Cheshire Traprock Quarry, Cheshire, New Haven County, Connecticut, USAi

Regional Level Types
Cheshire Traprock Quarry	Quarry
Cheshire	- not defined -
New Haven County	County
Connecticut	State
USA	Country

An old, long inactive traprock quarry in Peck Mountain on the West Rock diabase sill. Exact dates of activity are uncertain, but the quarry is not mentioned in literature older than Schairer (1931). It is active, though relatively small, on 1934 aerial photographs, the first available. Hiller (1971) calls it inactive.

Schooner (1961) calls this area "near Roaring Brook" or just "Roaring Brook", though the well-known waterfall exposure is 2.4 miles south of the quarry. He references Dana's System of Mineralogy 5th edition (1875), which correctly says Roaring Brook is 14 miles north of New Haven (the quarry is about 16.5). It is unlikely the quarry is that old and because Roaring Brook cuts a gorge through the sill, the falls on the brook is a separate locality.

The most productive area for minerals after quarrying was over is at the northwest end. Analcime and natrolite, typically together (with mostly calcite, prehnite and micro-albite crystals), were common there, but are very rare at other traprock quarries in Connecticut.

Some Cheshire specimens have been attributed to the traprock quarries in Woodbury and Southbury, Connecticut but natrolite and analcime are very rare there and the extrusive basalt matrix is very fine-grained or aphanitic. The West Rock sill diabase matrix, being intrusive, is relatively coarse-grained (1-2mm) and the dark augite and light plagioclase grains give it a salt and pepper appearance quite different from the Woodbury/Southbury matrix. Many Cheshire specimens also have a brown stain on the minerals that is unlike the other quarries. This is "limonite" that is easily cleaned off if desired.

Mindat Articles

Mineralogy of the Cheshire Traprock Quarry by Rowan Lytle

Other Regions, Features and Areas containing this locality

References