Vote for your favorite mineral in #MinCup26! - Sphalerite vs. Anorthite
Both zinc ore Sphalerite and calcium plagioclase feldspar Anorthite have perfect cleavage that will split cleanly if you hit them with a hammer, but only one can claim a larger split of your votes!
Log InRegister
Quick Links : The Mindat ManualThe Rock H. Currier Digital LibraryMindat Newsletter [Free Download]
Home PageAbout MindatThe Mindat ManualHistory of MindatCopyright StatusWho We AreContact UsAdvertise on Mindat
Donate to MindatCorporate SponsorshipSponsor a PageSponsored PagesMindat AdvertisersAdvertise on Mindat
Learning CenterWhat is a mineral?The most common minerals on earthInformation for EducatorsMindat ArticlesThe ElementsThe Rock H. Currier Digital LibraryGeologic TimeExplore Fossils
Minerals by PropertiesMinerals by ChemistryMineral Visual ExplorerAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
Mining CompaniesStatisticsUsersMineral MuseumsClubs & OrganizationsMineral Shows & EventsThe Mindat DirectoryDevice SettingsThe Mineral QuizTime Machine
Photo SearchPhoto GalleriesSearch by ColorPhoto Colour ExplorerNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day GalleryPhotography

Berkshire Mine (Pioneer Mine; Hoppenyan exploration), Mount Whittlesey, Gogebic Range, Ashland County, Wisconsin, USAi
Regional Level Types
Berkshire Mine (Pioneer Mine; Hoppenyan exploration)Mine
Mount WhittleseyMountain
Gogebic RangeMountain Range
Ashland CountyCounty
WisconsinState
USACountry

This page is currently not sponsored. Click here to sponsor this page.
PhotosMapsSearch
Latitude & Longitude (WGS84):
46° 17' 60'' North , 90° 37' 0'' West
Latitude & Longitude (decimal):
46.30000,-90.61667
GeoHash:
G#: cbpx3uwvn
GRN:
N31W46
Type:
Mine
Köppen climate type:
Dfb : Warm-summer humid continental climate
Nearest Settlements:
PlacePopulationDistance
Mellen700 (2017)4.4km
Glidden507 (2017)18.6km
Marengo111 (2017)20.5km
Birch Hill293 (2017)25.0km
Iron Belt173 (2017)25.1km
Mindat Locality ID:
25700
Long-form identifier:
mindat:1:2:25700:9
GUID (UUID V4):
0


Mine site ruins and outcrop on the west flank of Mt. Whittlesey in Sec 9 T44N R2W. Thick to thin bedded iron minerals and chert, typical banded iron formation. Due to the proximity of the Mellen igneous complex, the rocks have experienced relatively high grade contact metamorphism, with grunerite and magnetite reported as the dominant iron minerals. The deposit was initially developed as the Hoppenyan exploration in 1886-1887, when shafts were dug. The property was sold to the Pioneer Mining Company in 1917,and was worked as an open pit, shipping ore in 1922-1924. Recent attempts to open a new and enormous open pit iron mine in the area have not yet been realized (2015).

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Mineral List


11 valid minerals.

Detailed Mineral List:

ⓘ Almandine
Formula: Fe2+3Al2(SiO4)3
ⓘ Ankerite
Formula: Ca(Fe2+,Mg)(CO3)2
ⓘ Chamosite
Formula: (Fe2+,Mg,Al,Fe3+)6(Si,Al)4O10(OH,O)8
ⓘ Chamosite var. Thuringite
Formula: (Fe,Fe,Mg,Al)6(Si,Al)4O10(O,OH)8
ⓘ 'Chlorite Group'
ⓘ Dolomite
Formula: CaMg(CO3)2
ⓘ 'Garnet Group'
Formula: X3Z2(SiO4)3
ⓘ Goethite
Formula: Fe3+O(OH)
ⓘ Grunerite
Formula: ◻{Fe2+2}{Fe2+5}(Si8O22)(OH)2
ⓘ Hematite
Formula: Fe2O3
ⓘ Magnetite
Formula: Fe2+Fe3+2O4
ⓘ Quartz
Formula: SiO2
ⓘ Siderite
Formula: FeCO3
ⓘ Talc
Formula: Mg3Si4O10(OH)2

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
ⓘGoethite4.00.Fe3+O(OH)
ⓘMagnetite4.BB.05Fe2+Fe3+2O4
ⓘHematite4.CB.05Fe2O3
ⓘQuartz4.DA.05SiO2
Group 5 - Nitrates and Carbonates
ⓘSiderite5.AB.05FeCO3
ⓘAnkerite5.AB.10Ca(Fe2+,Mg)(CO3)2
ⓘDolomite5.AB.10CaMg(CO3)2
Group 9 - Silicates
ⓘAlmandine9.AD.25Fe2+3Al2(SiO4)3
ⓘGrunerite9.DE.05◻{Fe2+2}{Fe2+5}(Si8O22)(OH)2
ⓘTalc9.EC.05Mg3Si4O10(OH)2
ⓘChamosite9.EC.55(Fe2+,Mg,Al,Fe3+)6(Si,Al)4O10(OH,O)8
ⓘvar. Thuringite9.EC.55(Fe,Fe,Mg,Al)6(Si,Al)4O10(O,OH)8
Unclassified
ⓘ'Chlorite Group'-
ⓘ'Garnet Group'-X3Z2(SiO4)3

