Platinum is a heavy, silvery metal commonly found associated with other allied metals iridium, osmium, palladium, rhodium, and ruthenium. The name is derived from the Spanish, “platina” meaning little silver as they called it when they first discovered it in Columbia in the 1500’s. The catalytic properties of all these metals are outstanding, and one extensive use is automobile catalytic converters. Another use of platinum is is making fine jewelry due to its lack of tarnishing characteristics. Another property is its heat resistance of platinum, and platinum alloys are extensively used for forming crucibles for the growth of single crystals, especially oxides. The other characteristics of platinum group metals (PGM) are very useful to man: they include resistance to chemicals, excellent high temperature characteristics, and stable electrical properties. All of these properties have been exploited industrially by man.
PGM’s are associated with mafic and ultramafic igneous rocks, and their metamorphosed equivalents commonly called ophiolites or serpentinites. These kinds of rocks are relatively common in the Appalachian Mountains, and in many places PGM’s are found associated with them. As igneous rocks they are commonly emplaced in the country rock as lamproites having PGM’s associated with them too. A third type of rock having PGM’s associated with them are massive deposits of gabbros.
In eastern Connecticut the so-called Preston Gabbro the Foxwoods Resort Casino is located in this formation. Several years ago Richard Hayward who was at that time the head of the Mashantucket Pequots told me in a personal conversation that when they were drilling the wells for Foxwood’s they were bringing up platinum in the drill cuttings.
At the Wesleyan College Museum in Middletown, Connecticut there is on display a large nugget of PGM discovered many years ago at the falls of the Quinebaug River in Norwich, Connecticut. The nugget is about the size of the end of your little finger, and probably weighs over an ounce.
Ophiolites are found all along the eastern limb of the Appalachians having been laid down during the Late Ordovician during the Taconic Orogeny. These are translated to be pieces of oceanic crust that were caught up in the mountain building process. Another group of ophiolites can be found in eastern Maine associated with the Acadian Orogeny that occurred during the Devonian Era.
It was reported that gold panners panning for gold in the eastern Green Mountains in Vermont kept throwing away a heavy silvery metal that kept collecting in their gold pans. Finally someone had this metal analyzed and discovered that it was platinum.
Anywhere in New England where there are deposits of mafic, ultramafic igneous rocks, or ophiolites it might be that you will also find PGM’s. You can find out about the emplacement of any of these rocks by asking your state geological survey about them. Two other sources of information are local rock shops who usually have local guides available, or local historical societies who usually have historic records available explaining what minerals were found in their particular town.