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Bok Asbestos Mine, Hollofield, Baltimore Co., Maryland, USAi
Regional Level Types
Bok Asbestos MineMine
Hollofield- not defined -
Baltimore Co.County
MarylandState
USACountry

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Key
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Latitude & Longitude (WGS84): 39° 19' 5'' North , 76° 47' 17'' West
Latitude & Longitude (decimal): 39.31806,-76.78806
GeoHash:G#: dqcrstssk
Locality type:Mine
Köppen climate type:Cfa : Humid subtropical climate
Nearest Settlements:
PlacePopulationDistance
Milford Mill29,042 (2011)3.7km
Woodlawn37,879 (2011)5.2km
Randallstown32,430 (2011)5.5km
Ellicott City65,834 (2011)5.7km
Lochearn25,333 (2011)6.2km


In partially amphibolized layered gabbro and pyroxenite. Rock is part of the Baltimore Mafic Complex. Bernstein reports anthophyllite fibers up to 15 cm long recoverable from the old dumps.

Regions containing this locality

North America PlateTectonic Plate

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.


Mineral List


5 valid minerals.

Detailed Mineral List:

Actinolite
Formula: ☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Reference: pubs.usgs.gov/of/2005/1189/downloads/asbestos_sites.xls
Anthophyllite
Formula: ☐{Mg2}{Mg5}(Si8O22)(OH)2
Reference: USGS Bull 1082K
'Chlorite Group'
Reference: USGS Bull 1082K
Magnetite
Formula: Fe2+Fe3+2O4
Reference: pubs.usgs.gov/of/2005/1189/downloads/asbestos_sites.xls
Talc
Formula: Mg3Si4O10(OH)2
Reference: USGS Bull 1082K
Tremolite
Formula: ☐{Ca2}{Mg5}(Si8O22)(OH)2
Reference: pubs.usgs.gov/of/2005/1189/downloads/asbestos_sites.xls

List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
Magnetite4.BB.05Fe2+Fe3+2O4
Group 9 - Silicates
Actinolite9.DE.10☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Anthophyllite9.DD.05☐{Mg2}{Mg5}(Si8O22)(OH)2
Talc9.EC.05Mg3Si4O10(OH)2
Tremolite9.DE.10☐{Ca2}{Mg5}(Si8O22)(OH)2
Unclassified Minerals, Rocks, etc.
'Chlorite Group'-

List of minerals arranged by Dana 8th Edition classification

Group 7 - MULTIPLE OXIDES
AB2X4
Magnetite7.2.2.3Fe2+Fe3+2O4
Group 66 - INOSILICATES Double-Width,Unbranched Chains,(W=2)
Amphiboles - Mg-Fe-Mn-Li subgroup
Anthophyllite66.1.2.1☐{Mg2}{Mg5}(Si8O22)(OH)2
Tremolite66.1.3a.1☐{Ca2}{Mg5}(Si8O22)(OH)2
Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings
Sheets of 6-membered rings with 2:1 layers
Talc71.2.1.3Mg3Si4O10(OH)2
Unclassified Minerals, Mixtures, etc.
Actinolite-☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
'Chlorite Group'-

List of minerals for each chemical element

HHydrogen
H Anthophyllite☐{Mg2}{Mg5}(Si8O22)(OH)2
H TalcMg3Si4O10(OH)2
H Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
H Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
OOxygen
O Anthophyllite☐{Mg2}{Mg5}(Si8O22)(OH)2
O MagnetiteFe2+Fe23+O4
O TalcMg3Si4O10(OH)2
O Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
O Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
MgMagnesium
Mg Anthophyllite☐{Mg2}{Mg5}(Si8O22)(OH)2
Mg TalcMg3Si4O10(OH)2
Mg Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Mg Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
SiSilicon
Si Anthophyllite☐{Mg2}{Mg5}(Si8O22)(OH)2
Si TalcMg3Si4O10(OH)2
Si Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Si Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
CaCalcium
Ca Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Ca Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
FeIron
Fe MagnetiteFe2+Fe23+O4
Fe Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2

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

Paleozoic - Proterozoic
251.902 - 2500 Ma



ID: 2720256
Baltimore Gabbro Complex

Age: to Triassic (251.902 - 2500 Ma)

Stratigraphic Name: Baltimore Gabbro Complex

Description: Hypersthene gabbro with subordinate amounts of olivine gabbro, norite, anorthositic gabbro, and pyroxenite; igneous minerals and textures well preserved in some rocks, other rocks exhibit varying degrees of alteration and recrystallization with a new metamorphic mineral assemblage.

Comments: Original map source: In 1995 the Water Resources Division of the U.S. Geological Survey digitized the geologic map of Maryland from the 1968 paper map (Reference MD001). Information about products from the Maryland Geological Survey can be found at http://www.mgs.md.gov/.

Lithology: Major:{gabbro}, Minor:{norite,pyroxenite}

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]

Mesoproterozoic
1000 - 1600 Ma



ID: 3193072
Mesoproterozoic crystalline metamorphic rocks

Age: Mesoproterozoic (1000 - 1600 Ma)

Lithology: Orthogneiss

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)
Pearre, N. & A. V. Heyl (1960) Mineral deposits in serpentine rocks of the Piedmont Upland, Maryland, Pennsylvania and Delaware: U. S. Geological Survey: Bulletin 1082K: 707-833.
Bernstein, Lawrence (1980) Minerals of the Washington D. C. area: Maryland Geological Survey Educational Series 5, 148 p.


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