Help mindat.org|Log In|Register|
Home PageMindat NewsThe Mindat ManualHistory of MindatCopyright StatusManagement TeamContact UsAdvertise on Mindat
Donate to MindatSponsor a PageSponsored PagesTop Available PagesMindat AdvertisersAdvertise on MindatThe Mindat Store
Minerals by PropertiesMinerals by ChemistryRandom MineralSearch by minIDLocalities Near MeSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
StatisticsThe ElementsMember ListBooks & MagazinesMineral Shows & EventsThe Mindat DirectoryHow to Link to MindatDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery

Rockport, Essex Co., Massachusetts, USA

This page is currently not sponsored. Click here to sponsor this page.
 
Latitude & Longitude (WGS84): 42° 39' 20'' North , 70° 37' 13'' West
Latitude & Longitude (decimal): 42.6555555556, -70.6202777778


The town of Rockport was separated from Gloucester and incorporated in 1840. Granite was quarried here beginning in 1823. Interesting minerals occur in granite quarries and other bedrock exposures of alkaline Cape Ann granite and associated pegmatites and miarolitic cavities.

McKinstry (1921) described some of the town's mineralogical highlights: "More than fifty years ago attention was called to the unusual mineral occurrences at Rockport, on Cape Ann, by J. P. Cooke's description of danalite, a new beryllium mineral, and subsequently of cryophyllite, a new lithium mica. Besides being the type locality for these species, the Rockport quarries have afforded an interesting list of rare-earth minerals, and, perhaps most unusual of all, large tabular crystals of fayalite, normally an utter stranger to granitic rocks."

Mineral List

Mineral list contains entries from the region specified including sub-localities

29 valid minerals. 2 (TL) - type locality of valid minerals.

Regional Geology

This 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 data will improve over time as more accurate maps and data sets are added.

Permian - Carboniferous252.17 - 358.9 MaCarboniferous-Permian sedimentary rocks

Sedimentary rocks

Silurian - Ordovician419.2 - 485.4 MaOrdovician-Silurian plutonic: undivided granitic rocks

Plutonic: undivided granitic rocks

Wenlock - Late Ordovician427.4 - 458.4 MaCape Ann Complex

Major:: {alkali-granite (alaskite)},Minor:: {quartz syenite}

Cape Ann Complex - Alkalic granite to quartz syenite containing ferro-hornblende. Intrudes Zdigb. Most of Cape Ann Complex forms Cape Ann peninsula of northeastern MA. Consists of alkalic granite to quartz syenite (its main phase), Beverly Syenite, and Squam Granite, all of which form a pluton covering 385 sq km. Intrudes Late Proterozoic greenschist, diorite, and gabbro that earlier workers assigned to Marlboro Formation, Salem Gabbro-Diorite, or Middlesex Fells Volcanic Complex. Dennen (1975) considered masses of diorite and gabbro within and adjacent to Cape Ann Complex to be cogenetic with it and equivalent in age to Nahant Gabbro and gabbro at Salem Neck. Authors recommend that usage of term Salem Gabbro-Diorite be restricted to these masses of diorite and gabbro in and around Cape Ann pluton that are younger than Dedham Granite and cogenetic with Cape Ann Complex. Gabbro at Salem Neck is probably representative. Radiometric ages straddle Late Ordovician-Early Silurian boundary. Age is based on Rb-Sr whole rock isochron of 426 +/-6 Ma (Zartman and Marvin, 1971) and U-Pb zircon date of 450 +/-25 Ma (Zartman, 1977) (Wones and Goldsmith, 1991).

Part of Milford-Dedham Zone (Tertiary and Older Rocks) Secondary unit description per MA007.


References for regional geology:

Data provided by Macrostrat.org

Garrity, C.P., and Soller, D.R.,. Database of the Geologic Map of North America: adapted from the map by J.C. Reed, Jr. and others (2005). U.S. Geological Survey Data Series 424 .

USGS compilers. State geologic map data. State Maps.

Geological Survey of Canada. Generalized geological map of the world and linked databases. doi:10.4095/195142. Open File 2915d.


Localities in this Region


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

Cooke, Josiah P., Jr. (1866): On Danalite, a new Mineral Species from the Granite of Rockport, Massachusetts, American Journal of Science and Arts: 47: 73-78.

Cooke, Josiah P., Jr. (1867): On Cryophyllite, American Journal of Science and Arts: 48: 217.

Knowlton, W. J. (1867). On a new mineral from Rockport, Massachusetts [Cyrtolite], American Journal of Science and Arts, 2nd Series, 44: 224-226.

Shaler, N. S. (1888): The Geology of Cape Ann, Massachusetts, USGS Ninth Annual Report.

Merrill, George P. (1889): The Collection of Building and Ornamental Stones in the U.S. National Museum, p. 287.

Warren, Charles H. (1903) Anthophyllite [= Ferro-anthophyllite] and Fayalite from Rockport, Massachusetts, American Journal of Science, 4th series: 16: 337.

Sears, John Henry (1905): The Physical Geography, Geology, Mineralogy and Paleontology of Essex County.

McKinstry, H. E. (1921): The Minerals of Rockport, Massachusetts, American Mineralogist: 6: 56-60.

Palache, Charles (1950): Fayalite at Rockport, Massachusetts, American Mineralogist: 35: 877-881.

Dunn, P. (1976): Genthelvite and the helvine group, Mineralogical Magazine: 40: 627-636.

Lyons, Paul (1976): The Chemistry of Riebeckites of Massachusetts, Mineralogical Magazine: 4: 473-479.

Bozhilov, K. N. & B. W. Evans (2001): Ferroanthophyllite in Rockport grunerite: A transmission electron microscopy study, American Mineralogist: 86(10): 1252-1260.

Mineral and/or Locality  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2016, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: December 3, 2016 04:41:15 Page generated: November 9, 2016 14:49:33
Go to top of page