新疆色带电气石的生长过程及颜色起因研究

本文以新疆阿尔泰山地区花岗伟晶岩中的色带电气石为重点,应用X射线透射形貌技术,揭示了光学显微镜无法查明的结构缺陷,结合晶体表面微形貌观察及包裹体研究,阐明了色带电气石晶体的形成过程和生长机理。同时运用吸收光谱、穆斯鲍尔谱、红外吸收、核磁共振等谱学方法,对照光谱及化学分析、电子探针分析结果,对阿尔泰不同颜色的电气石晶体,特别是玫瑰色的颜色起因作了较全面的讨论。     

彩色电气石致色离子的化学状态研究

为探究不同颜色电气石中致色元素的化学状态及其化学环境,利用X射线光电子能谱方法对绿色调（墨绿色、蓝绿色、淡绿色）和粉红色调电气石样品进行分析。结果表明,绿色调和粉红色调电气石样品中均含有少量的过渡金属离子,如Fe,Mn,Ti,Cr,且不含Li和Be。不同颜色的电气石晶体中过渡金属阳离子的化学状态相同,且分别为Fe3＋,Mn4＋,Ti4＋,Cr3＋,但其与阴离子配位的环境有所差别。绿色调电气石样品中虽然Fe的质量分数有较大的差别,但均有部分Fe元素与F结合,即占据晶体结构中的Y位;粉红色电气石样品中,Fe离子没有与F形成配位,仅占据结构中的Z位。相反,在粉红色电气石样品中,Mn主要与F结合配位的方式存在,占据结构中的Y位,而绿色调电气石样品中大部分的Mn与O配位成键,只有少部分的Mn与F结合配位。由于Fe3＋,Mn4＋离子对之间电荷转移的可能性不大,故电气石的颜色可能主要由于d—d电子跃迁和氧与金属离子（O2--M）间电荷转移吸收引起,尤其是由于化学环境的差异（包括配位阴离子种类、杂质缺陷、结构畸变等）所引起。     

Crystallochemical effects of heat treatment on Fe-dominant tourmalines from Dolní Bory (Czech Republic) and Vlachovo (Slovakia)

Heat treatment was performed on selected Fe-dominant tourmalines to establish the nature of any change in optical properties. Two tourmaline samples from Dolní Bory, Czech Republic (TDB) and Vlachovo, Slovakia (TVL) were heated at 450, 700 and 900°C at 0.1 mPa and ambient oxidation conditions for 8 h. EMPA study shows that tourmaline from Vlachovo has schorlitic composition and tourmaline from Dolní Bory is alkali-depleted schorl to foitite. Although the black colour remained unchanged after heating at 450°C, it changed to brown at 700°C and reddish brown at 900°C. No significant changes of chemical composition were observed during heating. X-ray diffraction, infrared and Mössbauer study showed negligible oxidation of tourmaline heated at 450°C, but a significant change in iron valency state and deprotonization at 700°C. The oxidation of Fe is the main cause of tourmaline colour change, and the substitution vector for oxidation of Fe is Fe³⁺OFe _?1 ²⁺ (OH)_?1. The predicted deprotonization of OH was confirmed by infrared spectroscopy, which documented a decrease in OH groups in both samples, mainly at the V site. The oxidation of Fe is mostly significant in the Y site as documented on the compression of the Y-site octahedra and subsequent decrease in the a lattice parameter. This feature is consistent with lattice dimensions in the transition from schorl and foitite dimensions to those consistent with fluor-buergerite. The Z-site octahedra did not compressed and were not affected by heating-induced Fe oxidation, which indicates only negligible content of ^Z Fe²⁺ in original samples. After heating at 900°C, the tourmaline structure collapsed likely due to the thermally induced weakening of bonds in Y and Z octahedra, which results in amorphization of tourmaline. Subsequently, breakdown products including Fe-oxides and mullite replaced alkali-depleted amorphized tourmaline.     

