A town on the east side of the Connecticut River, just southeast of Hartford. The bedrock geology consists of continental clastic sedimentary rocks (Portland Formation) within the Mesozoic Hartford Basin under the westernmost part of town, though these are mostly covered by Pleistocene deposits, and, in the Eastern Highlands, metamorphic rocks of the Bronson Hill terrane under the eastern part of the town. Most of the Bronson Hill bedrock is the Ordovician Glastonbury meta-plutonic gneiss, flanked on the east and west by Collins Hill formation, and unconformably overlain by the Silurian-Devonian meta-sedimentary Fitch, Clough, and Littleton formations in a north-northeast trending syncline near the eastern edge of town. Numerous pegmatites intrude these units, most notably just south of the village of South Glastonbury near the Portland line. This swarm is the northern part of the Middletown Pegmatite District.
The diversity of mineralogy found within the town is dominated by the pegmatites, which include both common and mariolitic, lithium-rich types. Rock forming and accessory metamorphic minerals are found in the meta-plutons and meta-sediments, and low temperature hydrothermal minerals are found in later faults and fractures.
Coordinates are for the town center green.
Mineral ListMineral list contains entries from the region specified including sub-localities
103 entries listed. 46 valid minerals.
Localities in this Region
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