List of minerals for each chemical element

HHydrogen
Hⓘ Chamosite(Fe2+,Mg,Al,Fe3+)6(Si,Al)4O10(OH,O)8
Hⓘ GoethiteFe3+O(OH)
Hⓘ Grunerite◻{Fe22+}{Fe52+}(Si8O22)(OH)2
Hⓘ TalcMg3Si4O10(OH)2
Hⓘ Chamosite var. Thuringite(Fe,Fe,Mg,Al)6(Si,Al)4O10(O,OH)8
CCarbon
Cⓘ AnkeriteCa(Fe2+,Mg)(CO3)2
Cⓘ DolomiteCaMg(CO3)2
Cⓘ SideriteFeCO3
OOxygen
Oⓘ AnkeriteCa(Fe2+,Mg)(CO3)2
Oⓘ AlmandineFe32+Al2(SiO4)3
Oⓘ Chamosite(Fe2+,Mg,Al,Fe3+)6(Si,Al)4O10(OH,O)8
Oⓘ DolomiteCaMg(CO3)2
Oⓘ GoethiteFe3+O(OH)
Oⓘ Grunerite◻{Fe22+}{Fe52+}(Si8O22)(OH)2
Oⓘ HematiteFe2O3
Oⓘ MagnetiteFe2+Fe23+O4
Oⓘ QuartzSiO2
Oⓘ SideriteFeCO3
Oⓘ TalcMg3Si4O10(OH)2
Oⓘ Chamosite var. Thuringite(Fe,Fe,Mg,Al)6(Si,Al)4O10(O,OH)8
Oⓘ Garnet GroupX3Z2(SiO4)3
MgMagnesium
Mgⓘ AnkeriteCa(Fe2+,Mg)(CO3)2
Mgⓘ Chamosite(Fe2+,Mg,Al,Fe3+)6(Si,Al)4O10(OH,O)8
Mgⓘ DolomiteCaMg(CO3)2
Mgⓘ TalcMg3Si4O10(OH)2
Mgⓘ Chamosite var. Thuringite(Fe,Fe,Mg,Al)6(Si,Al)4O10(O,OH)8
AlAluminium
Alⓘ AlmandineFe32+Al2(SiO4)3
Alⓘ Chamosite(Fe2+,Mg,Al,Fe3+)6(Si,Al)4O10(OH,O)8
Alⓘ Chamosite var. Thuringite(Fe,Fe,Mg,Al)6(Si,Al)4O10(O,OH)8
SiSilicon
Siⓘ AlmandineFe32+Al2(SiO4)3
Siⓘ Chamosite(Fe2+,Mg,Al,Fe3+)6(Si,Al)4O10(OH,O)8
Siⓘ Grunerite◻{Fe22+}{Fe52+}(Si8O22)(OH)2
Siⓘ QuartzSiO2
Siⓘ TalcMg3Si4O10(OH)2
Siⓘ Chamosite var. Thuringite(Fe,Fe,Mg,Al)6(Si,Al)4O10(O,OH)8
Siⓘ Garnet GroupX3Z2(SiO4)3
CaCalcium
Caⓘ AnkeriteCa(Fe2+,Mg)(CO3)2
Caⓘ DolomiteCaMg(CO3)2
FeIron
Feⓘ AnkeriteCa(Fe2+,Mg)(CO3)2
Feⓘ AlmandineFe32+Al2(SiO4)3
Feⓘ Chamosite(Fe2+,Mg,Al,Fe3+)6(Si,Al)4O10(OH,O)8
Feⓘ GoethiteFe3+O(OH)
Feⓘ Grunerite◻{Fe22+}{Fe52+}(Si8O22)(OH)2
Feⓘ HematiteFe2O3
Feⓘ MagnetiteFe2+Fe23+O4
Feⓘ SideriteFeCO3
Feⓘ Chamosite var. Thuringite(Fe,Fe,Mg,Al)6(Si,Al)4O10(O,OH)8

Other Regions, Features and Areas containing this locality

North AmericaContinent
North America PlateTectonic Plate
USA

This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.

References

Van Hise, C. R. & Irving, R. (1892) The Penokee iron-bearing series of northern Wisconsin and Michigan: U.S.Geological Survey Monograph 19, 634 pp.
Laybourn, D.P. (1979) Geology and metamorphism of the Ironwood Iron Formation, Gogebic Range, Wisconsin: Master of Science thesis University of Minnesota- Duluth, 223 p.
LaBerge, G. (1979) Stop 2 - Mount Wittlesey- Ironwood Iron Formation, in Mudrey, M. edited, Middle Precambrian geology of northern Wisconsin: Wisconsin Geological and Natural history Survey Field trip guidebook 4: 15-19.
Cox, B. (2005) Mines of the Pewabic Country of Michigan and Wisconsin: vol. 3 Wisconsin Iron: Agogebic Press: 52-53.
Cannon, W. , G. LaBerge, J. Klasner & K. Schulz (2007) The Gogebic Iron Range - a sample of the northern margin of the Penokean fold and thrust belt: U. S. Geological Survey Professional Paper 1730, 44 p. plus map.
Quick NavTopMineral ListOther RegionsReferences
 
and/or  
Mindat.org® is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization. Mindat® and mindat.org® are registered trademarks of the Hudson Institute of Mineralogy.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2026, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph and Ida Chau.
Content on this site may not be used to train, fine-tune, or otherwise develop artificial intelligence or machine learning models without prior written permission - see our Terms & Conditions.
To cite: Ralph, J., Von Bargen, D., Martynov, P., Zhang, J., Que, X., Prabhu, A., Morrison, S. M., Li, W., Chen, W., & Ma, X. (2025). Mindat.org: The open access mineralogy database to accelerate data-intensive geoscience research. American Mineralogist, 110(6), 833–844. doi:10.2138/am-2024-9486.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: September 3, 2026 11:02:33 Page updated: August 9, 2025 15:16:52
Go to top of page