"Prase" is a technical term used in geology to describe a type of green quartz. However, there are other words that can be used as synonyms to describe a green gemstone. For example, "emerald" refers to a brilliant green variety of beryl, while "jade" refers to a green mineral that's often used for carvings and jewelry. "Peridot" is another green gemstone, which is a type of olivine mineral. "Malachite" is a green stone that's often used for decorative objects and jewelry. Finally, "kryptonite" is a fictional green mineral that's famously known for being the weakness of Superman.