From Dr. L. Feuchtwanger A popular treatise on Gems, 1859

"This mineral is mentioned by Pliny; but it is not certain whether he meant the same substance that we do; more probably he alluded to the emerald; for the same mineral is at the present time called the emerald mother or matrix by jewelers.  Prase occurs massive and crystallized; it has a conchoidal fracture; its translucent on the edges; between vitreous and resinous in lustre; and of a garlic-green color, the cause of which is that actinolite is intermixed with silex"

"It is a translucent variety of quartz with somewhat greasy lustre and leak-green colour.  This last named character is due to the presence of innumerable minute fibres and needles of actinolite enclosed in the otherwise colourless and pure masses of quartz"

From Shipley's Dictionary of Gems and gemology, 4th edition, 1948

"Translucent light grayish yellow green quartz (1) cryptocrystalline (chalcedony) (Dana; Kraus); (2) crystalline and colored by inclusions of actinolite needles. (Smith; Schlossmacher)"

Somewhere along the line the designated color for this material was applied to the material chalcedony, just have to remember that the definition is slightly different between the material and still using the same variety name of Prase. The color of prase has also been applied to opal.