Barry County | Central Missouri Barite and Lead District | Christian County | Greene County |
Hickory County | Lead-Zinc in Southwest Missouri outside the Tri-State District |
Mine La Motte and Fredericktown | Old Lead Belt | Other Lead-Zinc in Southeast Missouri |
Southeast Missouri | Tri-State District Southwest Missouri | Viburnum Trend |
Washington County Barite District

Barry County
Lead and zinc mining in Barry County occurred primarily in the 1880s through 1890s, with some production in the 1910s, 1930s and 1940s (IMOP database).  There was likely unrecorded production in the 1930s.  The primary lead and zinc mining area was the Purdy mines area, located east of the town of Purdy.  The mines are hosted by limestones of the Mississippian Osagean Series.  The McDowell mines are the only ones specifically noted to have a mill on-site.

Central Missouri Barite and Lead District
Lead was the principal product of the Central Missouri Lead and Barite District from 1830 to 1910; there was also minor zinc production.  After 1910 the district produced barite with lead as a by-product (Kiilsgaard et al, 1967; Brobst and Wagner, 1967).  Production ended in the 1950s.  The district includes all or portions of Morgan, Miller, Camden, Moniteau, Cooper and Cole counties.  Numerous deposits of barite, lead and zinc were produced.  The district is located on the northwest flank of the Ozark uplift in Ordovician, Mississippian, and Pennsylvanian rocks which are fairly flat-lying to slightly folded. 

Ore grade varied from deposit to deposit, as well as within deposits.  Mineralization was found as vein and fracture fill, breccia cement, solution channel and "pocket" fill, replacement of host rocks, filled sinkholes, and as a residual material (Brobst and Wagner, 1967).  In many cases the old lead pits were used as an exploration guide for barite mining, and led to considerable recovery of the remaining galena.  In addition to galena and barite, the ores contain some copper as chalcopyrite, malachite and azurite (copper oxides).  The barite contains up to two percent strontium.

Christian County
The primary lead and zinc mining areas for Christian County are Elk Valley mines (including Alma mines) south of Ozark, Finley Creek mines northeast of Ozark, Burkhart or Swan Creek mines east of Sparta and the Turkey Creek mines southeast of Chadwick (Winslow, 1894b).  Lead and zinc mining in Christian County occurred primarily in the 1850s through the 1890s, with some production in the 1910s, 1920s and 1930s (IMOP database). Shepard (1898) noted considerable mining in the area.  The 1870 census noted no mining in that year, but mining was resumed soon after (Winslow, 1894b).  The Monarch and Mary Arnold mining companies had minor production through World War II (Clark, 1945; Ballinger, 1948a, 1948b).

The Elk Valley and northern Finley Creek mine areas are hosted by the Burlington-Keokuk Limestone.  Deposits at the Swan Creek and Turkey Creek mine areas are hosted by the Jefferson City-Cotter dolomites.

The Robertson Mining Company separated ore with hand jigs and constructed a 150 ton mill (Missouri State Mine Inspector, 1918; Buehler, 1919).  The Bray Mining Company operated a 100 ton mill (Missouri State Mine Inspector, 1918; Buehler 1919) and the Bull Creek Mining Company operated a 60 ton mill (Missouri State Mine Inspector, 1916, 1917; Buehler 1919); Bull Creek separated ore with a hand jig.  The Ozark Mining Company used steam jigs and operated a 100 ton concentrating plant (Missouri State Mine Inspector, 1901, 1917; Buehler, 1919).  The Alma Mining Company (Missouri State Mine Inspector, 1902) and the San Toy Mining Company (Missouri State Mine Inspector, 1918) also operated mills.  C.D. Bray and Price & Bray constructed an operating furnace on Bull Creek by 1857 (Swallow, 1859; Winslow, 1894a).

Greene County
Lead and zinc production in Greene County was from four main areas:  Ash Grove, Brookline, Pickerel Creek and Pierson Creek.  European use of mineralization in the Pierson Creek Area began in 1819, when Henry Rowe Schoolcraft noted lead in the area of the future Phelps Mine.  The lead had been used previously for production of bullets by American Indians and early European settlers.  In 1844, former Governor McClurg mined and smelted ore in the area of the Phelps Mine, near the James River.  The next development occurred in 1858, when mining expanded in the Pierson Creek area.  Major production began in 1875; it was originally dominated by Charles and Henry Sheppard and Judge Picher (Phelps property), and continued on this site until 1891.  The Pierson Creek mines operated intermittently until around 1920, when mining in the area ceased (Thomson, 1986).  An attempt to reopen the Phelps mine in 1956 did not succeed economically (Melton, 1978).

