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Conrad Hill Mine (Dodge Hill Mine), Cid District, Carolina Slate Belt, Davidson Co., North Carolina, USAi
Regional Level Types
Conrad Hill Mine (Dodge Hill Mine)Mine
Cid DistrictMining District
Carolina Slate BeltBelt
Davidson Co.County
North CarolinaState
USACountry

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Key
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Latitude & Longitude (WGS84):
35° 47' 5'' North , 80° 9' 55'' West
Latitude & Longitude (decimal):
Locality type:
Köppen climate type:
Nearest Settlements:
PlacePopulationDistance
Lexington19,326 (2017)9.1km
Washington Park439 (2017)9.6km
Thomasville27,061 (2017)13.2km
Welcome4,162 (2017)15.5km
Southmont1,470 (2017)15.9km


A former Au occurrence/mine. The abandoned mine has been wooded for decades and is now largely overgrown. Earlier owners were receptive to collectors but not currently.

Mineralization is a vein deposit. The veins are largely quartz with about 40% coarse, cleavable, red-brown to brown siderite, cellular and mammillary goethite, and a sericitic phyllite that is not indigenous to the country rock.

Workings include underground openings comprised of a shaft and adit. A sinuous incline shaft follows the ore vein down at about a 45 degree angle. Two major vertical shafts and numerous other smaller excavations are scattered about.

Regions containing this locality

North America PlateTectonic Plate

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List


12 valid minerals. 2 erroneous literature entries.

Detailed Mineral List:

