Log InRegister
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 Articles
Minerals by PropertiesMinerals by ChemistryAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
Mining CompaniesStatisticsThe ElementsUsersBooks & MagazinesMineral MuseumsMineral Shows & EventsThe Mindat DirectoryDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery

Markham mica Quarry, Hog Hill, East Hampton (Chatham), Middlesex Co., Connecticut, USA

This page is currently not sponsored. Click here to sponsor this page.
From Cameron et al (1954):

The Markham mica mine lies in the town of East Hampton, 1.5 miles S. 45° E. of the village of Cobalt. From Cobalt travel 0.8 mile east on U. S. Route 6 to the Colchester road; proceed east on this road for 0.4 mile; turn southward on a gravel road that leads 1.3 miles to the deposit. The workings lie in rolling woodlands, about 100 feet east of the gravel road.

The property is owned by Mrs. Grace Markham and her two sons. Mining was started by Peter Armando, of Glastonbury, and Romano Milanese, of Higganum, who leased the property and operated it intermittently from November 1943 to April 1944. In March 1944, when examined by V. E. Shainin, the working was an open pit 25 feet long, 12 feet wide, and 14 feet in average depth. The long axis of the cut had a trend of N. 65° W.

The opencut is in an irregular pegmatite that strikes N. 30° E. and dips 65° NW. The pegmatite is exposed only in the cut. It is about 20 feet thick, and is concordant with the foliation of the enclosing medium-grained quartz-mica schist (Bolton schist). Two schist screens lie 4 to 6 feet below the ground surface. The screens are roughly parallel to the walls of the pegmatite, extend across the width of the opencut, and each is about 2 feet thick.

The pegmatite is composed chiefly of quartz and [microcline] perthite; it possesses a border zone and core. The border zone is 1 to 6 inches thick and consists of fine-grained quartz, plagioclase [albite], and muscovite. Essential minerals in the core are medium- to coarse-grained quartz, [microcline] perthite and muscovite. Garnet [most likely almandine], tourmaline [schorl], biotite [annite] and apatite [fluorapatite] are accessories.

The pegmatite is a disseminated mica deposit. Hard, pale green and pale ruby mica occurs in scattered books that range from ½ to 4 inches in diameter and average 2 to 3 inches in diameter. The books are heavily intergrown with tourmaline, feldspar, and quartz, and probably contain less than 1 percent of sheet mica. Common defects are “A” structure, reeving, limonite-staining and cross-fracturing. Subhedral inclusions of flattened tourmaline are common; ruling and wedging are present, but are uncommon.

The workings were abandoned because the percentage of mica in rock moved was low and the content of sheet mica in mine-run mica was low. The exposed part of the pegmatite is unpromising as a source of sheet mica, and it is unlikely that a better deposit exists at depth.

Mineral List

9 entries listed. 8 valid minerals.

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.


Cameron, Eugene N., Larrabee David M., McNair, Andrew H., Page, James T., Stewart, Glenn W., and Shainin, Vincent E. (1954): Pegmatite Investigations 1942-45 New England; USGS Professional Paper 255.

External Links

Mineral and/or Locality  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization. Public Relations by Blytheweigh.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2019, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: June 16, 2019 19:58:29 Page generated: January 14, 2015 09:41:19
Go to top of page