One of the earliest known uses of the word "erin" to describe a color appears in the poetry of Jane Johnston Schoolcraft (1800–1842). In a poem titled To the Pine Trees, Schoolcraft reflects on her arrival back to North America after spending years in England she writes "Not all the trees of England bright, / Not Erin's lawns of green and light / are half so sweet to memory's eye, / As this dear type of northern sky." 
^ Maerz and Paul A Dictionary of Color New York:1930 McGraw-Hill Page 194; Color Sample of Erin Page 81 Plate 29 Color Sample F12; A deep tone of the color Erin is shown as lying half way between a deep tone of green and a deep tone of the color that is now called spring green, on the bottom row of color samples on the color plate, which represent the deeper tones of the colors between green and the color now called spring green.
^Parker, Robert (2007). The Sound the Stars Make Rushing Through the Sky: The Writings of Jane Johnston Schoolcraft. University of Pennsylvania Press. ISBN978-0812219692.