Ankerite
Formula: Ca(Fe2+,Mg)(CO3)2
Description: There is no ankerite at Conrad Hill. The carbonate is overwhelmingly siderite, and no calcium is present in the geochemistry. A myth of calling pseudomorphs of goethite after calcite rhombs "ankerite" became widespread at the Hiddenite localities in Alexander County, and this myth likely spread here since similar pseudomorphs after siderite occur here.
Reference: USGS Prof Paper 610 "Principal Gold Producing Districts of the United States"; Steve Adams Luttrell,Gwendoly W.. (1978) Gold,base-metal,and related deposits of North Carolina :USGS Open File Report 78-152 pg.97
Brochantite
Formula: Cu4(SO4)(OH)6
Description: Brochantite does not occur at Conrad Hill. I (Steve Adams) have not observed brochantite at this mine after half a century collecting there. I have regularly observed acicular malachite. The mine is very rich in carbonate but appears completely lacking in sulfates. Cited references do not mention brochantite.
Reference: Carpenter III, P. Albert (1976) Metallic Mineral Deposits of the Carolina Slate Belt, North Carolina : NCGS Bulletion 84 pg.23
Chalcopyrite
Formula: CuFeS2
Description: Chalcopyrite was the principle ore mineral at the Conrad Hill Mine. It was auriferous. The mine produced significant gold for a few decades in the early 1900's with accessory production of copper. Most of both came from the chalcopyrite, although grains of native gold dust contributed. The chalcopyrite is in spots and splotches in the quartz/siderite matrix rock of the ore body. Some of it is iridescent. Crystals, if they even exist, are exceedingly rare.
Reference: USGS Prof Paper 610 "Principal Gold Producing Districts of the United States"
'Chlorite Group'
Description: The chlorite is in small flakes and crude crystals on milky quartz and sometimes impregnating the quartz. Decent small specimens with crystallized quartz are found occasionally.
Reference: Pogue,J.E.,(1910) The Cid district of Davidison County,North Carolina, former Steve Adams collection.
Cuprite
Formula: Cu2O
Description: The mine often has red ocherous hematite, but dense maroon masses associated with chalcopyrite and malachite long inspired my suspicion that they were at least in part cuprite. The presence of the mineral finally became confirmed when I observed a specimen in the collection of Guilford College from a field trip they took there in the 1960's. There were small patches of poor acicular "chalcotrichite" variety cuprite on a piece of cellular goethite. The mineral should be considered rare and of poor quality. I myself collected a micro later of very tiny red crystals on quartz - not impressive.
Reference: Guilford College Collection, former Steve Adams collection
Goethite
Formula: α-Fe3+O(OH)
Description: Was recorded as Limonite. The identity of goethite as the species is visually quite obvious. The mineral occurs in two major modes. The main interest in goethite here is the black mammillary masses. Very nice cabinet display pieces were relatively common half a century ago (1960's) but are hard to come by now. The other mode is brown cellular cavity-ridden pseudomorphs after siderite retaining some of the rhombic orientation in the walls of cavities. The interest here is finding nice malachite crystals in the vugs. Furthermore, nice rhombic pseudomorphs of goethite after siderite crystals are somewhat common. A lot of the quartz at the mine has drusy crystal surfaces richly impregnated by goethite, making attractive sparkly brown pieces.
Reference: Pogue,J.E.,(1910)The Cid mining district of Davidison County,North Carolina:North Carolina Geological and Economic Survey Bulletin #22; Steve Adams
Gold
Formula: Au
Description: Most of the gold produced at the Conrad Hill Mine came from auriferous chalcopyrite. However, disseminated small grains of native gold contributed. Very rarely, pinhead size grains are found embedded in cellular goethite rock. Laurie Adams collected such a piece now in the Kenny Gay collection.
Reference: U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
Hematite
Formula: Fe2O3
Description: Hematite takes two modes at Conrad Hill: red ochre and black coarse platy. The platy is best described as "platy hematite" and does not resemble the variety "specularite". Tiny crystals are very rare and unimpressive, but they have been found. I (Steve Adams) found a few pieces with such crystals over many years of collecting there.
Reference: Luttrell,Gwendoly W.,(1978)Gold,base-metal,and related deposits of North Carolina :USGS Open File Report 78-152 pg.97 : Wilson,W.F and McKenzie,B.J (1980) Mineral Collecting Sites in North Carolina pg.30
Hematite var: Specularite
Formula: Fe2O3
Description: Hematite takes two modes at Conrad Hill: red ochre and black coarse platy. The platy is not aptly descriptive as "specularite". The material does not resemble the sparkly compact variety specularite and should be called platy hematite.
Reference: Pogue,J.E.,(1910) The Cid district of Davidison County,North Carolina, Steve Adams
Malachite
Formula: Cu2(CO3)(OH)2
Description: Malachite is common as small patches and stains, often with chalcopyrite. But within the void spaces of the cellular goethite, nice acicular crystals and silky or velvety sprays can be found with diligence. In the 1970's I (Steve Adams) broke open a piece of such goethite and was astonished to see a spray of several needles of malachite fine as a hair rising from a point a full inch tall! But holding it up in admiration, a strong wind gust came along and broke the crystals away!
Reference: U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia., Steve Adams
Muscovite
Formula: KAl2(AlSi3O10)(OH)2
Description: The listing of muscovite as a mineral at Conrad Hill can be misleading. What is present is a very fine grained sericite "schist" according to the literature, but certainly a phyllite. There are no visible mica flakes under a 15x hand lens. The rock resembles a creamy pale beige or greenish beige serpentine. It creates patches along with milky quartz and coarse cleavages of red-brown siderite. This combination makes attractive "yard rocks". Note that this rock is confined to the ore body and is absent in the country rock.
Reference: Steve Adams
Muscovite var: Sericite
Formula: KAl2(AlSi3O10)(OH)2
Description: See comments under muscovite. This is a very fine-grained phyllite with "sericite" as the primary constituent. No mica flakes can be seen under a hand lens.
Reference: Carpenter III, P. Albert (1976) Metallic Mineral Deposits of the Carolina Slate Belt, North Carolina : NCGS Bulletion 84
Pyrite ?
Formula: FeS2
Description: One tends to think that pyrite would have to be at this mine. But in half a century of collecting I (Steve Adams) have seen none that I could be sure is pyrite and not chalcopyrite. See notes on chalcopyrite, the major ore mineral of the mine, which seems to be the only sulfide present.
Reference: U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia. Steve Adams
Pyrite var: Auriferous Pyrite
Formula: FeS2
Description: See notes under pyrite. If pyrite actually is present, it would likely be auriferous. The chalcopyrite is definitely auriferous, which in fact made the mine profitable.
Reference: Pogue,J.E.,(1910) The Cid district of Davidison County,North Carolina, Steve Adams
Quartz
Formula: SiO2
Description: Milky quartz is abundant as a gangue mineral in the dump material, typically making nice contrast to siderite. Vugs and seams often have small crystals, rarely very clear. Drusy quartz surfaces are often impregnated with goethite making sparkling brown specimens. Much more rarely the quartz is chloritic.
Reference: USGS Prof Paper 610 "Principal Gold Producing Districts of the United States", Steve Adams
Siderite
Formula: FeCO3
Description: Very coarse cleavage masses of siderite comprise up to 40% of the gangue in the dump material. Single cleavage rhombs of ten centimeters across have been extracted. Intergrown red-brown coarse cleavage masses are plentiful and often attractive, especially with contrasting milky quartz. Often the quartz has seams and vugs of small crystals, and very sharp siderite crystals frequently occur with them. Habits are usually rhombs but also blades. Cavities directly in the siderite masses can show dull rhombs, often crude, up to three centimeters across. Finally, cellular brown goethite pseudomorphs after siderite rhombic crystals are fairly common. Single masses of siderite can weigh over a hundred pounds.
Reference: U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.; Steve Adams