Discovery of galena in a well south of Ash Grove in 1859 spurred activity in that area, with increased production beginning in 1867.  A smelter was also constructed at that time.  The Pennsylvania Company opened a shaft in 1891 and operated it until 1893.  Most production in this area ended by 1898 (Thomson, 1986).  The H & H Mining Company briefly opened a mine in 1948; records indicate minor production in 1948 and no production in 1949 (Missouri State Mine Inspector, 1948, 1949).

Production near Brookline began in 1873; it dropped to low levels in 1876.  Final production occurred around 1898.  A smelter was erected in 1876, but was abandoned after a few years (Missouri State Mine Inspector, 1892).  Production in the Pickerel Creek area began in 1887 and continued until around 1898 (Thomson, 1986).

Ore minerals were as noted above.  Pyromorphite (lead phosphate), anglesite (lead sulfate), pyrolusite (manganese oxide) and greenockite (cadmium sulfide) were also present, but noted as not in mineable quantities. (Shepard, 1898; Melton, 1978; Thomson, 1986).

The deposits at Ash Grove, Brookline and Pickerel Creek are hosted by the Burlington-Keokuk Limestone.  Deposits at Pierson Creek are hosted by the Northview, Compton and Bachelor formations.  There is considerable structural control on the ore.  Mineralization is associated with northwest-trending subparallel fractures and faults.

Steam jigs are commonly noted in the Pierson Creek mines area, where they were useful in removal of the ore from clay.  Shepard (1898) notes that at the Pierson Creek mines, the process of removing the ore from the clay “requires 2,000 gallons of water per minute.  The water is pumped from the creek, and is used only once.”

Hickory County
Lead and zinc production in Hickory County was concentrated in an area east and south of the town of Hermitage and east and west of Cross Timbers.  The majority of lead/zinc mining occurred during the 1890s through the 1910s.  Barite was produced in the early 1930s and mid 1940s (U.S. Bureau of Mines, 1931, 1933, 1944) with the last known production during the early 1960s.  Lead was produced as a by-product of barite production.

Ores mined in the Cross Timbers area was hauled to Warsaw or Linn Creek for processing, while ores mined near Hermitage were taken to Collins to be processed (Winslow, 1894a, 1894b; State Mine Inspector, 1902).  Lack of rail and other shipping facilities slowed development in this area (Winslow, 1894b; State Mine Inspector, 1902).  By 1901, construction had begun on a mill at Pittsburg, in the southeast part of Hickory County (State Mine Inspector, 1902).

The deposits are primarily hosted by the Jefferson City/Cotter dolomites, with some deposits hosted by the Burlington-Keokuk Limestone. 

Early production was as noted above.  Later production would have involved mechanical stripping of surface materials and drilling and blasting of bedrock material.  Material would have been processed through a mill or washer (if barite) for separation from waste rock.  Waste material would have been piled near the mine site.  Mill tailings would have been impounded or dumped near the mill site.

Marbut (1892) noted a smelter in operation in Hickory County in 1876, and indicated that the information came from History of Missouri by Davis & Durrie, p. 373.  An internet search suggested this book is “An Illustrated History of Missouri Comprising Its Early Record, and Civil, Political, and Military History from the First Exploration to the Present Time: Including an Encyclopedia of Legislation During the Administrations of the Governors from M'Nair, 1820, to Hardin, 1876, with the Topography ...” by Walter Bickford Davis and Daniel S. Durrie, published by A.J. Hall and Co, 1876.  This resource was not available to collect further information about this smelter.

Lead-Zinc in Southwest Missouri outside the Tri-State District
Lead was first mined in Greene, Webster, and Christian counties in the 1850s.  Most mining in southwest Missouri from the 1870s to the 1940s was in these three counties plus Taney, Ozark, Wright, Dade, Howell and Texas counties.  The periods of highest production were from 1858 to 1918 and during World War I.  Production for individual mines was generally less than 10,000 tons of lead and zinc concentrate combined; a few areas produced up to or over 20,000 tons.  The Stotts Creek deposits (Lawrence County) produced as much as 500,000 tons of ore; the Pierson Creek deposits (Greene County) are estimated to have produced over 400,000 tons.  Larger camps are noted below by county, other mines were produced primarily by individuals and by farmers working mines during the winter.  Ore was sold directly to smelters in the area.

