| 释义 |
pyroxene Min.|ˈpaɪərɒksiːn|
[f. Gr. πῦρ, πυρο- fire + ξένος stranger: so named by Haüy 1796, because he thought it ‘a stranger in the domain of fire’ or alien to igneous rocks.]
A species including a large variety of minerals, all bisilicates of lime with one or more of various other bases, most usually magnesia and iron oxide, but also manganese, potash, soda, and zinc, or two or more of these. In mod. use, any of a group of silicates characterized by the presence of single chains of SiO4 tetrahedra and prismatic cleavages at nearly 90 degrees, the general formula of which is approximately XY(SiO3)2.
Often identified with augite, q.v.; but, according to Dana, pyroxene ‘is properly the name of the species, while augite is only entitled to be used for one of its varieties’.
1800Philos. Mag. VII. 254 He [Vauquelin] has analysed the pyroxene of ætna. 1811Pinkerton Petral. II. 475 Few fragments of augite or pyroxene. 1833Lyell Princ. Geol. III. Gloss. 63 The modern Lavas of Vesuvius are characterised by a large proportion of augite (or pyroxene). 1862[see pyroxenite]. 1875Dawson Dawn of Life ii. 28 Pyroxene rock or pyrallolite. Ibid. v. 108 White pyroxene, an anhydrous silicate of lime and magnesia. 1888J. P. Iddings tr. Rosenbusch's Microsc. Physiogr. Rock-Making Minerals 202 The orthorhombic pyroxenes become transparent in various colors, according to the position of the section and to the iron percentage. 1906J. P. Iddings Rock Minerals ii. 286 (heading) Pyroxene group. Ibid., The triclinic pyroxenes are less closely related to the other forms, and are less frequently met with as rock-making minerals. 1959Dana's Man. Mineral. (ed. 17) 434 The pyroxenes crystallize at higher temperatures than their amphibole analogues and hence are generally formed earlier in a cooling igneous magma. 1966W. A. Deer et al. Introd. Rock-Forming Minerals ii. 99 The pyroxene group includes both orthorhombic and monoclinic minerals. The orthorhombic sub-group consists essentially of the compositional series MgSiO3FeSiO3 while the monoclinic sub-group includes members having a wide range of chemical composition. Ibid., The general formula of the pyroxene group may be expressed X1-pY1+pZ2O6 where X = Ca,Na; Y = Mg,Fe+2,Mn,Li,Ni,Al,Fe+3,Cr,Ti; Z = Si,Al. 1975D. Shelley Man. Optical Mineral. vii. 143 Most pyroxenes form rather stumpy prismatic crystals, though occasionally, as in the case of aegirine, the crystals are more elongate. 1978Sci. Amer. Apr. 125/2 Peridotite..is composed mainly of olivine and another silicate mineral, pyroxene.
Hence pyroxenic |-ˈɛnɪk| a., pertaining to, having the character of, consisting of, or containing pyroxene; pyroxenite |-ˈɒksɛnaɪt|, also -yte [see -ite1 2 b], a metamorphic rock consisting chiefly of pyroxene; pyroxeˈnitic a., of or pertaining to pyroxenite.
1828Webster, *Pyroxenic, pertaining to pyroxene, or partaking of its qualities. 1830Lyell Princ. Geol. I. 328 Violent explosions, like those which, in 1822, launched from Vesuvius a mass of pyroxenic lava, of many tons weight, to the distance of three miles. 1893Nation (N.Y.) 27 July 71/1 Bunsen's Theory of pyroxenic and trachytic magmas forms the starting-point for all theories for the differentiation of magmas.
1862Dana Man. Geol. §8. 78 *Pyroxenite... Coarse or fine granular pyroxene rock, consisting of granular pyroxene of a grayish green or brown color. 1868― Min. (ed. 5) 220 Pyroxenyte is a metamorphic rock consisting mainly of compact pyroxene of the Sahlite section.
1933R. A. Daly Igneous Rocks & Depths of Earth ix. 189 The speeds of seismic waves cannot be said to demonstrate a peridotitic or *pyroxenitic layer between the 40-kilometer and 60-kilometer levels. 1979Nature 5 Apr. 545/1 Gorgona is one of the rare places in the world where young pyroxenitic komatiites exhibiting typical quenched spinifex textures..occur. |