Cold Spring, Town of Philipstown, Putnam County, New York, USAi

Regional Level Types
Cold Spring	Village
Town of Philipstown	Town
Putnam County	County
New York	State
USA	Country

Cold Spring is located about 2 3/4 miles south of the northern edge of the Hudson Highlands, a sub-region of the Reading Prong. The Reading Prong is an elongate area, stretching from westernmost Connecticut to near Reading, Pennsylvania, underlain by mid-Proterozoic igneous rocks and granulite facies gneisses along with minor post orogenic granites and pegmatites.

The rocks of the Reading Prong were folded and subjected to both ductile and brittle fracturing during the Paleozoic. One prominent feature is the complex imbricate thrust faulting which in some areas placed Proterozoic metamorphic rocks on Paleozoic sediments. In the Cold Spring area, such a “shuffling of the deck” did not occur.

A great deal of geologic work has been done in the Reading Prong, most of it west of the Hudson River, especially in New Jersey. There is surprisingly little modern geologic work published for the Cold Spring, NY area, the West Point 7.5' quadrangle, or for the eastern Hudson Highlands generally. A look at the references in an extensive and recently published paper on the Tilly Foster Iron Mine (Nightingale and Wilson, 2016), located about 20 miles east of Cold Spring, is instructive on this point.

By far, the most interesting mineral species reported from the Cold Spring area is an axinite-group species. It appears that axinite was found in the Cold Spring area only once and, although a few specimens are preserved in museum collections, the circumstances of its discovery are largely unknown. The locality was mentioned in mineralogy books at least as early as 1861 (Bristow, 1861). Valiant (1900), gives an extensive discussion of the collection, at Rutgers University, of Lewis Beck. Beck had written a treatise on the mineralogy of New York in 1842 with no mention of axinite. However, Valiant (1900)notes that his collection included 2 specimens of axinite from Cold Spring, apparently obtained before his death in 1853. It is interesting to note that in the interim, the Hudson River Railroad was built through the area in the late 1840s. A travelogue, published in 1851, notes that "The (rail)road passes directly through the village of Cold Spring, where two formidable rock cuts were encountered."

A specimen of axinite from Cold Spring, in the NY State Museum, does not include any of the country rock but does contain some tourmaline and actinolite. Two other small specimens in the collection of the Peabody Museum at Yale are accompanied by records indicating that they were sent to Prof. George Brush by Silas R. Horton. Horton lived near Goshen, NY, about 25 miles west of Cold Spring. He was a very active field collector for many years, focused on Orange County, NY, his home area. Horton supplied many specimens of various minerals to Brush over many years in the mid 19th century and also to others including Beck. It is not known if Horton was the original collector, but he's certainly a prime candidate.

The northwestern margin of the Reading Prong highlands is the site of eight documented alpine cleft type mineral occurrences that contain axinite-group minerals. This grouping does not include the axinite-Mn found in the Franklin, NJ zinc orebody. Nor does it include the axinite-Fe at the Tilly Foster iron mine near Brewster, NY, whose age and mode of occurrence have not been investigated in any detail. All the better documented axinite localities along the northwest margin of the Reading Prong highlands are found in a narrow, well-defined set of circumstances. All are alpine cleft type veins in calcium – rich gneiss (amphibolite, skarn) or in pegmatite closely associated with marble. The axinite-group mineral bearing veins are situated near, but not within, major faults and are in proximity to Paleozoic rocks. In the Cold Spring area, calcium-rich lithologies appear to underlie significant areas. The mineral assemblages given in Mindat for all three sub localities listed under “Cold Spring” suggest a calcic environment. The metamorphic rocks of the area are cut by a number of larger faults, and minor brittle fracturing is common in some intervening areas. The occurrence of epidote, a mineral commonly associated with axinite at other localities in the region, at the Mount Taurus Quarry is given, in Mindat, as “druses of microcrystals in calcite-filled vugs”. This is very reminiscent of axinite-bearing veins elsewhere in the region. Similar vuggy, epidote-bearing veins are not rare in parts of the Cold Spring area (Hershel Friedman, personal communication, 2017). Proximity to Paleozoic sedimentary rocks at the time of mineralization is unknown, but separation was probably not that great.

The criteria that indicate favorable conditions for the occurrence of axinite in alpine cleft type veins are all present in parts of the Cold Spring, NY area. The axinite found near Cold Spring in the mid-nineteenth century likely represents the 9th such occurrence in the region. That it is represented by a single find is typical, since most of the occurrences in the region are very small.

Fossils

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Other Databases

Wikipedia:	https://en.wikipedia.org/wiki/Cold_Spring,_New_York
Wikidata ID:	Q1016615
GeoNames ID:	5113196

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