Enegren Mica Mine (Power Mica Mine), East Hampton, Middlesex Co., Connecticut, USA

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Three cuts and shallow mines in apparently four small common pegmatites, though the core of the pegmatite in the no. 1 cut shows some cleavelandite. From Cameron et al (1954):

"...David E. Enegren, of Middle Haddam, owner of the property. A gravel road leads westward 0.15 mile from Mr. Enegren’s house to the mine.

The mine was worked for a short time prior to 1940. It was reopened in July 1942 by the Power Mica Co., Hopkinton, Mass., who operated it intermittently until November 1944. Peter Armando of Glastonbury operated the mine from November 20 to December 20, 1944. Rock moved during 1944 contained slightly more than 2 percent mine-run mica.

Workings consist of opencuts and underground workings (fig. 131). The no. 1 cut has a maximum length of 53 feet, a width of 30 feet and a depth of 75 feet. It is connected with two small stopes and with an inclined shaft 25 feet deep. Cut no. 2 is 21 feet long, 12 feet wide, 22 feet deep; cut no. 3 is 25 feet long, 27 feet wide, 15 feet deep. All the cuts were flooded in February 1945. It is believed that none were backfilled...

The no. 1 cut has been the chief source of book mica, as it contains a higher percentage of mica than the other pegmatites. The pegmatite mined in the cut consists of a border zone and a core. The border zone, 4 inches to 1 foot thick, lies adjacent to the wall. It is fine-grained and consists of gray quartz and colorless to pale ruby muscovite. Subordinate minerals are albite (An2) and accessory red garnet [probably almandine], black tourmaline [schorl] and pyrite.

The core of the pegmatite is medium- to coarse-grained (grain size ½ inch to 4 inches). It consists of salmon-pink perthite [microcline] and gray quartz with subordinate amounts of albite (An2), in part cleavelandite, and rum-colored muscovite. Accessory minerals are black tourmaline, red garnet, green apatite [fluorapatite], and pale green beryl. Beryl forms rare euhedral prisms 1½ inches long, embedded in quartz and albite...

The no. 2 cut is situated in a tabular pegmatite that is probably about 120 feet long and 5 to 6 feet thick. It strikes N. 15° W. and dips 70° E. The no. 3 pit is in three narrow pegmatites, which strike N. 15-20° W. and dip 60-70° N. The two easternmost pegmatites end along strike within the workings; the southward termination of one and the northward termination of the other are exposed. The westernmost pegmatite is the one worked in the no. 2 cut.

The pegmatites in the no. 2 and no. 3 cuts are similar in composition and texture, and each has a fine-grained border zone, 1 to 6 inches thick, consisting of quartz and muscovite with subordinate albite. The cores of the pegmatites consist of salmon-pink perthite and gray quartz, with subordinate albite and accessory muscovite, black tourmaline, red garnet and green apatite. Perthite occurs commonly in anhedral crystals 6 inches to 1 foot in length, and less commonly in subhedral crystals. Muscovite, in pale rum books, ½ to 8 inches in diameter, is irregularly scattered throughout the pegmatite. Most books are of very poor quality and contain structural defects, especially ruling.

Like the main productive pegmatite, these are disseminated mica deposits. Production records show that they were too lean in book mica to repay mining, and the unexposed portions are probably no better."

Mineral List

Albite var: Cleavelandite Almandine

Beryl Fluorapatite Microcline

Muscovite Pyrite Quartz

Schorl

10 entries listed. 9 valid minerals.

References

External Links