透闪石质玉中黄玉与糖玉致色成因差异研究

采用常规宝石学仪器并结合电子探针、电子顺磁共振谱及紫外-可见光谱等测试方法,对软玉中不同深浅的黄玉与糖玉样品进行了系统分析,以探讨其致色原因及其差异。分析结果表明,黄玉的致色原因主要为O^2-→Fe³⁺的电荷转移跃迁及Fe³⁺的⁶A₁→⁴T₂（D）跃迁,糖玉则主要由Fe³⁺的⁶A₁→⁴E （D）、⁶A₁→⁴T₂（D）谱项跃迁与Mn³⁺的Jahn-Teller效应致色。黄玉中O^2-→Fe³⁺的电荷转移跃迁导致可见光区的412~500 nm处吸收,是形成与控制黄玉颜色的重要因素;而糖玉因含有Mn³⁺致使黄绿色光被吸收而显示出黄绿色的补色。此外,Fe²⁺—Fe³⁺的荷移与Fe²⁺（⁵T₂）+Fe³⁺（⁶A₁）→Fe²⁺（⁵E）+Fe³⁺（⁶A₁）跃迁也对糖玉和黄玉的致色具有贡献。     

次火山热变质煤的物理测试特征

样品采自伊敏褐煤盆地中一个因次火山活动形成的烟煤区,包含了从褐煤到瘦煤的变质系列。红外光谱分析表明,煤的含氧基团在褐煤阶段已开始消失,烷基和芳环同步增加,在R°=1.10%时达最大值。顺磁共振自由基浓度和X-衍射参数La/Lc介于区域变质煤和岩浆接触热变质煤之间,芳核外官能团的热演化超前于芳核骨架及R°的演化。     

变形煤的EPR结构演化及其构造地质意义

构造煤和高温高压实验变形煤的ＥＰＲ实验结果,充分显示了变形煤的ＥＰＲ参数具有随Ｒｏ,ｍａｘ的增大而呈现规律性演化的特征,在Ｒｏ,ｍａｘ〉４％以后煤结构演化机理向拼叠作用的转化在实验变形煤和构造煤中也有很好的体现。但是,变形煤Ｒｏ,ｍａｘ的增大除与温度和围压条件有关外,还深刻地受到定向压力或构造应力的影响,尤其是对镜质组反射率各向异性的增强、煤大分子结构有序畴及定向性的增大更具有极为重要的控制作用。     

Structure of volcanic glasses from the NMR-EPR perspective: a preliminary application to the Neapolitan Yellow Tuff

Glass samples from alkali-trachytic pumice of the Lower Member (LM, level LM1) and Upper Member (UM) of the Neapolitan Yellow Tuff at Campi Flegrei Caldera were studied by nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopy. The EPR data show that the relative occupancy of the different iron sites varies in samples from the Lower Member LM1 and Upper Member of the eruptive sequence. The LM1 glasses are characterized by a more homogeneous distribution of the cationic site population of iron compared with UM and by a different Fe³⁺/Al³⁺ substitution in the C_2v symmetrical sites of the silicate framework. ²⁹Si MAS NMR spectra on glasses indicate that LM1 glasses are more depolymerized than UM glasses, indicating the existence of structurally distinct magma batches. ²⁷Al MAS NMR spectra indicate the occurrence in UM glasses of aluminum in both tetrahedral and octahedral coordination; the observed Al^VI is believed to be a primary feature of the glass, since ²⁷Al CP-MAS NMR experiments do not reveal detectable esa-hydrated Al. The Al in sixfold coordination could be ascribed either to the more abundant alkali–OH terminations in UM, in which alkalies would be extracted from their charge-balance role for Al, thus altering its fourfold structural position, or to permanent compaction during fast cooling and decompression of high-pressure melts. ²³Na CP-MAS NMR experiments indicate the existence of Na–OH groups in both LM1 and UM glasses, relatively more abundant in the latter. Although preliminary, the results indicate the possible application of atomic-scale studies to variables that determine the regimes of explosive volcanism. Received: 1 July 1998 / Accepted: 1 October 1998     

珍珠层中的锰及其电子顺磁共振谱特征

采用原子吸收光谱及电子顺磁共振谱对我国4种主要育珠贝合浦珠母贝、大珠母贝、企鹅珍珠贝及三角帆蚌贝壳珍珠层中锰元素的含量其赋存状态进行了研究。结果表明各种贝类珍珠层中普遍含微量元素锰，其最大特点是淡水产珍珠层中的锰含量比海水产珍珠层普遍高1—3数量级。珍珠层的X-带电子顺磁谱(EPR)均在常温下显示了Mn^2 的超精细6重谱线信号，表明部分锰以Mn^2 形式位于石晶格中高度畸变的配位场中。     

