Scandiobabingtonite, a new mineral from the Baveno pegmatite, Piedmont, Italy
Scandiobabingtonite, a new mineral from the Baveno pegmatite, Piedmont, Italy
复制标题
Scandiobabingtonite，一种来自意大利皮埃蒙特巴韦诺伟晶岩的新矿物
DOI：
10.2138/am-1998-1222
复制
发表时间：
1998
影响因子：
3.1
通讯作者：
G. Vezzalini
中科院分区：
文献类型：
--
作者：
P. Orlandi;M. Pasero;G. Vezzalini
摘要 钪狒狒石（Ca2(Fe2+,Mn)ScSi5O14(OH)）是狒狒石的钪类似物；它是在巴韦诺花岗岩的伟晶岩空腔中发现的，与正长石、钠长石、白云母、辉长石和萤石有关。其光学器件为双轴 (+)，2V = 64(2)°、a = 1.686(2)、b = 1.694(3)、g = 1.709(2)。 Dmeas = 3.24(5) g/cm3，Dcalc = 3.24 g/cm3，Z = 2。Scandiobabingtonite 无色或浅灰绿色，透明，具有玻璃光泽。它以亚毫米大小的短板状晶体形式出现，在 [001] 上稍微拉长，其特征是形式 {010}、{001}、{110}、{1 1̅0} 和 {101} 的关联。它也以薄边缘的形式出现，上面包裹着小块的黄铝铜矿晶体。 X 射线粉末图中最强的线位于 2.969 (S)、2.895 (S)、3.14 (mS) 和 2.755 (mS) Å。该矿物为三斜晶系，空间群P1̅，a = 7.536(2)，b = 11.734(2)，c = 6.748(2) Å，α = 91.70(2)，β = 93.86(2)，γ = 104.53(2)°。 Scandiobabingtonite 与 babingtonite 是同构的，Sc 以六重配位取代了 Fe3+，但 Sc 没有取代 Fe2+。由于新物种缺乏合适的大晶体，通过使用单晶 X 射线衍射 (XRD) 数据细化富钪黄锰矿（最终 R = 0.047）的晶体结构，已经证实了这种替代。
Abstract Scandiobabingtonite, ideally Ca2(Fe2+,Mn)ScSi5O14(OH) is the scandium analogue of babingtonite; it was found in a pegmatitic cavity of the Baveno granite associated with orthoclase, albite, muscovite, stilbite, and fluorite. Its optics are biaxial (+) with 2V = 64(2)°, a = 1.686(2), b = 1.694(3), g = 1.709(2). Dmeas = 3.24(5) g/cm3, Dcalc = 3.24 g/cm3, and Z = 2. Scandiobabingtonite is colorless or pale gray-green, transparent, with vitreous luster. It occurs as submillimeter sized, short, tabular crystals, slightly elongated on [001], and characterized by the association of forms {010}, {001}, {110}, {1 1̅0}, and {101}. It occurs also as a thin rim encrusting small crystals of babingtonite. The strongest lines in the X-ray powder pattern are at 2.969 (S), 2.895 (S), 3.14 (mS), and 2.755 (mS) Å. The mineral is triclinic, space group P1̅, with a = 7.536(2), b = 11.734(2), c = 6.748(2) Å, α = 91.70(2), β = 93.86(2), γ = 104.53(2)°. Scandiobabingtonite is isostructural with babingtonite, with Sc replacing Fe3+ in sixfold coordination, but no substitution of Fe2+ by Sc takes place. Due to the lack of a suitably large crystal of the new species, such a replacement has been confirmed by refining the crystal structure of a Sc-rich babingtonite (final R = 0.047) using single-crystal X-ray diffraction (XRD) data.