我国电气石矿产资源开发前景分析

电气石是近年来开发的重要的新型功能矿物材料。文章论述了我国电气石矿产的类型、成矿特点及电气石矿产产出时空分布特征,表明我国具有电气石矿产资源优势。同时介绍了电气石矿物功能特性和电气石应用产品,展现我国电气石资源开发应用前景。     

Geochemistry and petrography of gold-quartz-tourmaline veins of the Okote area, southern Ethiopia: implications for gold exploration

Summary Quartz-tourmaline vein-hosting rocks of the Okote area belong to the Neoproterozoic Adola Belt. Metasomatic auriferous quartz-tourmaline veins occur in ductile N–S trending, sinistral shear zones. These veins commonly contain quartz, carbonates, and tourmaline, with minor pyrite, and accessory chalcopyrite, pyrrhotite, and gold. Tourmaline forms isolated euhedral crystals in the fracture surfaces of quartz carbonate veins. Many of the tourmaline crystals are optically zoned with a bluish core and a bluish to brown rim. Electron microprobe analyses show that the tourmalines comprise an intermediate dravite-schorl solid solution with a mean FeO/(FeO + MgO) = 0.47. Abrupt transitions between the colour zones within single tourmaline crystals are accompanied by relative variations in the FeO/(FeO + MgO) ratios. The tourmaline separates indicate that the tourmalines contain highly variable average contents of trace elements. Chondrite-normalized rare earth element (REE) abundances of tourmaline separates from auriferous veins show LREE-enriched to LREE-depleted patterns with negative to positive Eu anomalies and a flat, near-chondritic HREE pattern. The auriferous quartz-tourmaline veins have LREE-enriched patterns without a Eu anomaly and a flat HREE pattern, but tourmaline-free gold-quartz veins have very low REE contents and LREE-depleted patterns also without Eu anomalies. The FeO/(FeO + MgO) ratios, major and trace element compositions, and the types of wall-rock alteration are used to suggest that the sources of boron are dominantly metamorphic (dehydration and devolatilization processes), but do not totally exclude the possibility of a magmatic source. The occurrences of high-grade gold associated with tourmaline make tourmaline a valuable prospecting guide for hydrothermal gold mineralization in the Adola Belt, southern Ethiopia. Received November 17, 1999; revised version accepted July 23, 2001     

MANGANESE TOURMALINES

The role of manganese in the chemical composition and coloring of tourmaline is discussed. It is shown that manganese tourmaline-tsilaisite is similar to tourmaline-elbaite in composition and condition formation. The miscibility in the sherlite-elbaite-tsilaisite system is complete, but in the sherlite-dravite-tsilaisite system there is a gap between the dravite and tsilaisite, similar to the relationship between dravite and elbaite.

Manganese may be present in tourmaline in the form of Mn²⁺ and Mn³⁺. The pink coloring of the tourmaline is caused by Mn³⁺. This conclusion has been drawn from data provided by many authors on the nature of pink coloring of tourmaline, the dyeing properties of Mn²⁺ and Mn³⁺, the possibility of the existence of Mn³⁺ during the crystallization of pink tourmaline, and the distribution of manganese in differently colored tourmaline. --auth.     

Chemical compositions of tourmaline in the Yindongzi-Tongmugou Pb-Zn deposits,Qinling, China: Implications for hydrothermal ore-forming processes

A microprobe study has been carried out on the chemical composition of tourmaline from the Yindongzi and Tongmugou stratabound Pb-Zn ore deposits, eastern Qinling, China. Tourmaline was analysed from a variety of rock types representative of its various occurrences associated with the ore bodies. All the tourmalines studied here belong to the schorl-dravite series. Most are of hydrothermal origin with Mg > Fe and Na > Ca. Some detrital cores of tourmaline have been recognized from their geometry and chemistry, with Fe > Mg. The chemical trends from core to rim in zoned grains suggest a multi-stage model for the growth of tourmaline and genesis of the ore bodies. The first stage was represented by a more Mg-rich hydrothermal fluid in the submarine hydrothermal system, producing Mg-rich tourmalines by selective replacement of clay-rich sediments close to the sediment-water interface. The second stage was dominated by Fe-rich hydrothermal fluid and resulted in overgrowth of Fe-rich tourmaline rims. This stage also led to the nucleation and growth of new tourmaline crystals and was responsible for the formation of the main massive sulphide orebodies. Finally, a further period of hydrothermal activity or a metamorphic event led to the formation of an additional rim of Mg-rich tourmaline.     

