BY WORMS.

The Missouri River Trench is a major topographic and geologic structure trending mainly north-south in the center of South Dakota until the river abruptly turns east and then forms the boundary with Nebraska.  The Cretaceous Pierre Shale is well exposed along the entire trench, and in many places the underlying Niobrara Formation crops out.  In fact, the type section (where it was named) of the Niobrara is along the bluffs west of Yankton near the Niobrara River.  In the central part of the state the Pierre Shale has a type section along the River near the capitol of Pierre.   Many readers are familiar with these two formations if they have traveled along I-90 and crossed the river at Chamberlain.  The view of the river and the rocks is spectacular, especially if traveling from east to west.

West of  Chamberlain travelers notice a “black streak” (informally the “Oacoma Zone”) running through the Pierre Shale, actually the DeGrey Member of the Pierre.  The “black streak” is un-vegetated and many people assume the pasture and roadside has burned.  However, this “streak” has a high abundance of manganese, especially in numerous nodules, and this element seems toxic to vegetation.  These nodules were mined “by hand” in the 1930’s and shipped to Pittsburg, PA, by rail for processing and use in the steel industry (www.library.thinkquest.org).  The federal government became interested in the resource and in 1930 geologists from U. S. Geological Survey estimated the resource contained 102,000,000 tons of metallic manganese (Hewett, 1930).  In 1941, due to a need for hardened steel in World War II, the U. S. Bureau of Mines constructed a pilot plant (near mile marker 257 north side of highway) and began experimenting in mining and separation of the nodules from the shale (Cox and Beach, 1980). The mine closed in 1947 after the war.  There have been periodic studies since that time, but no additional mining, as geologists, at present, do not believe a viable market exists for the manganese nodules (Cox and Beach, 1980).  One may still observe remains of this interesting old mine.

Many of the nodules are fossiliferous, including both body fossils and trace fossils.  I recently stopped at a locality along the Missouri River and noticed a really nice burrow, perhaps a crab, well displayed on the bedding plane surface.  In addition, numerous perpendicular structures represent activity by "worms". 
mike

REFERENCES CITED 

Cox, L. J. and R. A., Beach 1980, Status of Mineral Resource Information for the Lower Brule Indian Reservation, South Dakota: Bureau of Indian Affairs Report 74.

Hewett, D. F., 1930, Manganese-iron Carbonate near Chamberlain, South Dakota: U. S. Geological Survey Memorandum for the Press, February 5, 1930 (noted in Cox and Beach, 1980).



MANGANESE NODULES AND THE MANGANESE-RICH ZONE, PIERRE SHALE



REMAINS OF THE OLD MANGANESE MINE WEST OF CHAMBERLAIN

COLLECTING AT THE GATOROSA

SMOKY HILL JASPER

Rockhounds seeking interesting minerals for their cabinets, or looking for specimens to cut and polish, often blaze across Kansas to better “picking grounds”.  However, they may be overlooking numerous collecting possibilities.

In western Kansas the Miocene Ogallala Formation crops out at many localities.   This unit, consisting of stream gravels, along with a few volcanic ash beds and lake deposits, represents debris shed off the rising and eroding Rocky Mountains to the west, as well as fragments of local Cretaceous rocks.  As such, these outcrops contain a wide variety of minerals that originally formed in igneous rocks of the mountains.  The problem in collecting such minerals is that the Ogallala outcrops are commonly consolidated and tightly cemented and many times are covered by younger wind-blown sediments.

The answer to locating interesting minerals, and one that collectors commonly overlook, is to examine sand and gravel deposits situated along the major river systems, especially the Republican, Arkansas, Smoky Hill, and Saline, in the western part of the state.  These rivers have cut through and eroded the Ogallala and underlying Niobrara formations and then deposited their load (as current drops in velocity) in flood plains and channels.  Today these Pleistocene sediments are often well-exposed in numerous sand and gravels “pits” found on the older terraces.   If these excavations are not available for searching, simply walk the stream beds.

