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Minerva No. 1 Mine (Ozark-Mahoning No. 1 Mine), Ozark-Mahoning group, Cave-in-Rock, Cave-in-Rock Sub-District, Hardin Co., Illinois, USAi
Regional Level Types
Minerva No. 1 Mine (Ozark-Mahoning No. 1 Mine)Mine
Ozark-Mahoning group- not defined -
Cave-in-Rock- not defined -
Cave-in-Rock Sub-DistrictSubdistrict
Hardin Co.County

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Lock Map
Latitude & Longitude (WGS84): 37° 32' 36'' North , 88° 9' 23'' West
Latitude & Longitude (decimal): 37.54321,-88.15634
GeoHash:G#: dn9m9fw90
Locality type:Mine
Köppen climate type:Cfa : Humid subtropical climate
Nearest Settlements:
Cave-in-Rock318 (2011)8.3km
Sturgis1,912 (2017)15.2km
Elizabethtown287 (2017)17.0km
Old Shawneetown178 (2017)17.2km
Shawneetown1,164 (2017)19.1km

The Minerva No. 1 Mine was a former zinc and fluorspar mine located north of Cave-in-Rock, Illinois. The mine was classified as a bedding replacement type mine (also known as a “manto”), that exploited the Cave-in-Rock orebody. The orebody, according to Alan Goldstein (1997) was approximately 20,000 feet long. It was also the largest bedding replacement orebody in the United States (Goldstein, 1997).

The Minerva Oil Company discovered the Minerva No. 1 orebody in 1940 (Goldstein, 1997), though exploration work officially began in 1939 (Weller et al. 1952). In 1942, a 645 foot shaft was sunk, named the “Ledbetter Shaft” and was finally completed in September 1943 (Weller et al., 1952). In 1949, the Minerva Oil Company decided to sink a second shaft, approximately 580 foot in depth, in 1949 to serve as a service and a possible escape route. The Minerva No. 1 Mine was the deepest operational mine in the Illinois-Kentucky Fluorspar District.

According to Alan Goldstein (1997), the southeast orebody was shallow and predominantly held sphalerite. At greater depths, fluorite became dominant. As mining progresses, inclined shafts needed to be built to access the Rosiclare and Sub-Rosiclare Levels where the fluorite was being mined. During times when the price of fluorspar was low, production resumed at the upper levels for zinc (Goldstein, 1997). The major orebody was also slightly tilted to the northeast, most likely because of its approximate location close to Hick’s Dome.

In February 1944, a differential flotation mill was constructed on site to handle ore. The mill produced hydrofluoric acid-grade concentrates, but also ceramic fluorspar concentrates as well. Concentrates from sphalerite revealed that it contained a very small percentage of cadmium as well, from .8 to 1 percent (Weller et al. 1952). Operation began later on the northeast portion of the orebody that same year.

In 1975, the Allied Chemical Corporation purchased the mine, but chose to shut down the operation in 1976. After a few years of being idle, the Inverness Mining Company in 1982 (itself a subsidiary of Seaforth Minerals and Ore Company)(Evans and Hellier, 1986, Goldstein, 1997), operated the Minerva No. 1 Mine until at least 1986 when it was sold to Ozark-Mahoning Mining Company in 1988 (Pennwalt Corporation purchased Ozark-Mahoning in 1974 and it remained a subsidiary of that company [Evans and Hellier, 1986]).

After Ozark-Mahoning purchased the mine, it needed to be dewatered, before operation could resume there. According to Eric Livingston, (personal communication to Alan Goldstein) an estimated 1 billion gallons of water needed to be removed before Ozark-Mahoning could resume mining. Mining resumed at the Minerva No. 1 Mine in 1989, which also received a name change to Ozark-Mahoning No. 1. Specimens recovered before Ozark-Mahoning resumed operation are labeled are typically labeled as “Minerva No. 1”, while specimens recovered during Ozark-Mahoning’s tenure of the mine are typically labeled as “Mahoning No. 1 or Ozark-Mahoning No. 1”. Under Ozark-Mahoning’s tenure of the property, several of the mine's best specimens were extracted during this time. The majority of these fluorite specimens came from the productive Rosiclare and Sub-Rosiclare Levels.

One of the most surprising finds for the Ozark-Mahoning Company included the Cross-Cut Ore Body. According to Ross Lillie (2010), the ore body was not on the plan map and no reserves were accounted for in this section of the mine. The ore was accidentally found by following a small exposure in an old drift that was left by previous mining. Instead of the ore thinning and typically running out, it persisted into uncharted territory neither mapped, nor drilled. It ultimately proved to be of enormous benefit to Ozark-Mahoning and lasted three to four years. The name ‘Cross-Cut’ was used since the mineralized zone transected at near right angles to the main Minerva trend.

