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Minerals
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
The term tenacity refers to a mineral’s toughness and its resistance to breaking or deformation. Those that break, bend, or deform easily have little tenacity. In contrast, strong unbreakable minerals have great tenacity. Figure 3.42 shows samples of the gemstone jade that have been shaped and polished to produce a figurine and a cabochon. Gemmy jade may be composed of either of two minerals: jadeite (a pyroxene) or nephrite (an amphibole). In either case, jade is one of the most tenacious natural materials known. It does not easily break or deform, even when under extreme stress. That is one of the reasons, besides beauty, that it is prized as a gemstone.
Inorganic Polymers
Published in Charles E. Carraher, Carraher's Polymer Chemistry, 2017
Jade, which has been valued in carving by eastern Asians for centuries, is generally one of two minerals—pyroxene or jadeite (NaAl(SiO3)2) and the amphibole nephrite (Ca2(Fe+2 and/or Mg+2)5 (Si4O11)2(OH)2). X-ray diffraction has shown the presence of triple chains in nephrite.
A review of the occurrence of and potential for jade in the New Guinea Mobile Belt
Published in Australian Journal of Earth Sciences, 2022
Gemmologists recognise two rock types encompassed by the term jade. Nephrite is a fine-grained rock consisting predominantly of tremolite–ferro-actinolite [Ca2(Mg,Fe)5Si8O22(OH)2] (Harlow et al., 2014). Nephrite is distinctive for its translucency along thin edges, high specific gravity and toughness. It breaks with a splintery fracture and has a glistening lustre. Its texture is characterised by randomly oriented bundles, tufts and sheaf-like groups of felted and twisted fibres. Minor to trace inclusions in nephrite include magnetite, chromite, diopside, grossular garnet, graphite, apatite, rutile, pyrite, talc and serpentine. Jade composed of the mineral jadeite is known as jadeite jade, jadeite rock, pyroxene jade or jadeitite (Harlow et al., 2014, Leaming, 1978). Jadeite jade is rare and is generally defined as consisting of ∼90 vol% pyroxene containing at least 90 mol% jadeite [jadeite = NaAlSi2O6] (Harlow et al., 2014; Leaming, 1978). The term pyroxene jade may be used when the composition of the pyroxene is in doubt (Harlow et al., 2014). Jadeite jade is a tough, hard, heavy, equigranular aggregate of prismatic pyroxene crystals. Its texture is characterised by granoblastic to feathery microstructures (Harlow et al., 2012, 2014). Chloromelanite is the name for a dark iron-rich pyroxene variety of jade rich in aegirine (NaFe3+Si2O6) and omphacite [(Na0.5Ca0.5)([Mg,Fe]0.5Al0.5)Si2O6 or Jd50(Di + Hd)50] or augite [(Ca,Mg,Fe)2Si2O6] (Harlow et al., 2014). References to chloromelanite are commonly found in New Guinea literature, and its use is retained in this paper.