福建龙岩风化型高岭土矿床中粘土矿物的研究

福建龙岩高岭土矿床风化剖面各风化带有特征的粘士矿物组合。高岭矿物在风化剖面中由下而上逐渐增多,反映出花岗岩中原生矿物高岭土化程度逐渐加强的阶段性变化。高岭石结晶较差,以薄片状或具长石、云母假象的大于2um粒级出现。埃洛石为7或10型,多富集在小于2um粒级中。埃洛石结晶形态的多样性及多变性与矿物形成时的物质来源及水化状态有关。长石蚀变为高岭矿物,可以经由水铝英石向球状或管状埃洛石直到高岭石的转变、长石的固态转变和从溶液中直接结晶等几个途径。白云母的高岭土化能直接转变为具云母假象的高岭石。     

醴陵高岭土矿的矿物组成及其风化特征研究

醴陵高岭土是优质的陶瓷原料,优质矿石主要由印支晚期的石英斑岩经风化作用形成。矿石的主要矿物包括高岭石、埃洛石、水云母、石英和少量蛭石。根据风化作用强度差异,可将高岭土风化剖面分成半风化带、风化骷和风化残积带。各带矿物组合和主要矿物组分都呈规律性变化,风化作用的最终发展趋势是向着形成高岭土矿物的方向进行。在风化剖面发育过程中起重要作用的是母岩的结构、成分及水介质的性质。     

龙岩高岭土矿床地质特征及成矿作用

福建龙岩高岭土矿床是蚀变花岗岩风化残余型矿床。花岗岩风化剖面具有明显的垂直分带性，各带有特征的粘土矿物组合、含量和化学组分。矿石矿物主要有高岭石、埃洛石、水白云母、石英及少量长石。高岭石的结晶有序度较低，粒度一般大于２μｍ。埃洛石粒度多小于２μｍ．龙岩高岭土矿石具有贫铁、钛和自然白度高的特征，属优质大型高岭土矿。其成矿作用经历了内生岩浆分异、热液蚀变和表生风化三大地质作用。     

苏州高岭土矿成矿期后的矿物演化及其与矿体改造的关系

苏州高岭土矿主要由高岭石、7埃洛石、10埃洛石及少量绢云母、蒙脱石、明矾石、三水铝石组成。高岭土矿物形成后因外界地化条件改变发生了以下转变:(1)埃洛石脱水向高岭石转化;(2)次生淋滤埃洛石形成;(3)埃洛石和三水铝石之间的互相转化;(4)Ca型蒙脱石形成;(5)高岭土的磷酸盐化作用;(6)次生淋滤明矾石的形成。矿物生成的先后顺序和共生关系可将矿物形成分为主要成矿期和成矿期后演化两个阶段。矿物的后期演化使优质高岭土进一步富集,改造,形成量大质优的高岭土矿。同时,非高岭土矿物的生成又使部分矿石质量变差,降低了矿石的工业价值。     

江西龙南花岗岩稀土风化壳中粘土矿物的研究

本区燕山早期花岗岩发育的风化壳中的粘土矿物以高岭石和埃洛石(7Å)为主;蒙脱石、三水铝石及其它为新查明矿物。据粘土矿物组合特征,自风化剖面深部到地表分为三个带:含蒙脱石带,高岭石和埃洛石(7Å)带,含三水铝石带。本文探讨了矿物在风化过程中的生成演化顺序,并进行了热力学的解释。据各带粘土物质的阳离子交换量与稀土含量变化的不一致关系认为,稀土在C带中的富集是化学风化的结果,与粘土矿物组合无关。     

高岭石和埃洛石-7Å对稀土元素吸附特征的实验研究

针对赣南风化淋积型稀土矿中稀土元素的分异现象,通过研究该稀土矿的主要矿物成分——高岭石和埃洛石-7的矿物特征及其在不同条件下的吸附特征,探讨了该类型稀土矿的成矿机制和稀土元素分异机理。高岭石和埃洛石-7吸附稀土元素的能力受体系p H值以及金属阳离子钾、钠的的影响,且埃洛石-7吸附稀土元素的能力高于高岭石。横向对比实验结果表明当体系中赋存有K+时,两种粘土矿物对稀土元素的吸附呈现出分化趋势,其中高岭石主要吸附中-重稀土元素,埃洛石-7反之,因此风化淋积型稀土矿风化过程中释放出的K+可能会使高岭石和埃洛石-7呈现出差异吸附特征,进而反过来影响稀土矿中稀土元素的配分。     

风化型和含煤建沉积型高岭土的物质组成对比研究

我国高岭土资源丰富,矿床类型多,其中风化和含煤建造沉积型是两类比较重要的高岭土矿床,对这两类高岭土矿床化学组成,矿物组成及高岭石矿物学特征的异同点进行研究和探讨,其结果表明,风化高岭土的化学成分一般属硅高铝低型,钾含量偏高,钛含量低,铁含量则随成矿线岩和风化条件的不同波动范围大,矿物组成主要为结晶度较差的高岭石、水云线和石英,以及极少量的管状埃洛石,含煤建造沉积型高岭土一般属铝高硅低型,钾含量低,钛含量明显偏高,矿物组成简单,高岭石含量〉９５％,结晶度较好。     