Production was from Mississippian- and Ordovician-aged units; the majority of the production was from Mississippian-hosted mineralization.  Surficial lead-zinc deposits in much of southwest Missouri were similar to the surface and near-surface ores in Washington County.  Much of the ore was in clay residuum and near surface bedrock (disseminated and fracture fill), and could be mined by hand-mining techniques.  Subsurface deposits in Mississippian rocks were similar to, although smaller than, those in Tri-State.  Runs are found in Mississippian deposits; small sheet-ground deposits, breccias, and circles occur in the cherty zones above the runs.  Ordovician-hosted ore was along faults, in breccia zones, filled fractures and replaced host rock.

Ore minerals were galena (lead sulfide), cerussite (lead carbonate), sphalerite (zinc sulfide), smithsonite (zinc carbonate), barite (barium sulfate) and hemimorphite (zinc silicate).  Chalcopyrite (copper iron sulfide) and malachite (copper carbonate) are present but not in mineable quantities.  Gangue minerals include calcite, dolomite, marcasite, pyrite, chalcopyrite, limonite and chert (IMOP database).  Carbonate, phosphate and sulfate minerals were more common in the float and residual ores, where weathering process dominated.

Lead and zinc mining in these areas was by both surface and underground mining methods.  Known depths of underground operations range up to 220 feet in depth; other operations may have been deeper.  Ore processing was done with a combination of crushers, rollers and hand-operated and steam-operated jigs.  Some production would have been by hand mining and cleaning.

Mine La Motte and Fredericktown
Lead was discovered north of Fredericktown (Madison County) in 1720.  The mine was active intermittently until it closed in 1959 having produced more than 325,000 tons of lead metal.  A number of mines were worked around Fredericktown from the 1860s until 1961.  National Lead Company operated the most productive mines - located southeast of the town - as well as a surface plant (Kiilsgaard, et al, 1967).

Ores were generally shallow - usually 250 to 400 feet from the surface.  Deposits were relatively flat-lying, sinuous lenses up to 40 feet thick, 50 to 250 feet wide and several hundred feet long; ore was restricted to the lower 50 feet of the Bonne Terre Formation and the upper 15 feet of the La Motte Sandstone (Snyder and Gerdemann, 1968).

Old Lead Belt
The Old Lead Belt encompassed Bonne Terre, Desloge, Park Hills, Doe Run and Leadwood (predominantly St. Francois County, with small operations in Washington and Madison counties).  Between 1864 and 1972, St. Joe operated numerous lead/zinc mines and mills in the area.  During the first 70 years as many as 14 other companies operated in the Old Lead Belt, including ASARCO, St. Louis Smelting and Refining (later National Lead) and Flat River Lead Company.  By the mid-1930s, St. Joe owned all competing operations (Kiilsgaard, et al, 1967).

In 1864 drilling led to discovery of deeper ores and underground mining began.  Underground mining occurred in Bonne Terre from 1864 to 1961, at Doe Run from 1887 to 1914, in Desloge from 1929 to 1958 and at Leadwood from 1915 to 1962.  The final operation, at Park Hills, closed in 1972.  St. Joe opened a lead smelter at Herculaneum in 1891; its main smelting operations have been based there continuously.

Galena was the primary ore mineral.  Ore was found in the La Motte down to 100 feet below the contact with the Bonne Terre, and throughout the 400-foot thick Bonne Terre.  Mineralization was disseminated in favorable parts of the Bonne Terre, with galena replacing dolomite; ore was also found at bedding-plane contacts, in fracture zones and as breccia cement.  Ore bodies spread laterally hundreds of feet and vertically up to 200 feet.

Total production figures for the Old Lead Belt are not readily available, however, more than 8.5 million tons of lead metal alone were produced (Wharton, 1975).

Southeast Missouri
Lead has been mined in southeast Missouri since before 1700, when French explorers developed deposits under land grants from the French crown.  Lead has been produced from Mississippi Valley-type deposits, or MVT's, in several world-class districts: the Old Lead Belt, Mine La Motte and Fredericktown and the Viburnum Trend.  The Washington County Barite District, which once led the world in barite production, has also been a significant lead producer.  The entire region is sometimes referred to as the Southeast Missouri Lead District.  Lead-zinc-barite mineralization occurs in every formation from the upper Cambrian La Motte Sandstone to the lower Ordovician Jefferson City Formation, the youngest formation present in the region.  Missouri has been the leading producer of lead in the United States for well over a century and has also been the world's leading producer.