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
Gold1.AA.05Au
Group 2 - Sulphides and Sulfosalts
Chalcopyrite2.CB.10aCuFeS2
Pyrite ?2.EB.05aFeS2
var: Auriferous Pyrite ?2.EB.05aFeS2
Group 4 - Oxides and Hydroxides
Cuprite4.AA.10Cu2O
Goethite4.00.α-Fe3+O(OH)
Hematite4.CB.05Fe2O3
var: Specularite ?4.CB.05Fe2O3
Quartz4.DA.05SiO2
Group 5 - Nitrates and Carbonates
Ankerite5.AB.10Ca(Fe2+,Mg)(CO3)2
Malachite5.BA.10Cu2(CO3)(OH)2
Siderite5.AB.05FeCO3
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
Brochantite7.BB.25Cu4(SO4)(OH)6
Group 9 - Silicates
Muscovite9.EC.15KAl2(AlSi3O10)(OH)2
var: Sericite9.EC.15KAl2(AlSi3O10)(OH)2
Unclassified Minerals, Rocks, etc.
'Chlorite Group'-

List of minerals arranged by Dana 8th Edition classification

Group 1 - NATIVE ELEMENTS AND ALLOYS
Metals, other than the Platinum Group
Gold1.1.1.1Au
Group 2 - SULFIDES
AmBnXp, with (m+n):p = 1:1
Chalcopyrite2.9.1.1CuFeS2
AmBnXp, with (m+n):p = 1:2
Pyrite ?2.12.1.1FeS2
Group 4 - SIMPLE OXIDES
A2X
Cuprite4.1.1.1Cu2O
A2X3
Hematite4.3.1.2Fe2O3
Group 6 - HYDROXIDES AND OXIDES CONTAINING HYDROXYL
XO(OH)
Goethite6.1.1.2α-Fe3+O(OH)
Group 14 - ANHYDROUS NORMAL CARBONATES
A(XO3)
Siderite14.1.1.3FeCO3
AB(XO3)2
Ankerite14.2.1.2Ca(Fe2+,Mg)(CO3)2
Group 16a - ANHYDROUS CARBONATES CONTAINING HYDROXYL OR HALOGEN
Malachite16a.3.1.1Cu2(CO3)(OH)2
Group 30 - ANHYDROUS SULFATES CONTAINING HYDROXYL OR HALOGEN
(AB)m(XO4)pZq, where m:p>2:1
Brochantite30.1.3.1Cu4(SO4)(OH)6
Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings
Sheets of 6-membered rings with 2:1 layers
Muscovite71.2.2a.1KAl2(AlSi3O10)(OH)2
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Unclassified Minerals, Mixtures, etc.
'Chlorite Group'-
Hematite
var: Specularite ?
-Fe2O3
Muscovite
var: Sericite
-KAl2(AlSi3O10)(OH)2
Pyrite
var: Auriferous Pyrite ?
-FeS2