东秦岭花岗伟晶岩中电气石地球化学特征及成矿指示意义

东秦岭地区是我国重要的花岗伟晶岩区及稀有金属成矿区.电气石在东秦岭各类花岗伟晶岩中广泛发育,通常在无矿化伟晶岩、铍矿化及锂矿化伟晶岩中呈黑色-深蓝色.本文旨在通过各类伟晶岩中电气石的对比研究揭示电气石地球化学特征对东秦岭伟晶岩矿化类型的指示作用.本文所研究电气石为作为东秦岭各类伟晶岩贯通矿物的黑电气石系列.在双峰村、碾...     

Mineral chemistry of tourmaline from Mashak Pahar,South Purulia Shear Zone (SPSZ), eastern Indian Shield

The area of investigation at and around Mashak Pahar, Bankura district, West Bengal, India comprises a number of rock types namely: granite gneiss, migmatized quartz tourmaline gneiss, quartz pebble conglomerate, ferruginous quartzite, quartz tourmaline veins (as veins) and graphite schists. Interestingly, the study area lies in the region extending South Purulia Shear Zone (～Tamar–Porapahar Shear Zone) which marks the boundary between two contrasting tectonic blocks of eastern India, namely, the Chhotanagpur Gneissic Terrane (CGC) to the north and Singhbhum Group of rocks to the south. The rocks of the study area are poly-phasedly deformed by three phases of folding, namely, F₁, F₂ and F₃. All the tourmalines are classified to be of ‘Alkali Group’. Chemistry of tourmalines from migmatized quartz tourmaline gneiss and those from quartz tourmaline veins are in conformity with their relation to (earthquake induced) shear system evolution in this terrain. In general, the compositional evolution of tourmaline during prograde metamorphism (～400°–730°C) has been supported by both petrographic and chemical evidences. Assessment of mineral–chemical data of constituent tourmaline grains clearly suggests compositional variations across zonal boundaries within tourmaline that was controlled by changing metamorphic milieu in this terrane. Field and petrographic evidences clearly indicate activation of earlier and later shears in this region accompanied by infiltration of boron and formation of zoned tourmaline crystals.     

我国电气石矿床类型及其地质特征

在研究我国电气石矿产产出地质环境、成矿地质过程和电气石矿物组分特征的基础上,总结了我国电气石矿产成矿类型：花岗伟晶岩型、岩浆热液型、火山次火山热液型、热水沉积型和表生残积砂矿型。并阐述了各类型电气石矿床类型产出的时代、成矿地质特征和电气石矿物化学特征。     

电气石——成岩成矿作用的灵敏示踪剂

本文详细论述了电气石的化学组成（主化学元素、微量元素和稀土元素）和同位素组成Ｈ、Ｏ、Ｂ、Ｓｉ、Ｒｂ／Ｓｒ、Ｓｍ／Ｎｄ、ｐｂ／ｐｂ和Ｋ／Ａｒ）特征,提出电气石可以作为研究成岩成矿作用的一个灵敏示踪剂。利用电气石的主化学元素和微量、稀土元素组成,可以有效指示其形成的物理化学环境,还可以作为一种有用的找矿标志,指标矿化的存在,并可能用于区分矿化类型和矿体规模。电气石的稳定同位素和放射性同位素研究,已经用     

广西大厂地区黑云母花岗岩中电气石的化学组成及其对岩浆热液演化的指示

广西大厂地区笼箱盖黑云母花岗岩与区内晚白垩世锡多金属成矿作用在时空上密切相关。岩相学特征表明,笼箱盖黑云母花岗岩中的电气石可以分为三类:1)浸染状电气石; 2)石英-电气石囊; 3)电气石-石英脉。本文利用电子探针和激光剥蚀等离子体质谱系统测定三种不同产状电气石的化学组成。分析结果显示,三种产状的电气石均具有高的Fe/(Fe+Mg)和Na/(Na+Ca)比值,主体属于碱基亚类铁电气石。浸染状电气石为岩浆晚期结晶,其Fe/(Fe+Mg)比值变化于0. 85～0. 94,随着岩浆分异,电气石逐渐富集Li、F、Fe和Sn等元素。与浸染状电气石相比,石英-电气石囊中早阶段电气石具有低的Fe/(Fe+Mg)比值,高的V、Co和Sr含量,可能反映了岩浆演化晚期出现的不混溶富硼熔/流体对早期黑云母和长石的交代作用,从而使囊中早阶段电气石继承部分被交代矿物的化学组成特征;石英-电气石囊中晚阶段电气石的化学组成变化较大(如Li、F、Mg、Al、V、Fe和Zn),与热液成因电气石的推论一致。与浸染状和囊状电气石相比,石英脉中的电气石具有高的Fe/(Fe+Mg)和Na/(Na+Ca)比值;微量元素组成与囊状电气石相似。就成矿元素锡而言,三种产状的电气石均具有相对高的锡含量,与其他地区锡成矿花岗岩中电气石的成分特征相似。但是,从岩浆晚期到热液阶段,大厂地区电气石的锡含量并没有显著升高,可能反映了早期岩浆热液流体对熔体锡有限的萃取作用。     