Early mining in the entire southeast Missouri area was of oxidized ores, primarily the lead carbonate mineral cerussite.  Mining moved onto galena when the more easily smelted cerussite was depleted.   Numerous small mines produced as much as 1,500 pounds a day of ore.  Mining was from small surface pits and shallow shafts, often with tens of pits or shafts in a small area.  In the Potosi area, Moses Austin erected the first reverberatory furnace, and by 1802 was smelting ore for the entire Potosi region, tripling the yield per pound.  Other discoveries made during this time led to lead mining in what are now Washington, Jefferson, Madison and St. Francois counties.

Most lead mining prior to 1869 was from scattered and shallow workings above the water table.  Workings were generally small and closely packed to recover the maximum amount of ore. 

In 1864 the St. Joseph Lead Company purchased lands in the vicinity of the town of Bonne Terre, which contained rich deposits of galena at or near the surface.  This area became known as the Lead Belt, later called the Old Lead Belt.

Declining Old Lead Belt reserves led to exploration in the early 1950s on the northern and western margins of the St. Francois Mountains.  The Indian Creek deposit was discovered north of the St. Francois Mountains in 1948 by St. Joe, and began production in 1953.  St. Joe drilled the discovery hole for the Viburnum Trend in 1955, with initial production in mid-1960.  Further exploration led to the opening of the 45-60 mile-long ore trend.  The last mine in the Old Lead Belt ceased operation in 1972; Indian Creek closed in 1982.

Other Lead-Zinc in Southeast Missouri
Several subdistricts in southeast Missouri also produced lead and zinc.  The Indian Creek and Goose Creek subdistrict produced lead from the Indian Creek Mine from 1954 to 1982.  The deposits are unique in that a significant part of the ore was in the La Motte Sandstone; major mineralization was still in the Bonne Terre.  Sandstone-hosted ores are more acidic than those hosted by carbonate rocks.

The Valle Mines zinc area, located in southern Jefferson County and extending into Ste. Genevieve and Washington counties, began production in 1824 and was most active from the late 1800s to 1917.  With the exception of dump material shipped during World War II, Valle Mines has been inactive since 1917.  Ore was mined from shallow workings generally less than 200 feet deep; smithsonite (zinc oxide) was the most common ore.  Lead minerals were included in dump material and would have experienced weathering.

The Irondale (Washington County) and Annapolis (Iron County) deposits were concentrated around igneous knobs.  Mineralization at Irondale was similar to that in the Old Lead Belt; galena at Annapolis occurred in a small cavity of dolomite near the Bonne Terre-Precambrian contact.

Hayden Creek mine, located near Irondale in Washington County, produced galena from granite conglomerate beds located where the Bonne Terre dolomite and La Motte sandstone pinch out against a Precambrian knob.

Tri-State District Southwest Missouri
The Tri-State District of southwest Missouri was a world-class producer of zinc and lead.  The Missouri portion of the district extends 55 miles east from the Kansas border to eastern Lawrence County, and 30 miles north-south from Neosho (Newton County) to the north fork of the Spring River (about 12 miles north of Joplin, in Jasper County).  Lesser satellite deposits extend as far as Wright, Douglas, and Ozark counties (Kiilsgaard, et al, 1967).

Early mining was oxidized ores, generally mined from ground surface to a depth of 75 feet.  The first major discovery in 1851 led to development of literally thousands of small mines.  Lead was the only metal recovered until 1872.  In a few years, there were 17 zinc furnaces running around the clock (Kiilsgaard, et al, 1967).  Zinc became the dominant metal product.  The Missouri portion of the district closed in 1957; the entire district closed by 1970.

The first lead mining was approximately two miles east of Joplin at Leadville in 1848.  The Granby area was the largest Missouri producer, and was active from 1850‑1870; the discovery of ore in 1870 in Joplin was the starting point in the district's growth to national prominence.  Record production in Missouri was in 1916, with 155,527 tons of zinc and 30,827 tons of lead, with a value of $46 million dollars, produced (Kiilsgaard, et al, 1967).

Early mining was on a lease and royalty system.  Landowners divided land into claims generally 200 feet square or as small as 100 square feet.  Miners would lease and develop the claims.  Companies also leased from landowners and then subleased for an advance royalty.  This leasing method remained prominent through the 1890s, and persisted into the 1930s (Kiilsgaard, et al, 1967).