叙永式埃洛石矿中矿物演化的研究

川、黔、滇交界处的埃洛石矿俗称“叙永石”,产于上二叠乐平统龙潭页岩和下二叠阳新统茅口灰岩的卡斯特侵蚀面间。成矿母岩为上二叠乐平统含黄铁矿的高岭石粘土岩。母岩在风化淋滤期间经历以下变化:(1)黄铁矿氧化成针铁矿;(2)高岭石从有序向无序转化,最终转变成埃洛石;(3)锐钛矿作为稳定相残留富集于剖面上部。形成的矿物组合以10埃洛石为主,包括伊利石、伊利石/蒙脱石混层矿物、三水铝石、三羟铝石、石膏、水铝英石和石英。     

广西合浦新屋面高岭石矿物学特征及其形成途径

在野外实地考察的基础上,结合X射线衍射、扫描电镜(SEM)、化学成分分析等测试技术,对广西合浦新屋面高岭土矿床的风化物进行了研究。X射线衍射分析表明,黏土矿物主要为高岭石、伊利石、石英、正长石及斜长石。高岭石结晶度在0.489～1.210之间,随着深度的逐渐减小,高岭石逐渐增多,长石逐渐减少,高岭石的结晶程度则呈现变好的趋势,反映出花岗岩中原生矿物高岭土化程度逐渐加强。SEM结果表明,随着风化程度的加强,高岭石发育越来越好,晶形越来越完整。化学成分分析显示w(Al2O3)和w(K2O)互为消长关系,且随着深度的增大,Al2O3逐渐减少,K2O逐渐增多。该区长石蚀变为高岭土,可以经由绢云母中间阶段再转变形成高岭石和直接转变形成高岭石这两个途径。     

赣南花岗岩风化壳型稀土矿床中纳米级稀土矿物的研究

为揭示次生风化成因稀土矿物的赋存形态和分布特征,对赣南安远岗下稀土矿区花岗岩风化壳剖面进行了研究。采集风化壳不同层位的样品进行分选、提纯,场发射扫描电镜和透射电镜研究结果表明,与稀土矿物紧密相关的粘土矿物是高岭石和埃洛石等,风化壳中发现的纳米级稀土矿物既有附着于其他矿物表面的微细颗粒,也有呈集合体存在的稀土矿物(可能为方铈石),这一现象有助于进一步认识风化壳稀土矿床的形成过程。     

苏州阳西风化型高岭土矿物的形成与演化

苏州高岭土矿床可划分为两种成因类型^[1,2],即风化型¹⁾和热液蚀变型。高岭土集中分布在阳山东、西、北三个矿区。本文仅就阳西风化型高岭土中产出的不同种类高岭土矿物的形成及其互相演变的关系作初步探讨。     

贵州碳酸盐岩红土中的粘土矿物及其形成机理

本文运用Ｘ射线衍射、红外光谱、差热、透射电镜和扫描电镜等方法对贵州碳酸盐岩红土中的粘土矿物进行了系统研究。高岭石和０．７ｎｍ埃洛石是碳酸盐岩红土中的主要粘土矿物，其次为伊利石、蛭石、绿泥石、绿泥石／蛭石混层矿物，水铝英石和三水铝石等。     

高岭石-多水高岭石演化系列的热谱特征

高岭石-多水高岭石演化系列共包括四种矿物:结晶良好的高岭石、结晶差的或b轴无序的高岭石、7Å多水高岭石和10Å多水高岭石。我们将结晶良好的高岭石和10Å多水高岭石分别视为这一演化系列的两个端元矿物,其余两种矿物则是演化系列的中间矿物。该系列中的矿物同属于1:1型含水的层状铝硅酸盐矿物,因而它们的化学成分基本相同,主要差别是在晶体结构上由于单位结构层沿c轴彼此堆叠的方式而引起从有序向无序变化,同时层间键力的减弱引起水分子进入,促使层间水的含量逐渐增大。基于以上特征,这一系列中的四种类型矿物受热以后的热效应很灵敏,详细研究它们在加热脱水过程中的变化规律,可以加深对矿物特性的认识和鉴别。     

高岭石-多水高岭石矿物晶体形态与演化

通过对我国南方许多风化型高岭土矿床研究查明,在表生条件下形成高岭石-多水高岭石矿物的基本因素是决定于风化母岩的岩性和水介质的物化性质。水介质的物化性质又明显地受到风化母岩的岩性类型和结构构造、动力裂隙的发育程度、围岩的稳定性和透水性、气候、地形地貌和植被等因素的综合性制约。     

Kaolin Occurrences in the Erenler Dagi Volcanics,Southwest Konya Province,Turkey

Mainly calc-alkaline, andesitic, and dacitic volcanics from different late Miocene-Pliocene eruption centers crop out WSW of Konya, and locally are interbedded with lacustrine sediments. Hydrothermal alteration within these rocks is widespread. In addition to kaolinite, other major alteration products include halloysite, alunite, cristobalite, quartz, illite, montmorillonite, and zeolitegroup minerals. Based on the cristobalite-quartz relationship, the kaolinization temperature is estimated as ～100°C.

