Unnamed magnetite occurrences, Higganum, Haddam, Middlesex Co., Connecticut, USA
|Latitude & Longitude (WGS84):||41° 29' 56'' North , 72° 33' 20'' West|
|Latitude & Longitude (decimal):||41.49889,-72.55583|
|Köppen climate type:||Cfa : Humid subtropical climate|
Numerous small, common, unzoned pegmatites with pink to reddish microcline cross-cut the Pond Meadow gneiss portion of what was called the Monson gneiss in the Higganum area. Natural and man-made exposures are too numerous to list. Some of these pegmatites contain magnetite crytals, but little else of interest. The crystals are octahedral to dodecahedral and deeply striated and can reach 2 to 3 cm.
Davis (1901) states that magnetite:
They have been noted by Foye (1922) in Higganum Creek west of Depot Road:
and by Williams (1945) on Ladderpole Hill between Higganum and Haddam center (an area similar to that described by Davis (1901)).
Map reference coordinates are for the Higganum Creek locality.
6 valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
|Middle Ordovician - Early Ordovician|
458.4 - 485.4 Ma
Age: Ordovician (458.4 - 485.4 Ma)
Stratigraphic Name: Monson Gneiss
Description: (May be equivalent to part of Waterford Group) - Interlayered light to dark, mostly medium to coarse-grained gneiss and amphibolite; gneiss composed of plagioclase, quartz, and biotite, with hornblende in some layers and microcline in others; traces of garnet, epidote, and magnetite.
Comments: Part of Eastern Uplands; Iapetus (Oceanic) Terrane - Bronson Hill Anticlinorium. Swanzey, Pauchaug, Monson, and Fourmile Gneisses represent metamorphosed intrusive igneous rocks and yield ages from 454 to 442+3/-2 Ma. Therefore, ages range from early Late through latest Ordovician. Authors suggest that they represent the plutonic root of a calc-alkaline magmatic arc at least 250 km long that was produced partly or entirely on a continental margin in the Late Ordovician. The overlying Ammonoosuc Volcanics and Partridge Formation, rather that resting unconformably on these plagioclase-rich plutonic gneiss, are now known to have had a magmatic history overlapping with them and are approximately the same age (Tucker and Robinson, 1990) per CT012.
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052.