Fluid inclusion study of gem tourmaline from Xinjiang,China

Reported in this paper are the results of geological and fluid inclusion studies of gem-grade tourmaline in pegmatite veins from Altay, Xinjiang. The homogenization temperatures of fluid inclusions in the tourmaline range from 230° to 350°C with a salinity of 0.2−4.5 NaCl% equiv. The composition of fluids corresponds to the NaCl-CaCl₂-H₂O system in terms of the measurements of first melting temperature of fluid inclusions. By comparing the homogenization temperatures of different color zones in the gem tourmaline, it is suggested that it has undergone an intermittent growth process. Careful observation of the section parallel to thec axis of greenish blue tourmaline provides evidence of the occurrence of cat-eye tourmaline similar to that found in Brazil and other parts of the world. Attention should be paid to such kind of tourmaline as viewed from its economic importance.     

Changes in tourmaline composition during magmatic and hydrothermal processes leading to tin-ore deposition: The Cornubian Batholith,SW England

To investigate the potential of tourmaline as a geochemical monitor, a comprehensive dataset on major, minor and trace element concentrations as well as Fe³⁺/ΣFe ratios of tourmaline is presented. The dataset includes samples from five plutonic complexes related to diverse magmatic to hydrothermal stages of the Cornubian Batholith (SW England). Tourmaline composition found in barren and cassiterite-bearing samples include all three primary tourmaline groups and tourmaline species with the general endmembers schorl, dravite, elbaite, uvite, feruvite, foitite and Mg-foitite.Based on textures and compositions, it is possible to distinguish not only between late-magmatic and hydrothermal tourmaline, but also between several formation stages. Hence, tourmaline monitors late-magmatic processes and the partitioning of elements during exsolution of an aqueous phase. For example, in hydrothermal tourmaline Sn is strongly enriched, while Ti, Cr, V and Sc are depleted compared to late-magmatic tourmaline of the same sample. Several tourmaline generations that precipitated from magmatic fluids can be distinguished with differing major and minor elements and REE patterns depending on the composition of the melt from which they were expelled from. Strongly zoned tourmaline allows for unraveling the hydrothermal history of a distinct location including ore precipitation. The precipitation of SnO₂ in the study area was probably caused by mixing between acidic, reduced, Sn-bearing magmatic fluids and oxidized meteoric fluids, which is in agreement with London and Manning (1995) and Williamson et al. (2000). Hence, the ability of tourmaline composition to monitor changes in Sn concentration and redox conditions in hydrothermal fluids has potential as an exploration tool.     

电气石红外光谱和红外辐射特性的研究

精确测试和研究了不同种属电气石的红外光谱特征及不同种属、不同温度条件下热处理电气石的红外辐射特性。结果表明：电气石具有高红外发射率的本质在于其晶体结构中的分子振动具红外活性;铁、镁电气石红外发射率相近,且都大于锂电气石的红外发射率;电气石热处理的温度与红外发射率之间存在一定的对应关系,随着热处理的温度的增加,红外发射率减小,当温度增大到800℃红外发射率达到最大值,超过900℃,电气石开始分解,红外发射率开始下降;电气石在室温下最大单色辐出度相应的波长为9~10μm 与绝对黑体9.72 μm 吻合较好,为良好的红外吸收与发射材料。     

Genesis of yellow manganese-rich elbaite from the Canary mining area,Lundazi, Zambia

