Marie Duclos was born in France and at some unknown date married Joseph Fretageot. She met William Maclure in Paris in 1819, not long after he had become President of the Academy of Natural Sciences of Philadelphia. Madame Fretageot moved to Philadelphia in 1821, where she established a school and, like Maclure, became interested in Robert Owen's principles for social reform.
In 1826 both Maclure and Madame Fretageot moved to New Harmony to join in Robert Owen's experimental community. For reasons of health, Maclure resided there only a short time, but Madame Fretageot remained and managed his continuing financial support of science and education in New Harmony÷against great odds. In February, 1833 she joined Maclure in Mexico City, and that August, she died there.
Josephine Mirabella Elliott, Partnership for Posterity: The Correspondence of William Maclure and Marie Duclos Fretageot, 1820-1833, Indiana Historical Society, Indianapolis, 1994.