Bordonaro Quarry, Portland, Middlesex County, Connecticut, USAi

Regional Level Types
Bordonaro Quarry	Quarry
Portland	- not defined -
Middlesex County	County
Connecticut	State
USA	Country

Quarry and prospects in small granite pegmatite dike noted mostly for a relative abundance of beryl.

According to Cameron (1954) and Boos (1949), the property was owned in 1943 by Sam Bordonaro, of Portland. In 1929 Joseph Carini, worked one of the pegmatites on the property and recovered a few tons of feldspar, beryl and scrap mica. In 1935 Bordonaro mined feldspar and sold some run-of-the-mine mica to the Huse-Liberty Co., in Middletown, Conn.. The Bordonaro pegmatite strikes nearly N. - S. and dips west 25°-55°. The average dip is about 45°. The south half of the Bordonaro dike was mined in two sections. The first quarry was about 55 feet long and the second about 38 feet long. The two openings range from 1 foot to 10 feet in depth and for most of their length expose the pegmatite from wall to wall. A small prospect cut 30 feet south of the quarry exposes pegmatite.

The south section has a striking zonal structure. It consists of the following units, in order from the walls inward:

1. Border zone, plagioclase-quartz-perthite pegmatite, 1 to 3 inches thick. Composed of fine- to medium-grained quartz and albite plagioclase, with subordinate muscovite and microcline perthite, and accessory garnet and unevenly distributed beryl. The beryl crystals are ½ to 1½ inches in diameter and as much as 3 inches long.
2. Perthite-quartz zone, 3 inches to 1 foot thick. Composed of coarse perthite and quartz, with subordinate muscovite and albite plagioclase. The microcline perthite crystals are euhedral against the quartz and also against quartz of the core described below. The zone is absent along part of the footwall.
3. Quartz core, 6 inches to 1½ feet thick. Consists of coarse, massive quartz.

The north section of the dike consists of the following zones:

1. Border zone, ½ inch to 2 inches thick, similar to the border zone of the south section. The zone is absent at a few places along the hanging wall.
2. Wall zone, plagioclase-quartz-perthite pegmatite, 1 to 8 inches thick. Composed of quartz and albite plagioclase, with subordinate microcline perthite and muscovite and accessory beryl, tourmaline, and garnet. The zone is less than 4 inches thick in most places and is discontinuous. The mica books are ½ inch to 6 inches broad, and ¼ inch to 2 inches thick. The mica is green, clear, and hard, but most of it is ruled, reeved, cross-fractured, and tangled. Inclusions of albite, quartz, tourmaline, and garnet are present in some books. Few books would yield even small sheet mica.
3. Perthite-quartz zone, 6 inches to 5 feet thick. This zone varies markedly from place to place in mineral proportions, but in general consists of quartz and coarse microcline perthite, with subordinate medium-grained albite plagioclase and muscovite, and accessory beryl and garnet. Perthite forms anhedral to subhedral crystals a few inches to 3 feet in diameter. Some of the crystals are intergrown with quartz. Light green to blue-green subhedral beryl crystals as much as 6 inches long and 2.5 inches in diameter are scattered unevenly through the zone. Some of the crystals seem to be pure and some are intergrown with or include quartz and feldspars or are veined by quartz and albite.

The other pegmatites exposed on the property are medium- to coarse-grained and consist essentially of quartz, albite plagioclase, microcline perthite, and muscovite in various proportions. Apart from thin border zones, they appear unzoned.

Other Regions, Features and Areas containing this locality

References