White Rock Mining District, Middletown, Middlesex County, Connecticut, USAi

Regional Level Types
White Rock Mining District	Mining District
Middletown	City
Middlesex County	County
Connecticut	State
USA	Country

A roughly 1.6 km square (1 mile square) sub-district of the greater Middletown Pegmatite District of Connecticut. This area is named for the prominent, white, once treeless pegmatite ridges visible in the highlands to the east of Middletown center. It is situated between the Hartford Mesozoic Basin to the west, the Maromas Granite Gneiss to the east, the Connecticut River to the north, and reservoir and state forest land to the south.

The first publications of minerals found here are from Porter (1825), who noted molybdenite on his map, and Silliman (1826) describing colored tourmaline (red and green in parallel groups), beryl (light green 8-9 inches long and 5-6 inches across), and lepidolite in a pegmatite about 2.5 miles southeast of Middletown found by Stephen Williams in 1825.

Quarrying took place on 5 major north to northwest-trending pegmatite dikes or dike complexes, a large northeast-trending dike, and several smaller dikes. The area was intermittently active from about 1907 to 1959, then was continuously worked until 1993, producing 18 quarries with all the major quarries since flooded, filled, and/or built over.

With foresight Bastin (1910) briefly states:

"The White Rocks region is in general one of the most promising known to the writer for quarrying the best grades of feldspar...The situation is also favorable for cheap quarrying and shipment."

However, the area does not have good muscovite and so for decades could not compete with the quarries that received federal subsidies for this mineral. Most of the quarrying was done by The Feldspar Corp. after they took over the property in 1959 and leased additional land to the east. Unlike earlier pegmatite quarrying in Connecticut, by this time the feldspar was not sorted by laborious hand cobbing, but was crushed and sorted by chemical floatation. This allowed all of the pegmatite to be quarried and used, rather than just the zone of subhedral to euhedral microclines that grew against the quartz-rich core of internally zoned pegmatites. Quartz and ground mica were also produced. Consequently, as other quarries shut down following the end of mica and beryl subsidies that had made them economical, the White Rock district took off as the major pegmatite mining area of the state, profitably using mostly the large but poorly zoned pegmatites characteristic of the area.

Morgan (1968) reports that The Feldspar Corporation's floatation plant had a capacity of 200 tons of feldspar per 24 hours. The raw material consisted of 58% feldspars (combined albite and microcline), 33% quartz, 7% mica, 2% heavy minerals. From this raw material, the floatation process recovered 48% feldspars, 25% quartz, and 3% mica. The remaining 24% was waste, which was very fine powder used as backfill in some of the quarries. Because of this efficiency, pegmatite was also trucked to the mill from other quarries such as the Gotta-Wannerstrom and Hale in Portland, Arnold in Haddam, Selden in East Hampton, and Dripps Road in Middletown.

This page summarizes all the minerals found in the pegmatites and host metamorphic rocks (Middletown and Collins Hill Formations) and the coordinates are for the approximate center of quarrying activity. Major sub-localities consist of the Riverside Quarry and White Rocks Quarry, situated on the so-called "Eastern Dike" of Watts and Rice & Foye; unnamed quarries on northeast trending dikes to the immediate south and east; and the large, 1000-meter-long quarry in the northeast-trending pegmatite in the extreme southeastern part of the district. Other quarries in the center of the district are poorly documented and apparently did not produce minerals besides the typical albite, microcline, quartz with accessory muscovite, beryl, almandine, and fluorapatite.

Schooner (1958 and 1961) refers to the upper and lower White Rocks Quarries, these are actually the Riverside and Consolidated Quarries, respectively, both on the "Eastern Dike" of Watts and Rice & Foye. His directions to the Riverside Quarry is too far east because it was based on the map in Cameron et al (1958), which has it in the wrong place. Schooner's directions are to additional Consolidated Corp. quarries. Januzzi (1976) contains only a list of minerals that was taken directly from Schooner (1958). The pegmatite minerals in this list are attributable to specific quarries, so the references are used on this page for host rock minerals, which are best exposed on River Road north of the quarries.

Because most of the quarries in this large area do not have names, they were referred to by collectors generally as the White Rocks Quarries, leading to confusion or lack of documentation of the exact origin of specific minerals or specimens. However, generally the mineralogy and texture of the pegmatites varies systematically across the district. The pegmatite in the Eastern Dike has the most complex texture, with well-defined internal zones including cleavelandite and quartz rich cores zones, and lithium and rare-element-rich chemistry that yielded many elbaite, lepidolite, beryl, microlite, columbite-(Fe) and uranium mineral specimens. To the immediate east and south, the dikes are still zoned but without the cleavelandite and have simpler chemistry, producing mainly only beryl, schorl, fluorapatite, and garnet as major accessory minerals. The large northeast-trending pegmatite at the extreme SE part of the area has the simplest texture with no zoning and the least abundant accessory mineralogy. However, it is crossed by quartz veins that include pyrite and at its NE end produced the best molybdenite crystals in Connecticut.

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References