The samples were mineralogically and chemically examined using XRD, SEM-EDS, IR, DTA-TG, and XRF. The crystallinity of the kaolinite is moderate, and shows structural disorder. Both the kaolinite and halloysite are almost stoichometric. Kaolinization generally led to Al₂O₃ increases and release of alkalies, alkaline earths, most of the Fe₂O₃, and SiO₂. SiO₂ and Al₂O₃ contents are low, and LOI is very high for halloysite deposits relative to kaolin occurrences. The kaolinite-alunite assemblages indicate that pH of the altering solutions initially was ～4. SEM investigation demonstrates that kaolinite has booklet texture, whereas halloysite is acicular to needleshaped. The chemical, mineralogic, and firing properties of the kaolin deposits are appropriate for use as refractory raw material. The Erenler Dagi kaolin deposits are excellent examples of the acid-sulfate type of hydrothermal alteration. The findings of the study may be useful in exploration for similar hydrothermal mineral occurrences worldwide.     

The South Ushkoty Eluvial Kaolin Deposit in the Southeastern Orenburg Region

The South Ushkoty eluvial kaolin deposit discovered and explored by the authors is situated 20 km away from the railway in the Dombarov district of the Orenburg region. The deposit is localized in the axial zone of the East Ural Uplift. Leucogranites of the Upper Ushkoty Pluton serve as bedrocks. The deposit comprises five lodes, among which the largest deposit has a reserve of 40 Mt. The lodes are erosion remnants of the well-developed linear-areal weathering zone related to the fragments of Mesozoic peneplain at the hypsometric level not lower than 360 m. Variation of the kaolin zone thickness, the entire weathering zone, and the deposit morphology is largely governed by the nearly meridional and northeastern faults. Two productive zones—the normal kaolin (kaolinite + quartz) zone and the alkaline kaolin (kaolinite + quartz + potassium feldspar and/or muscovite) zones—are recognized in the weathering profile of leucogranites of the Upper Ushkoty Pluton. The alkaline kaolin is of commercial significance as a complex raw material if the potassium oxide content is above 3.5%. The composition and properties of the concentrated kaolin meet the requirements of its traditional consumers (fine ceramic works, paper mills, and others). The discovery of the South Ushkoty deposit confirmed the previous forecast on considerable prospects of the Orsk Transural region for kaolin. We hope that this discovery will stimulate the further investigation and assessment of resources in the Mugodzhary kaolin-bearing subprovince.     

Kaolin deposits at Melthonnakkal and Pallipuram within Trivandrum block, southern India

The kaolin deposits at Melthonnakkal and Pallipuram mines form part of the Warkalli Formation belonging to the Tertiary sequence in southern Kerala and occur at the boundary between the Tertiary sequence and Precambrian granulite facies metapelites (khondalites). The sedimentary clays are composed mainly of kaolinite, quartz and gibbsite. XRD and SEM studies have revealed that kaolinite is well-crystallized variety and the platy crystals are scarcely broken in the sedimentary clays. These sedimentary kaolins are considered to have been formed by intense tropical weathering of the khondalites, and subsequently transported and deposited with high organic input into lakes near the weathering crust over the basement rock. Besides, the surficial parts of the sedimentary deposits are extensively lateritized with the formation of goethite and hematite by Quaternary tropical weathering processes.     

Origin of the Matauri Bay halloysite deposit, Northland, New Zealand

At the Matauri Bay halloysite deposit, economically valuable halloysite-rich clays are hosted by a sanidine rhyolite dome (Ar–Ar dated at 10.1?±?0.03?Ma). The rhyolite dome intrudes an older basalt and is overlain by alluvial sediments and a younger basalt (4.0?±?0.7?Ma). A blanket-like, halloysite-rich zone is restricted to depths of 10–30?m from the present day erosion surface. Primary sanidine and plagioclase phenocrysts in rhyolite are completely leached out in the halloysite-rich zone but are only partially leached out at greater depth. Halloysite was formed by hydrolysis and cation leaching of sanidine and plagioclase phenocrysts and groundmass glass in the rhyolite, resulting in loss of K, Ca, Na and Si and enrichment in OH (LOI 6–10%) and Al₂O₃ (20–30%) relative to least-altered rhyolite with 1.8% LOI and 14.5% Al₂O₃. Oxygen and hydrogen isotope data indicate the halloysite is supergene rather than hydrothermal in origin, which is consistent with the absence of pyrite, alunite and other acid-sulphate type hydrothermal minerals, and with the blanket-like alteration profile. The dominance of halloysite over kaolinite was favoured by water-saturated weathering conditions during the late Miocene-Pliocene subtropical weathering regime in Northland.