The hallmark of this ore body was abundant hydrocarbons in the mineralized section that influenced everything from the formation of minerals to the milling process. In some localized sections, the hydrocarbons were so abundant it upset the effective recovery of fluorspar in the flotation mill.

Fluorite crystals were commonly formed in brown or pale yellow groups with highly distorted and etched morphology. However, in some cases there was a late-stage overgrowth of transparent, strikingly zoned fluorite on the early etched phase. The contrast of the glassy overgrowth with the distorted matrix formed exquisite specimens.

The best of these were found in one isolated pocket in September 1990 in a pocket coined ‘The Blue Cap Pocket’. Some two flats of specimens were recovered once and only of this color and combination. The minerals in the cross-cut ore body were mined from 1990-1994.

By 1995, Ozark-Mahoning realized that it was difficult to justify keeping the mine open when cheaper fluorite was available from China. During this time, “pillar robbing” of the Minerva No. 1 occurred between 1995 and 1996 and a small amount of specimens were once again available. On the last day of January 1996, Ozark-Mahoning finally decided to shut down the Minerva No. 1 Mine (Smith, 1996). Shortly thereafter the shaft and mill plant were both demolished.

Today the Minerva No. 1 Mine holds an important legacy for the Cave-in-Rock District and the Illinois-Kentucky Fluorspar District as a whole. Besides fluorite, the orebody produced excellent witherite, alstonite, benstonite, strontianite and baryte (Goldstein, 1997).

Regions containing this locality

North America PlateTectonic Plate
Illinois-Kentucky Fluorspar District, Illinois/Kentucky, USAMining District

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List

20 valid minerals. 1 (TL) - type locality of valid minerals.

Detailed Mineral List:

Formula: BaCa(CO3)2
Habit: sharpely terminated pseudo-hexagonal pyramids up to 2 mm in length
Colour: colorless to grey, transparent
Description: Lining cavities in veins of waxy benstonite, finegrained calcite and witherite crystals.
Reference: Rossman, G. R. and Squires, R. L. (1974) The occurence of alstonite at Cave in Rock, Illinois. Mineralogical Record 5: 266-269; Rocks & Minerals: 63: 214.; ; Mineralogical Record (1997) 28:3-49
Formula: PbSO4
Reference: Mineralogical Record (1997) 28:3-49
Formula: Cu3(CO3)2(OH)2
Reference: Rocks & Minerals: 63: 359.; Mineralogical Record (1997) 28:3-49
Formula: BaSO4
Reference: Rocks & Minerals: 63: 214-216.; Rocks & Min.: 63:210-226; Mineralogical Record (1997) 28:3-49
Formula: BaCa(CO3)2
Reference: Reiner Mielke 2017
Formula: Ba6Ca6Mg(CO3)13
Reference: Rocks & Minerals: 63: 217.; Mineralogical Record (1997) 28:3-49
Description: Crude oil in cavities
Reference: Mineralogical Record (1997) 28:3-49
Formula: CaCO3
Reference: [www.johnbetts-fineminerals.com]; Rocks & Min.: 63:210-226; Mineralogical Record (1997) 28:3-49; P Haas collection
Formula: SrSO4
Reference: Mineralogical Record (1997) 28:3-49
Formula: CuFeS2
Reference: Rocks & Minerals: 63: 221.; Econ Geol (1994) 89:288-306
Formula: CaMg(CO3)2
Reference: Mineralogical Record (1997) 28:3-49
Formula: CaF2
Reference: Rocks & Minerals: 63: 359.; Econ Geol (1994) 89:288-306; Rocks & Min.: 63:210-226; Mineralogical Record (1997) 28:3-49; P Haas collection
Formula: PbS
Reference: Econ Geol (1994) 89:288-306
Formula: CaSO4 · 2H2O
Reference: Goldstein, A. (2005): Re-examination of some minerals from the Cave-in-Rock area. Mineral News, 21(4), 1-5; 12. ; Mineralogical Record (1997) 28:3-49
Formula: Zn4Si2O7(OH)2 · H2O
Reference: Goldstein, A. (2005): Re-examination of some minerals from the Cave-in-Rock area. Mineral News, 21(4), 1-5; 12.
Formula: Cu2(CO3)(OH)2
Reference: Rocks & Minerals: 63: 359.; Mineralogical Record (1997) 28:3-49
Paralstonite (TL)
Formula: BaCa(CO3)2
Type Locality:
Reference: A. C. Roberts (1979) Paralstonite, a new mineral from the Minerva no. 1 mine, Cave-in-Rock, Illinois. Geol. Surv. Can. Pap.,79-lC, 99-100.; Mineralogical Record (1997) 28:3-49
Formula: SiO2
Reference: Goldstein, A. (2005): Re-examination of some minerals from the Cave-in-Rock area. Mineral News, 21(4), 1-5; 12. ; Mineralogical Record (1997) 28:3-49
Formula: ZnS
Reference: U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.; Econ Geol (1994) 89:288-306; Mineralogical Record (1997) 28:3-49
Formula: SrCO3
Reference: Rocks & Minerals: 63: 221.; Mineralogical Record (1997) 28:3-49
Reference: Mineralogical Record (1997) 28:3-49
Formula: BaCO3
Habit: Complex tapered prismatic
Colour: White, off-white.
Fluorescence: Bright creamy-white (LW & SW UV)
Description: World class specimens, including single crystals to 4 inches (10 cm) long.
Reference: Mineralogical Record: 5: 266-269; Rocks & Minerals: 63: 221.; Mineralogical Record (1997) 28:3-49

