By resolution of the Middletown Selectmen, “The inhabitants of Middletown for the encouragement of the designs of our much honored governor, Mr. John Winthrop, for the discovery of mines and minerals and for the setting up of such works as shall be needful for the improvement of them, do hereby grant unto our said much honored governor any profitable mines or minerals that he shall find or discover upon any common land with the bounds of our town and such woodland as may be convenient for the use of the same, to the value of 500 to 1,000 acres, as it may lie so that it be not nearer than two or three miles from the present dwelling houses of the Town, and as the Town shall judge to be lest prejudicial to themselves for their necessary firewood, provided the Town shall have free liberty of commonage, as far as our Town bounds go, until the improvers shall see good to impropriate the same with inclosures – provided further that said governor, and such as may be co-improvers with him, will set up the works to improve such mines and minerals as he shall find, within these 5 years and let us know whether he doth accepts of this our grant with two years; and so be it to him and his heirs and associates from the time of setting up such works, else at two or fives years, and to be in liberty of the Town to grant the same to any other. May 23, 1661.”
President Stiles of Yale College wrote, “1787, Jan.1, Mr. Erkenlen’s (developer of Cobalt mine) visited me, full of his Cobalt mine and China voyage. He some years ago bought the Governor’s Ring, as it is called, or a mountain in the N.W. corner of East Haddam (Middle Haddam), comprehending about 800 acres, or about a square mile area. Here he finds plenty of Cobalt, which he manufactures into smalt with which is made the beautiful blue on China ware, etc.” “Gov. Trumbull has often told me that this was the place to which Gov. Winthrop of N. London used to resort with his servant, and after spending three weeks in the woods of this mountain, in roasting ores and assaying metals and casting gold rings, he use to return home to New London with plenty of gold. Hence this is called the Gov. Winthrop ring to this day.
From correspondence of the governor with learned men in England, it is possible that some knowledge of this locality crossed the Atlantic in his time (Winthrop’s). Be this as it may, no considerable efforts appear to have been made to find gold or any other mineral in this hill, for about a century after this grant was made. But about 1762, Dr. John Sebastian Stepancey, a German, employed a number of men, and made a horizontal opening into the hill in search of hid treasures. He continued his exertions but a short time. About 1770 he renewed them, in connection with tow other Germans, John Knool and Gominus Erkelens; but at length it appears that he made over the management of the concern to his associates, reserving to himself only a portion of the profits, and there was an agreement that what metals and minerals were sent to Great Britain should be consigned to Knool’s friends, and those sent to Holland to Erkelens’.
Geologists and Professors from UCONN actually did some experimental mining in the late 1980s recovering a reasonable (maybe an ounce or two) of gold, but determined there was insufficient quanity to ever make mining a commercially viable enterprise.