List of minerals for each chemical element

HHydrogen
H MalachiteCu2(CO3)(OH)2
H Goethiteα-Fe3+O(OH)
H BrochantiteCu4(SO4)(OH)6
H Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
H MuscoviteKAl2(AlSi3O10)(OH)2
CCarbon
C MalachiteCu2(CO3)(OH)2
C SideriteFeCO3
C AnkeriteCa(Fe2+,Mg)(CO3)2
OOxygen
O MalachiteCu2(CO3)(OH)2
O SideriteFeCO3
O Goethiteα-Fe3+O(OH)
O QuartzSiO2
O AnkeriteCa(Fe2+,Mg)(CO3)2
O HematiteFe2O3
O BrochantiteCu4(SO4)(OH)6
O CupriteCu2O
O Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
O MuscoviteKAl2(AlSi3O10)(OH)2
O Hematite (var: Specularite)Fe2O3
MgMagnesium
Mg AnkeriteCa(Fe2+,Mg)(CO3)2
AlAluminium
Al Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
Al MuscoviteKAl2(AlSi3O10)(OH)2
SiSilicon
Si QuartzSiO2
Si Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
Si MuscoviteKAl2(AlSi3O10)(OH)2
SSulfur
S ChalcopyriteCuFeS2
S BrochantiteCu4(SO4)(OH)6
S PyriteFeS2
S Pyrite (var: Auriferous Pyrite)FeS2
KPotassium
K Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
K MuscoviteKAl2(AlSi3O10)(OH)2
CaCalcium
Ca AnkeriteCa(Fe2+,Mg)(CO3)2
FeIron
Fe SideriteFeCO3
Fe Goethiteα-Fe3+O(OH)
Fe ChalcopyriteCuFeS2
Fe AnkeriteCa(Fe2+,Mg)(CO3)2
Fe HematiteFe2O3
Fe PyriteFeS2
Fe Hematite (var: Specularite)Fe2O3
Fe Pyrite (var: Auriferous Pyrite)FeS2
CuCopper
Cu MalachiteCu2(CO3)(OH)2
Cu ChalcopyriteCuFeS2
Cu BrochantiteCu4(SO4)(OH)6
Cu CupriteCu2O
AuGold
Au GoldAu

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

Cambrian - Neoproterozoic
485.4 - 1000 Ma



ID: 2953646
Phyllite and Schist

Age: Neoproterozoic to Cambrian (485.4 - 1000 Ma)

Description: Locally laminated and pyritic; includes phyllonite, sheared fine-grained metasediment, and metavolcanic rock. In Lilesville granite aureole, includes hornfels.

Comments: In the description of CZph on the printed map, there is a unit called CZph1 and it applies to the hornfels of the Lilesville granite aureole. On the digital map this unit is NOT used, only CZph. So I did NOT make a separate unit for CZph1. The digital map DOES use the unit CZbg (which is described under CZph on the printed map also), so I DID make this a separate unit. Original map source: The North Carolina Dept. of Environment, Health, and Natural Resources, Division of Land Resources, NC Geological Survey, in cooperation with the NC Center for Geographic Information and Analysis, 1998 (updated 2007), Geology - North Carolina (1:250,000)

Lithology: Major:{phyllite,schist}, Minor:{phyllonite}, Incidental:{metasedimentary, metavolcanic, hornfels}

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]

Cambrian - Neoproterozoic
485.4 - 1000 Ma



ID: 3184289
Precambrian-Phanerozoic sedimentary and volcanic rocks

Age: Neoproterozoic to Cambrian (485.4 - 1000 Ma)

Comments: Carolina Slate Belt

Lithology: Sedimentary and volcanic 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]

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

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Pogue, J.E. (1910) The Cid mining district of Davidison County, North Carolina, North Carolina Geological and Economic Survey Bulletin 22.
Murdock, T. G. (1948) The Mining Industry in North Carolina from 1945, North Carolina Department of Conservation and Development, Economic Paper No. 65: 8-10.
Koschmann, A.H. and M.H. Bergendahl (1968) Principal Gold Producing Districts of the United States, USGS Professional Paper 610.
Carpenter III, P. Albert (1976) Metallic Minerals Deposits of the Carolina Slate Belt, North Carolina. North Carolina Department of Natural Resources and Community Development, Division of Land Resources, Geological Survey Section Bulletin 84, map at 1:125,000: 46, mine text p. 4.
Ballard, T.J. and Clayton, A.B. (1948) Conrad Hill Copper and Gold Deposit, Davidson County, N.C. Report of Investigations, United States Department of the Interior - Bureau of Mines, R.I.4290.
Pratt, J. H., The Mining Industry in North Carolina.


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