List of minerals arranged by Strunz 10th Edition classification

Group 2 - Sulphides and Sulfosalts
Group 3 - Halides
Group 4 - Oxides and Hydroxides
Group 5 - Nitrates and Carbonates
Paralstonite (TL)5.AB.40BaCa(CO3)2
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
Gypsum7.CD.40CaSO4 · 2H2O
Group 9 - Silicates
Hemimorphite9.BD.10Zn4Si2O7(OH)2 · H2O
Unclassified Minerals, Rocks, etc.

List of minerals arranged by Dana 8th Edition classification

Group 2 - SULFIDES
AmXp, with m:p = 1:1
AmBnXp, with (m+n):p = 1:1
Paralstonite (TL)
Gypsum29.6.3.1CaSO4 · 2H2O
Group 56 - SOROSILICATES Si2O7 Groups, With Additional O, OH, F and H2O
Si2O7 Groups and O, OH, F, and H2O with cations in [4] coordination
Hemimorphite56.1.2.1Zn4Si2O7(OH)2 · H2O
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Unclassified Minerals, Mixtures, etc.

List of minerals for each chemical element

H AzuriteCu3(CO3)2(OH)2
H MalachiteCu2(CO3)(OH)2
H GypsumCaSO4 · 2H2O
H HemimorphiteZn4Si2O7(OH)2 · H2O
C ParalstoniteBaCa(CO3)2
C WitheriteBaCO3
C CalciteCaCO3
C StrontianiteSrCO3
C AlstoniteBaCa(CO3)2
C AzuriteCu3(CO3)2(OH)2
C MalachiteCu2(CO3)(OH)2
C BenstoniteBa6Ca6Mg(CO3)13
C DolomiteCaMg(CO3)2
C BarytocalciteBaCa(CO3)2
O ParalstoniteBaCa(CO3)2
O WitheriteBaCO3
O CalciteCaCO3
O BaryteBaSO4
O CelestineSrSO4
O StrontianiteSrCO3
O AlstoniteBaCa(CO3)2
O AzuriteCu3(CO3)2(OH)2
O MalachiteCu2(CO3)(OH)2
O BenstoniteBa6Ca6Mg(CO3)13
O AnglesitePbSO4
O GypsumCaSO4 · 2H2O
O QuartzSiO2
O HemimorphiteZn4Si2O7(OH)2 · H2O
O DolomiteCaMg(CO3)2
O BarytocalciteBaCa(CO3)2
F FluoriteCaF2
Mg BenstoniteBa6Ca6Mg(CO3)13
Mg DolomiteCaMg(CO3)2
Si QuartzSiO2
Si HemimorphiteZn4Si2O7(OH)2 · H2O
S GalenaPbS
S SphaleriteZnS
S BaryteBaSO4
S CelestineSrSO4
S ChalcopyriteCuFeS2
S AnglesitePbSO4
S GypsumCaSO4 · 2H2O
Ca ParalstoniteBaCa(CO3)2
Ca CalciteCaCO3
Ca FluoriteCaF2
Ca AlstoniteBaCa(CO3)2
Ca BenstoniteBa6Ca6Mg(CO3)13
Ca GypsumCaSO4 · 2H2O
Ca DolomiteCaMg(CO3)2
Ca BarytocalciteBaCa(CO3)2
Fe ChalcopyriteCuFeS2
Cu AzuriteCu3(CO3)2(OH)2
Cu MalachiteCu2(CO3)(OH)2
Cu ChalcopyriteCuFeS2
Zn SphaleriteZnS
Zn HemimorphiteZn4Si2O7(OH)2 · H2O
Sr CelestineSrSO4
Sr StrontianiteSrCO3
Ba ParalstoniteBaCa(CO3)2
Ba WitheriteBaCO3
Ba BaryteBaSO4
Ba AlstoniteBaCa(CO3)2
Ba BenstoniteBa6Ca6Mg(CO3)13
Ba BarytocalciteBaCa(CO3)2
Pb GalenaPbS
Pb AnglesitePbSO4

