The History of the Several Towns, Manors, and Patents of the County of Westchester (1881 revised edition, Vol. I)
The return of a belt was understood as the rejection of an offer or of the terms accompanying the same. A string of 'Sea wan' was sometimes delivered by the orator in public council at the close of each proposition as ratifying the speaker's truth and sincerity. Strings of 'Wampum' were occasionally tied around the neck of a white dog, and the animal thus decorated was fastened to a pole and offered up as a sacrifice to 'Thalonghyawaagon,' the upholder of the skies. Long Island was called ' Seawan-Hacky,' the Island of Shells. Immense quantities of Seawan were manufactured there. In the extensive shell-banks left by the Indians, a whole shell is rarely found, nearly all having been more or less broken in the process of making 'wampom.' The French at one time made unsuccessful efforts to circulate a porcelain counterfeit. The Dutch manufactured great quantities from the genuine material -- their superior mechanical facilities giving them much advantage over the Indians. The Dutch valued three purple beads at one Stuyver (penny) -- double the price of the white beads.
"According to Loskiel, 'Wampum' or 'Wampom,' signifies in the language of the Iroquois a 'muscle.' 'These muscles,' he says, 'are chiefly found on the coast of Virginia and Maryland, and are valued according to their color, which is brown, violet, and white. The former are sometimes of so dark a shade that they pass for black, and are double the price of white. Having first sawed them into square pieces about a quarter of an inch in length and an eighth in thickness, they grind them round or oval upon a common grindstone. Then a hole being bored lengthways through each, large enough to admit a wire, whipcord, or thin thong, they are strung like beads and the string of 'wampom' is complete.