构造煤的动力变质作用及其演化规津

采用X射线衍射分析、电子顺磁共振等方法研究了构造煤的动力变质作用特征和演化规律。构造煤与煤层的变形变质历史有关,动力变质作用形成的构造煤,其结构特征与其它变质类型煤不同,演化途径也不同,但它们的演化规律一致。      

Mineralogical Characteristics of the Separated Magnetic Rutile of the Egyptian Black Sands

The Egyptian black sands contain several economic minerals, such as ilmenite, magnetite, garnet, zircon, rutile and monazite. During the concentration and separation of a high-grade rutile concentrate a bulk magnetic fraction is obtained. This fraction is composed mainly of opaques, titanhematite, ilmenite–titanhematite exsolved intergrown grains, magnetic leucoxene in addition to chromite, and magnetic rutile. The magnetic rutile occupies 6 wt.% of the bulk magnetic fraction or approx. 4 wt.% of the original rutile content in the raw sands. Most of magnetic rutile crystals are contaminated with opaque inclusions, staining-coating and/or composite locked grains. This magnetic rutile has a magnetic range from strongly paramagnetic to very weak paramagnetic. Electron microprobe analysis for twenty-three magnetic rutile grains identified mineral components of rutile, titanhematite, pseudorutile, leached pseudorutile and ilmenite in decreasing order of abundance. Some other inclusions are also detected in the different magnetic rutile grains. They are most probably garnet, silica, amphibole, ilmenite, feldspar, mica and zircon. The presence of these inclusions reflect the derivation of magnetic rutile of various crystalline igneous and metamorphic rocks. The magnetic susceptibility of magnetic rutile depends on the associated mineral components and their relative volumes in comparison to the rutile mineral component. Magnetic susceptibility of magnetic rutile is also related to both type and size of the associated mineral inclusions. The average chemical composition of the magnetic rutile is 66.34 wt.% TiO₂, 21.71 wt.% Fe₂O₃, 6.39 wt.% SiO₂, 1.80 wt.% Al₂O₃, 1.19 wt.% CaO and 0.10 wt.% Cr₂O₃. Thus, the contamination of magnetic rutile in the non-magnetic rutile concentrate would decrease the market value of the rutile concentrate. Alternatively these magnetic rutile grains are recommended to be blended with magnetic leucoxene or some types of ilmenite concentrate to improve the overall marketable specifications especially for both of Ti, Fe and Cr contents.     

Caractérisation par résonance paramagnétique électronique (RPE) de quartz naturels issus de différentes sources

Natural quartz crystals coming from Madagascar, Angola, Brazil, and Spain were studied by EPR after β irradiation in order to characterise the paramagnetic centres due to impurities, and examine in which way their relative proportion could constitute a useful criterion for origin researches. In all our samples, EPR experiments revealed germanium centres [GeO₄/M⁺]° with M = Li or Na, aluminium ones [AlO₄/h]° and two titanium centres ([TiO₄/H⁺]° and [TiO₄/M⁺]°) also appeared, except for samples coming from Spain. The comparison of the relative concentrations of paramagnetic species led us on to draw diagrams that allowed distinguishing the origins of the studied samples using only EPR spectra. To cite this article: M. Duttine et al., C. R. Geoscience 334 (2002) 949–955.     

双向晶体旋转仪的研制及其在矿物学研究中的应用

本文介绍了双向晶体旋转仪的原理及研究情况，以及应用它研究金刚石，红宝石处在非立方对称时的杂质氮和铬的实验结果。     

白云石中Mn~(2+)及其占位的电子顺磁共振研究

本文用EPR法研究了白云鄂博矿床白云石中Mn~(2+)在Ca、Mg两个位置上的分配。通过比较白云石与菱镁矿中Mn~(2+)的精细结构线间的强度比,确定了几乎所有Mn~(2+)都处于Mg位置。其自旋哈密顿参数为:g=2.0022,A_∥=93.0×10~(-4)T,A_⊥=91.4×10~(-4)T,D=153.3×10~(-4)T。实验结果表明,白云石中Mn~(2+)的位置分配不取决于Mn~(2+)的浓度。离子半径和配位氧八面体畸变程度是控制位置分配的两个主要因素。