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org

251.902 - 541 Ma

ID: 3187973
Paleozoic sedimentary rocks

Age: Phanerozoic (251.902 - 541 Ma)

Lithology: Sedimentary rocks

Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]

323.2 - 330.9 Ma

ID: 3006695
Upper Pope Group (Tar Springs Sandstone through Kinkaid Limestone)

Age: Mississippian (323.2 - 330.9 Ma)

Stratigraphic Name: Vienna Limestone; Waltersburg Formation; Menard Limestone; Palestine Sandstone; Clore Formation; Degonia Sandstone; Negli Creek Limestone; Cave Hill Shale Member; Goreville Limestone Member; Grove Church Shale Member

Description: According to the stratigraphic column, the Pope Group only occurs in southern Illinois (south of 40 degrees north latitude). The upper part of the Pope Group is comprised, from oldest to youngest, of the Tar Springs Sandstone (0-150’), Vienna Limestone (0-60’), Waltersburg Formation (0-100’), Menard Limestone (0-150’, includes the Walche Limestone, Scottsburg Limestone, and Allard Limestone Members), Palestine Sandstone (0-120’), Clore Formation (0-150’, includes the Cora Limestone, Tygett Sandstone, and Ford Station Limestone Members), Degonia Sandstone (0-150’), and Kinkaid Limestone (0-230’, includes the Negli Creek Limestone, Cave Hill Shale, Goreville Limestone, and Grove Church Shale Members).

Comments: Original map source: Kolata, D.R., comp., 2005, Bedrock Geology of Illinois: Champaign, Ill., Illinois State Geological Survey, Illinois Map Series 14, scale 1:500,000.

Lithology: Major:{limestone,sandstone,shale}

Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. [133]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License


Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Weller, J.M., Grogan, R.M., and Tippie, F.E. (1952) Geology of the fluorspar deposits of Illinois. Illinois State Geological Survey, Bulletin 76: 1-147.
Brecke, E.A. (1962) Ore genesis of the Cave-in-Rock Fluorspar District, Hardin County, Illinois, Economic Geology: 57 (4): 499-535.
Baxter, J.W., Potter, P.E., and Doyle, F.L. (1963) Areal geology of the Illinois fluorspar district, Part 1, Saline Mines, Cave in Rock, Dekoven, and Repton Quadrangles. Illinois State Geological Survey, Circular 342: 1-43.
Rossman, G. R. and Squires, R. L. (1974) The occurrence of alstonite at Cave in Rock, Illinois. The Mineralogical Record: 5 (6): 266-269.
Evans, V.A., and Hellier, D.L. (1986) Case study; Ozark-Mahoning, sole surviving US fluorspar producer. Mining Engineering Journal: 38 (11): 1030-1032.
Lillie, R.C. (1988) Minerals of the Harris Creek Fluorspar District, Hardin County, Illinois. Rocks and Minerals: 63 (3): 210-226.
Goldstein, A. (1997) The Illinois-Kentucky fluorspar district, The Mineralogical Record: 28 (1): 3-49.
Denny, F.B, Devera, J.A., and Kittler, A. (2013) Bedrock Geology of Saline Mines Quadrangle, Gallatin and Hardin Counties, Illinois. Illinois State Geological Survey, Illinois Geologic Quadrangle Map, IGQ Saline Mines-BG: 1-10.

External Links

Smith, W., 1996, Mine closures deal a blow to Illinois. The Chicago Tribune, http://articles.chicagotribune.com/1996-01-31/news/9601310250_1_fluorspar-mining-illinois

Lillie, R.C. in Sadlocha, S., 2010, The cross-cut orebody of the Minerva Mine. http://www.mindat.org/photo-341110.html

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