Miners would dig shafts, sometimes as small as 3 by 4 feet, and mine what could be reached above the water table.  They would then sink another shaft, continuing the process until all available ore was mined.  Generally, ore deeper than 150 to 200 feet required more modern pumping methods.  Many deposits were shallow and limited in size, and were generally unproductive after 5 to 10 years.  The small, independently operated milling and smelting plants would then move to a new location, making it difficult today to locate sites of former operations. This leasing and mining system led to numerous small independent operators using inefficient mining and milling methods (Kiilsgaard, et al, 1967).  It also led to numerous chat and waste rock piles scattered about the region.  The Joplin area alone contains hundreds of shafts and pits and up to 4.6 square miles of chat and tailings piles.

Early production used a Joplin-type mill, which separated 90 percent of the lead, but had poor sphalerite recovery.  Flotation milling methods were introduced in 1924.  Completion of a rail spur in 1870 allowed shipping of ores to smelters in St. Louis.  The first zinc works in Missouri were in West Joplin in 1881, and in Rich Hill in 1882 (Kiilsgaard, et al, 1967).

The majority of the ore is in the Mississippian Burlington-Keokuk and Warsaw Formations.  The underlying Chattanooga shale is largely absent in the district, and ore mineralization is more intense when less than 10 feet of the underlying Northview shale is present (Brockie, et al, 1968).

Structure in the District is characterized by parallel, evenly-spaced northwesterly trending folds that pitch to the northwest.  Mineralization was largely in the synclinal portions of the folds.  In areas without folding, ore was almost always in nearly vertical shear zones (Brockie, et al, 1968).

Lead and zinc carbonates (cerussite and smithsonite) and zinc silicates (hemimorphite) were mined from shallow diggings in the early history of the district.  Greenockite, a cadmium sulfide, or CdS, mineral associated with the sphalerite as thin yellow-green coatings, was recovered during World War II (Kiilsgaard, et al, 1967).  Sphalerite was the primary zinc mineral, and contained minor amounts of germanium, gallium, and cadmium.  Galena was disseminated in jasperoid and dolomite, and also occurred as crystals.  Pyrite occurred as small crystals and grains in jasperoid, chert, dolomite, limestone and on pink dolomite in small cavities (Brockie, et al, 1968).

Ore bodies varied in shape from irregular, relatively narrow long bodies (runs), to circular bodies (circles), and flat-lying or tabular bodies with considerable areal extent (sheet-grounds).

Runs were the most important ore producers.  They varied from 10 to 500 feet in width, 5 to greater than 100 feet in height, and from a few hundred to several thousand feet in length.  Runs were associated with fractures or shear zones, as well as with extreme silicification of the host rocks and strong brecciation (Brockie, et al, 1968).

Circles were truncated cones in shape.  They were relatively shallow and associated with sinkholes in which Pennsylvanian shales were deposited.  Small ones were often mined using underground methods.  During the 1930s and 1940s, large circle deposits were open‑pitted; the most famous are Oronogo Circle and Sucker Flats (Brockie, et al, 1968).

Sheet-ground bodies were 12 to 15 feet thick and extended from 40 to 200 acres areally.  Ore minerals were in horizontal layers 0.5 to 4 inches thick interbedded with chert layers 6- to 12-inches thick.  The ore was hosted in broken ground resulting from slight folding and fracturing of the chert (Brockie, et al, 1968).

Viburnum Trend
The Viburnum Trend, located in Crawford, Washington, Iron, Dent, Reynolds and Shannon counties, produces lead, zinc, copper and silver.

With depletion of ore reserves in the Old Lead Belt, exploration for new deposits of lead and zinc began in the early 1950s.  St. Joe drilled the discovery hole for the Viburnum Trend in 1955 near the town of Viburnum.  The first ore from the new district was shipped from St. Joe's Number 27 mine in Crawford County in mid-1960.

The majority of the ore is disseminated in dolomite; it is also found filling void spaces as breccia cement and crystals, and as replacement on bedding planes.  Ore bodies generally trend north-south and are tabular to sinuous.  The average depth to ore is 1,200 feet.  Deposits average 30 to 85 feet thick and have a width of 200 to 2,000 feet.  Individual mines range from 20 to more than 50 million tons in size, and contain up to eight percent galena and several percent sphalerite.

