Corporate Drive, Long Hill, Trumbull, Fairfield County, Connecticut, USAi

Regional Level Types
Corporate Drive	Industrial Site
Long Hill	Hill
Trumbull	Town
Fairfield County	County
Connecticut	State
USA	Country

A rock cut adjacent to a private corporate facility on Corporate Drive. Blasting took place in 2011-2012 exposing a contact between rusty The Straits Schist above its so-called basal member (marble and amphibolite with accessory scheelite), which is equivalent to the Russell Mountain Formation in Massachusetts.

At least 11 high-temperature hydrothermal veins to approx. 0.75 m wide are exposed in the rock cut. They are steeply dipping and planar, without brittle fracturing or brecciation and cross-cut amphibolite, marble and schist. As is typical in the area, the adjacent amphibolite shows purple-brown metasomatic alteration to fine-grained marialite and phlogopite. The veins contain mostly fluorite (variety chlorophane) and quartz core zones with distinct marginal zones consisting of euhedral albite crystals, muscovite (not margarite, based on Raman spectroscopy), marialite (based on Raman spectroscopy), and phlogopite where the contacting amphibolite has been metasomatized. Raman spectroscopy shows these crystals are albite variety oligoclase, the typical composition for metamorphic albite in Connecticut. These crystals reach up to 4cm and are white with distinctive steep terminations as well as occasional pyrite lamellae. Surprisingly, topaz is generally lacking, unlike other similar veins in the area, including those exposed uphill and to the south across the street, see http://www.mindat.org/loc-217040.html, where it is abundant. The chlorophane, present in large cleavable masses, is colorless to smoky and unless protected from daylight immediately upon its exposure loses its SW UV fluorescence.

As found in the surrounding area, the amphibolite (which hosts mostly sub-cm, scattered grains of scheelite) has been altered, with abundant clinozoisite, marialite, clinoclore, and quartz. It also contains zones and anhedral crystals of green albite variety oligoclase. Hydrothermal activity deposited pyrite and pyrrhotite in this unit, the marble, and the fluorite-quartz veins. Although the scheelite is predominantly restricted to the amphibolite, tiny grains were detected by fluorescence along and proximal to the high temperature veins in the marble as well, apparently mobilized by the associated hydrothermal activity.

Low-temperature hydrothermal activity deposited lamellae of pyrite, red-orange fluorescing calcite, and purple fluorite in thin fractures in all of these units.

NOTE: This outcrop is private property and is now off-limits to collecting, stop in the parking lot to view it, but please leave it alone.

Please respect the primary areas of collecting interest at this locality. I am avidly researching the genesis of fluorite veins here. I require assistance in performing spatially resolved XRF analysis of plagioclase feldspars as well as delta O analysis of the veins and country rock. If anyone can help with this project, please message me (Jeremy A. Zolan.)

Other Regions, Features and Areas containing this locality

References