I have found a variety of minerals in the gravels with the finest specimens being various shades of jasper ranging from red to orange to green to brown.  Some of these jasper specimens from along the Republican, Smoky Hill, and Saline rivers in northern Kansas represent silicified chalk from the Cretaceous Smoky Hill Chalk Member of the Niobrara Formation.  These jasper outcrops are scattered across northwestern Kansas and seem to represent a post-depositional enrichment of the chalk, possibly with some dissolution of the chalk, by ground water rich in silica.  The source of the silica—probably volcanic ash or bentonite (altered ash).

Petrified wood is fairly common and chalcedony occurs in a variety of colors.  Of additional interest are the “Kansas Diamonds”, pieces of rounded and egg-shaped crystalline quartz.  Feldspar fragments are numerous but seem much smaller in size that the various quartz minerals (~1 cm or less) and are generally angular (broken along cleavage planes).  In addition, sort of nondescript dark colored rocks with an obvious igneous source are locally abundant.

The quartz minerals derived from the Rocky Mountains are generally less than 5-6 cm and highly rounded as the transport distance is great.  The locally derived jasper may be large (up to 13 cm in my collections) and specimens are angular.

I have seen beautiful faceted specimens of quartz derived from “Kansas Diamonds” and when combined with silver settings are quite spectacular.  In addition, the jasper makes wonderful cabochons or just plain tumbled stones.  Native Americans often used the silicified chalk for projectile points and one see the terms Niobrarite or Smoky Hill Jasper used in the literature.

So, although gemstones and semi-precious gemstones are essentially non-existent in Kansas, the jasper, chalcedony, quartz  and petrified wood offer some nice specimens for the lapidariest or flintnapper. 

BTW, the Gatorosa is my brother's ranch along the Smoky Hill River in Trego, County!

mike 

LOCALLY DERIVED SMOKY HILL JASPER.  MANY SPECIMENS SHOW STRONG BANDING.

NON-LOCAL CHALCEDONY.

NON-LOCAL? CHALCEDONY.

SAND AND GRAVEL DEPOSIT ON THE "HIGH TERRACE" AT THE GATOROSA.  YUCCA PLANTS FOR SCALE.

ARTIFACTS CONSTRUCTED FROM SMOKY HILL JASPER.  PHOTO COURTESY OF DON BLAKESLEE AND KANSAS STATE HISTORICAL SOCIETY.

NOTCH PEAK: GREAT GEOLOGY

SHARP CONTACT BETWEEN METAMORPHOSED CAMBRIAN CARBONATES AND THE NOTCH PEAK INTRUSION.  IT IS NOT OFTEN THAT ONE CAN :PUT THEIR FINGER" ON SUCH A CONTACT

The House Range is one of those geological wonders found in the west desert of Utah and the Great Basin—it is a classic uplifted block of rocks, a horst, bounded by Tule and Sevier valleys, the grabens.  The Range is north-south trending (~40 mi X 7 mi) and generally exposes lower Paleozoic (Cambrian and Ordovician) rocks.  However, there is a major quartz monzonite (an igneous rock similar to granite but without the quartz) intrusive body of Jurassic age (Notch Peak Intrusion) called Sawtooth Mountain.  This name comes from the weathering of the monzonite into sharp points and ridges as compared to the more rounded peaks in the limestones and shales. 

NOTCH PEAK IN THE HOUSE RANGE.  THE PEAK IS CAPPED BY THE NOTCH PEAK DOLOMITE.  NOTE THE ORANGE-COLORED AND INTRUSIVE QUARTZ MONZANITE OF THE NOTCH PEAK INTRUSION.  PHOTO COURTESY OF WIKIPEDIA.

The dominant topographic feature of the Range is Notch Peak at 9654 feet, but with a vertical rise (cliff) of about 2200 feet at the summit.  The peak itself is floored by the Notch Peak Intrusion with overlying Cambrian and Ordovician carbonates and topped by the Notch Peak Dolomite. The igneous rocks have produced minor amounts of placer gold and some claims are still active.  It seems as though the source of the gold dust has never been located, perhaps representing an opportunity for prospectors to “strike it rich”!  One of the really “neat things” about the fascinating geology at Sawtooth Mountain is that one is able to “put your finger” on the contact between a major intrusive feature and a sedimentary rock and follow the metamorphic aureole outward.  This intrusive event is related to tectonic activity associated with the Nevadan Orogeny and is approximately 150 Ma in age. 

mike