Washington County Barite District
The Washington County Barite District encompasses most of Washington County and adjacent parts of St. Francois, Jefferson and Franklin counties, including the Potosi-Shirley-Palmer area.  Barite and galena occur in fractured bedrock and in red clay residuum weathered from the Potosi and Eminence dolomites; most galena was exposed to an oxidizing environment.  Barite and galena in veins and small isolated residual deposits is associated with the Gasconade dolomite in northeastern Washington County and southeastern Franklin County.  The deposits have associated limonite, pyrite and sphalerite; considerable galena was recovered from the district before barite mining and as a by-product.

Mining was often done by farmers who operated small mines during the winter to supplement their income.  In 1818, H.R. Schoolcraft noted of the Potosi area that there were a great number of "old diggings" in the area (Winslow, 1894).  In the early 1900s, several thousand people mined galena and barite in Washington County.  Small pits and hand mining gave way in 1924 to mechanized mining.  Barite mining boomed in 1926, when it began to be used in oil drilling mud; this also increased production of associated galena.  Washington County led the nation and world in barite production for a number of years.  Production started to decline in 1985, primarily due to overseas competition (Seeger, 1997, USDA Forest Service, 1999).  There is currently no barite production in Missouri.

Lead was mined both from residuum and from shafts extending into the bedrock. The majority of the barite mined was processed from residuum.  The residuum is often capped at the surface by layers of barren soil that range from several inches to three to four feet thick.  The average thickness of ore-bearing residuum is variable, but generally ranges from a few feet to over 30 feet in thickness (Seeger, 1997, USDA Forest Service, 1999).

Mineralization in the sample areas is the result of a district-wide mineralizing event.  Bodies of mined ore were often defined by availability of land, rather than by the extent of potentially economic ore.  Cessation of mining also created artificial boundaries on the edges of mineralization.  The scattered nature of the small mines found between later large ones is likely an artifact of the mining method, rather than due to discontinuities of the ore.  Older underground mining required minimum spacing of the shafts to allow stability of the mines.

Until shortly after 1900, barite and galena production was by hand mining and cleaning.  Most mining was in small pits and shafts sunk into residuum, and that sometimes penetrated bedrock.  Mining tools were a pick, a wooden shovel and a sledge hammer.  Ore was raised in buckets, hand-cobbed (hand-separated) from surrounding rock, and cleaned of clay by shaking in a rattle box.  Galena fines would have remained in the clay.  Careful spacing of pits and shafts allowed recovery of a fourth to a half of the barite and galena available (Wharton, 1972).  The first note of mechanization was by Schoolcraft in 1819, when a drill was used for blasting (Winslow, 1894).

By the late 1800s, a greater number of mines penetrated the bedrock at depths of 100 feet or greater (Winslow, 1894).  In some deeper mines, vertical crevices were seen to extend from the mine level to the surface of the bedrock. The crevices were originally clay-filled (Winslow, 1894), however, this material was removed during mining of the ore in the crevice.

In 1904, the Point Mining and Milling Company used an early steam shovel and wet-process mill (Wharton, 1972).  Hand mining, however, remained the dominant method until 1924.

Around 1924, the Eagle-Picher Company and National Pigments and Chemical Company began production with mechanically stripping residuum and processing the material in a washer and jig plant.  Bedrock was not mined.  Over-sized material was still broken by hand.  Jig washers were used to remove the clay after which the material was crushed and separated using a jig or concentration table.  A jig shakes the material and separates it by weight; the lighter clay, gravel and dolomite are concentrated separately from the denser barite and galena.  However, galena fines would have remained with the clay and gone to tailings ponds.  The galena was then separated by hand from the barite.  Due to severe unemployment in Washington County, most operations returned to hand mining by 1931; mechanized mining returned in by 1942 (Wharton, 1973).

After 1942, mechanized mining utilized shovels and front-end loaders.  Only residuum was mined and processed; no bedrock was mined.  Residuum was loaded into trucks and hauled to the washer where clay was removed with high pressure water in a rotary breaker.  At this point, the barite began to break from the other rock, and also began to be broken into smaller pieces.  It then passed through log washers (parallel counter-rotating cylinders with protruding inter-meshing paddles) that removed more clay and further broke the barite, or trommels (a rotating screen or sieve), and onto the jigs, where the barite and galena were separated from any remaining waste rock (Wharton, 1972).  The majority of the waste material that was not placed into tailings ponds was in filled into the existing pit; large tailings piles were generally not created.  Some small tailings piles were generated by later mining.  Again, the processing method lost galena fines into the clays and tailings ponds.

Many of the later large mining operations reworked lands that had experienced hand mining for lead or barite, as considerable barite ore remained in the material left between the pits and shafts.  In some cases, the older pits were used as an exploration guide.