The most important source of yellow gem elbaite is the Canary mining area in the Lundazi District of eastern Zambia. The tourmaline has been mined since 1983 from both pegmatite and eluvial/alluvial deposits, in colors typically ranging from yellow-green to yellow to orange and brown; much of the orange-to-brown material is heated to attain a ‘golden’ or ‘canary’ yellow color. The elbaite is Mn-rich (up to 9.18 wt% MnO documented in the literature) and contains small amounts of Ti and little or no Fe. The distinctive composition of this tourmaline is probably the result of the early crystallization of abundant schorl from an unusual B-rich, Li-poor pegmatite melt, which depleted Fe while conserving Mn until the late-stage crystallization of gem pockets. The simple mineralogy of the pegmatite consists of feldspars, quartz, and tourmaline; the lack of micas, phosphates, or Li minerals, and the presence of very little garnet, allowed Mn to fractionate to high levels during pegmatite crystallization. The presence of abundant gem tourmaline in a Li-poor pegmatite is highly unusual.     

我国电气石资源分布、地质特征及其开发利用前景分析

电气石因具有压电性、热电性、存在自发永久电极及具较高的红外辐射能力等特征,在日本、美国、韩国等国家已开发出相应的系列产品,应用于环境保护、保健及电子工业领域。文章在系统查阅国内文献的基础上,初步分析了我国电气石资源概况及地质特征,指出我国的电气石矿产具有资源较丰富、分布较广泛又相对集中的特点。文中还介绍了国内外电气石研究开发现状,指出电气石将成为21世纪的新型功能性材料,提出了我国电气石开发利用对策。     

西藏错那洞电气石花岗岩中电气石化学组成、硼同位素特征及意义

为了对西藏错那洞电气石花岗岩源区进一步约束,利用显微镜、电子探针和激光剥蚀多接收等离子质谱仪,对错那洞电气石花岗岩中电气石的形态、成分及硼同位素组成进行了研究.结果表明,错那洞电气石花岗岩中的电气石为碱族黑/铁电气石,直接结晶自富硼熔体,与熔体之间未发生明显的硼同位素分馏.电气石δ11B值主要在-6.91‰^-9.17‰之间,与大陆地壳平均δ11B值(-10‰±3‰)相近,表明错那洞电气石花岗岩主要源自变质沉积岩的部分熔融.然而,与起源于变质沉积岩的花岗岩相比,样品的δ11B值明显偏高,而与前人报道的雅拉香波淡色花岗岩(源自石榴石角闪岩部分熔融)的δ11B值相似.因此,错那洞电气石花岗岩源区中,除了变质沉积岩外,可能还混入了少量石榴石角闪岩.     

Tourmaline composition and boron isotopes record lateritic weathering during the Great Oxidation Event

Identifying evidence of oxidative weathering in the geological record is essential to trace the evolution of Earth's atmosphere oxygenation. Metamorphosed residues of lateritic weathering have been identified as two rock types in the 2.1‐Ga‐old Cercadinho Formation, Piracicaba Group, Quadrilátero Ferrífero of Minas Gerais. One is tourmaline–hematite–sillimanite–kyanite quartzite; the other is rutile–tourmaline–hematite–muscovite phyllite. Both rocks have abundant tourmaline with δ¹¹B values between about ?17‰ and ?13‰. The Cercadinho tourmaline is roughly parallel to the povondraite–“oxy‐dravite” join of meta‐evaporitic tourmaline, in its more aluminous segment, offset to higher contents of iron. These compositional and isotopic characteristics of the Cercadinho tourmaline indicate that continental evaporitic brines interacted with aluminium‐ and iron‐rich residues of lateritic weathering. The abundance of disseminated tourmaline, a mineral poorly reported from palaeosols worldwide, implies a boron‐rich brine overprint on the lateritic profile before the onset of metamorphism, reflecting a climatic change from humid to arid conditions in a continental setting. The recognition of lateritic weathering in the Cercadinho Formation contributes to the amount of evidence for increased levels of atmospheric oxygen between 2.22 and 2.06 Ga ago.     

电气石的电场效应及其在环境领域中的应用前景

电气石具有永久性的自发电极,电气石微粒的周围存在着以c轴轴面为两极的静电场.在电场作用下,水分子发生电解,形成活性分子 H3O+,吸引水中的杂质、污垢,净化水质;OH- 和水分子结合形成负离子,改善人们的生活环境;电场对带电粒子有吸附作用,可以吸附粉尘,净化空气.电气石还具有高的机械化学稳定性,与沸石、蒙脱石等的吸附作用相比,电气石不具有饱和极限,可持续使用,重复利用率高,在环境领域具有很好的发展前景.