Nephrite "hei-tiki" (neck pendant). These are believed to have their own "mana", are handed down as valuable heirlooms, and often given as gifts to seal important agreements. It has also been used for a range of tools such as adzes, as Māori had no metal tools before European contact. Commonly called "greenstone", jade jewellery in Māori designs is widely popular with tourists. Stone is often imported from Canada, China and Siberia, and Ngai Tahu runs a pounamu certification scheme to verify the authenticity of New Zealand stone. Nephrite Nephrite is a variety of the calcium, magnesium, and iron-rich amphibole minerals tremolite
Theory of forms to some of the problems that are made to puzzle the younger. The dialogue does present a very real difficulty with the Theory of Forms, which Plato most likely only viewed as problems for later thought. These criticisms were later emphasized by Aristotle in rejecting an independently existing world of Forms. It is worth noting that Aristotle was a pupil and then a junior colleague of Plato; it is entirely possible that the presentation of "Parmenides" "sets up" for Aristotle; that is, they agreed to disagree. One difficulty lies in the conceptualization of the "participation" of an object in a