## 4 The Example of the Green Stones
### The Nomenclature of the Green Stones  
One of the main issues related to Green Stones terminology is that the terms used to identify the materials belong to different disciplines, mixed together: gemology, cultural heritage, archaeology, mineralogy, and petrography. A brief discussion about the principal ones is reported below. \"Jade\" is a common trade term, and in the gemology field, it is applicable to identify objects made by only two gemological species: jadeite and nephrite [30; 84; 85]. This clarification is significant because, by this acceptation, it is possible to individuate the objects with the highest quality from several points of view within a huge group of materials. Particularly, nephrite gemological species identifies a rock originated from a solid solution of the amphibe group minerals actinolite and tremolite, composed of an interlocking mass of granular and acicular crystals without a preferred orientation. On the other hand, jadeite is a pyroxene mineral phase, and in gem-quality jadeite, columnar and/or granular crystals are aggregated. Moreover, in gem-quality jade, jadeite and nephrite are not the only minerals present: associations are common. For example, in jadeite, the presence of augite, diopside, aegirine, omphacite, and kosmochlor are expected, but to be defined as jadeite-jade, the dominant phase must remain the jadeite with the other phases in traces. In fact, only a high grade of purity of mineral aggregation is able to guarantee the hardness, toughness, and durability characteristics for which jade has become famous all over the world. The modern term jade reflects in its acceptation the antique etymology of the material. Indeed, these terms come from the old Spanish etymology: jade derives from \"piedra de la ijada\", a Spanish expression meaning \"stone of the loins\", from Latin \"_ilia_\" (\"hip\") [86,87]; and nephrite has its origin in the Spanish \"piedra de los r\(\hat{\text{n}}\)rones\" or \"stone of the kidneys\" [88]. It is interesting to note that the conquerors of the New World indicated by this second term the jade worn used by the indigenous people who believed in its healing properties [86]. Traces of the same therapeutical application are reported by [PERSON] [89] regarding the [PERSON] family of Florence during the Renaissance. Although there are not previous etymological clues on the western side of the world, and though the Romans did not appreciate the jades from what we know because they considered them to be unlucky, it is a fact that objects man-made in \"jade\" materials, such as ceremonial insignia and weapons, objects symbolizing the social status of their owners, and ritual and funery artifacts, have been found in a different part of the world since the Neolithic Age [85,90,91,92,93,94,95], attesting the high level of consideration for this material in ancient civilizations. On the other side of the world, in China, where a tradition of Green Stones use is well-documented since Neolithic times, the term \"Yu\"--literally \"the most beautiful stone\"--was used to describe not only jade but also other Green Stones, such as chalcedony and marble, that were carved into tools and ceremonial objects [87]. In the Chinese understanding, the corresponding term of jade was historically split into other two terms: Ying Yu (hard jade), also known as \"Fei Cui\", and Ruan Yu (soft jade), corresponding to the pyroxene varieties and other Green Stones, respectively. While the Laboratory Manual Harmonisation Committee (LMHC) and the World Jewellery Confederation (CIBJO) are very straight for jade definition [30,84], the same clarity is not always applied. Thus, when the term jade is used as synonymous with the Chinese \"Fei Cui\", or as a direct translation of it, several misunderstandings in the material identification can occur. Indeed, different eastern countries use the term Fei Cui to identify different materials. For example, in Japanese, the term Fei Cui is a synonym for jadeite-jade.