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Howard Co., Maryland, USA
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Except for a band of unconsolidated Cretaceous rock along its eastern edge (essentially the I-95 corridor), Howard County is underlain by metamorphic and igneous rocks of the Piedmont Province. They are intruded by several generations of granite and pegmatites, as well as bodies of maifc rock from the Baltimore Gabbro Complex. Several domes, most notably the Woodstock Dome near Marriottsville, bring up the oldest rock in Maryland, the 1.0 to 1.3 billion year old Baltimore Gneiss. The gneiss is surrounded by Cambrian quartzite, marble and schist. These are well exposed along the Patapsco River, on the border with Baltimore County. Development has restricted access to or obliterated many of the occurrences, however the diversity of the geology means that any new excavation is worth exploring for new mineral occurrences.

Mineral List

Mineral list contains entries from the region specified including sub-localities
Actinolite
Albite
var: Oligoclase
'Albite-Anorthite Series'
'Allanite'
Anthophyllite
'Apatite'
Autunite
Beryl
'Biotite'
Calcite
Chalcopyrite
'Chlorite Group'
Clinozoisite
'Columbite'
Diopside
Dolomite
Dravite
Epidote
'Feldspar Group'
Ferro-hornblende
Fluorapatite
Gahnite
Galena
'Garnet'
Gold
Hematite
var: Specularite
'Hornblende'
Ilmenite
'K Feldspar'
'var: Adularia'
Kyanite
'Limonite'
Mackinawite
Magnetite
Malachite
Microcline
Muscovite
var: Sericite
Nontronite
'Olivine'
Orthoclase
Phlogopite
Pyrite
Pyrophyllite
Pyrrhotite
Quartz
var: Amethyst
var: Rock Crystal
var: Rutilated Quartz
Quartz
var: Smoky Quartz

Rutile
'Scapolite'
Schorl
Sillimanite
Spessartine
Staurolite
'Stilbite'
Talc
'Tantalite'
Titanite
Tremolite
Vermiculite
Zircon


65 entries listed. 42 valid minerals.

Localities in this Region

USA
USA

The above list 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

Ostrander, C. W. & W. E. Price (1940) Minerals of Maryland: Natural History Society of Maryland , 92 p.

Cloos, E. et. al. (1964) Howard and Montgomery Counties, Maryland: Maryland Geological Survey: County Report: 373 p.

Crowley, W. P. et. al. (1971) New interpretations of the eastern Piedmont geology of Maryland: Maryland Geological Survey, Guidebook Series 2, 32 p.

Bernstein, Lawrence (1980) Minerals of the Washington D. C. area: Maryland Geological Survey Educational Series 5, 148 p.

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Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
Current server date and time: September 2, 2014 09:15:08 Page generated: August 20, 2014 00:52:31
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