A translucent, spotted leek-green, green quartz, which loses its polish
on exposure to the air, is known as prase.
This stone is found principally in the iron mines of Brietenbaum,
Saxony, and also in Brittany, the Tyrol, Scotland, Salzburg, Finland,
and the United States.
Prase is sometimes known commercially as “mother of emerald,” and a
greenish crystalline quartz is also often called prase.