James Kelly farm, Pyrites, St. Lawrence County, New York, USAi

Regional Level Types
James Kelly farm	Farm
Pyrites	- not defined -
St. Lawrence County	County
New York	State
USA	Country

History
The James Kelly Farm (Pyrites Mica Mine) is a former mica operation located near the town of Pyrites, New York. The first recorded activity at this locality was in 1901 when a local geologist formed a contract with then landowner William Kelly for the recovery of mica (phlogopite) from the property. It's unclear how much mining activity occurred throughout the sporadic leasing of the property over the next several decades, although two small pits are still extant at the property. The site was visited periodically by collectors, although most collecting took place in recent years before the property was sold in c. 2019 by the Kelly Family. It is unclear if collecting will be permitted by the new property owner (C. Emproto, 2022).

Geology
The lithology hosting mica mineralization at the James Kelly Farm consists of veins of crustally-derived carbonatite that have intruded a pelitic gneiss near the contact of the gneiss and local marble units adjacent to leucogranitic intrusions. The carbonatite most likely formed at c. 1150 Ma during igneous activity associated with post-orogenic extension during the Shawinigan phase of the Grenville orogenic cycle. Magma and magmatic fluids produced during this stage instigated the partial melting of local marble units leading to remobilization of these components (mixed with magmatic fluids)as crustally-derived carbonatites (Emproto, 2020).

The carbonatite consists primarily of orange calcite with fluorapatite and abundant (c. 5%) pyrite. The abundance of pyrite is very unusual for a Grenville crustal carbonatite. Phlogopite, meionite, titanite, and diopside are mostly found at the coarse silicate margins where the carbonatite was in contact with the host gneiss (Emproto, 2020). These margins are primarily coarse meionite. Druzy quartz and iron oxides appear to have formed much later than carbonatite mineralization from the infiltration of silica-rich fluids and oxidation of primary pyrite, respectively, and can encrust fluorapatite and other minerals. Phlogopite may also be partly or wholly altered to clinochlore, which can result in partly deformed pseudomorphs (Chamberlain et al., 2018). It is unclear when these later mineralizing events occurred. Dravite has also been found in one of the exploration pits, but very little is known of this sub-occurrence; it may potentially be similar to the fluor-uvite and tremolite mineralization that occurs at the nearby Selleck Road/East Pits locality and is most likely not from the carbonatite mineralization that hosts fluorapatite and phlogopite. For more information about the minerals that occur at this site, see: Chamberlain et al. (2018).

Other Regions, Features and Areas containing this locality

References