Blue John fluorspar

Of the many varieties of fluorspar found in the Peak District of Derbyshire, by far the best known is Blue John, long used for the manufacture of a variety of ornaments and jewellery.     

Die Flußspatlagerstätten Asturiens/Nordspanien und deren Genese

The fluorspar deposites described are located within the permotriasic basin of Western Asturias/Northern Spain. The block-faulted basin is bordered in the south by the Cantabrian Mountainrange, folded in Hercynian times. The fluorspar deposites overlie the strata of this paleozoic base and the fluorspar-layers dip gently to the North at 10 to 15?. They are related to the angular unconformity between the mostly eroded Paleozoic rocks and the overlying, mainly red, Permotriasic sediments. Volcanic rocks apear only in few places, where they are intercalating more ore less the upper parts of triasic strata, reddish shales of “Keuper” age. The occurrences fluorspar-layers are found mainly in the uneroded areas where the basal Permotriasic is still preserved on the old Permian land surface, underlain preserved on the old Permian land surface, underlain mostly by Devonian and lower Carboniferous limestones, marls and shales. A special rock type, a breccia between the foulded Paleozoic base and the unfolded Permotriasic sediments forms a marker horizon, thought to have originated from the fracturing of the underlaying Paleozoic rocks. The genesis of fluorspar and breccia is thought to be connected with the formation of a peneplain-like land surface and its repetated uplift and depression, i. e. repeated flooding by sea and subsequent emergence. Light-grey to reddisch sand- and siltstones as well as small pebble conglomerates were deposited in erosion channels and karst holes, sometimes extending through the breccia down into the massiv lower Carboniferous and Devonian base. It is in these sediments, that the fluorspar is found to produce dispersed or in massiv form sheet-like and flat-lying bodies as well as channel-like, occurrences. In areas of strong post, Permian tectonic movements the stratabound mineralisation were sometimes mobilized to form dike-like deposites. The morphological and petrological structure, e. g. the complete lack of primary zoning even in dike-like deposites, and the geological situation as a whole contradict the opinion of G.Einecke (1956) that these fluorspar deposites originated from hydrothermal solutions, emanating from plutonic or volcanic rocks. Geochemical investigations of soil samples and drill cores from Paleozoic rocks point to the origin of fluorine from Devonian and Carboniferous, rich in organisms (Coal-strata) and consisting of shales marls and limestones (or even older rocks) which were eroded and redeposited in Permian times.     

Rare earth elements distribution in fluorites and carbonate sediments of the east-alpine mid-triassic sequences in the Nördliche Kalkalpen

Controversial genetical interpretations on the fluorite occurrences in the leadzinc deposits of the Nördliche Kalkalpen led to the present study. The distribution of the rare-earth elements (REE) in the fluorspar-carbonate assemblages and the fluorspar separates have been determined non-destructively by means of instrumental neutron activation analysis using high resolution γ-spectrometry. A geochemical model describing the distribution of the REE in the two mineral phases of CaCO₃ and CaF₂ formed syngenetically under marine conditions has been built up in order to elucidate the observed REE abundances in the carbonates and their fluorspar separates. The low and comparable concentrations of REE, the similarity in their relative distribution patterns in carbonate-fluorspar assemblages as compared to those in carbonate sediments observed by other authors and the sedimentary characterization via the Tb/Ca-Tb/La relation criterion revealed by the present study unequivocally suggest a synsedimentary nature of the fluorspar. In addition, the study showed that a diagenetic recrystallization results in a further fractionation of Tb and La with a preferential improverishment in La. Such a phenomenon opens a possible geochemical criterion for the identification of different generations of fluorspars.     

A neutron activation technique for the analysis for fluorine in fluorspar samples

This article explains the results of the feasibility study about using neutron activation technique via Deferred gamma rays, to analyze the fluorine content in a sample from a fluorspar concentration plant. The theoretical responses of 12 items, constituting the samples have been analyzed. 468 reactions have been obtained from the study with the database EXFOR of these elements with neutrons from an Americium Beryllium source of 1 Ci activity.The radioactive decay of 29 products, anticipated from such an activation, has also been analyzed. From these results, a prototype for neutron activation has been designed. The different criteria of the measurement procedure to enable the activation of the fluorspar samples and to record their spectra with minimal interference from the source have been adjusted. A mathematical model of the activation response has been created and validated. The activation method to determine the fluorine content in fluorspar samples proved to be scientifically and technically feasible and verified by the results obtained.     

Zur Altersstellung der Wiedener und Brandenberger Flußspatgänge (Südschwarzwald)

Zusammenfassung Eine tektonische Bearbeitung der Wiedener und Brandenberger Flußspatgänge ergab, daß diese sich in kilometerlangen, generell ± N-S-streichenden, an den Enden etwas gebogenen Störungen finden, die im engeren Sinne krummflächige Drehverwerfer sind, deren Ostschollen drehend nach Süden bewegt worden sind. Dieser Bewegungssinn läßt nicht mehr die bisherige Deutung dieser Gänge als Blattverschiebungen zu, die der varistischen Orogenese zuzuordnen sind. Die Flußspatgänge sind vielmehr an die Feldberg-Kuppel gebunden, die als Beule zumindest während der saxonischen, wenn nicht sogar während der tertiären Tektogenese entstanden ist. Für das daraus resultierende mesozoische oder tertiäre Alter auch der Flußspatgänge sprechen die neu interpretierten Untersuchungen an Schwefel-Isotopen des Bleiglanzes einiger Südschwarzwälder Erzgänge ebenfalls.

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A tectonical investigation of fluorspar veins in the region of Wieden and Brandenberg (Black Forest) shows that these veins are in faults having a length of several kilometers and striking approximately N-S. On their ends the faults are bowed. The eastern blocks of these curved rotation-faults are moved to the north. This direction of movement doesn't admit to interpret these veins as strike-slip dislocations, belonging to the Herzynian orogenesis. On the contrary, the fluorspar veins are bound to the Feldberg dome, which came into existence during the Saxonian orogenesis or even during the Tertiary. The resulting Mesozoic or Tertiary age of the fluorspar veins is confirmed also by investigations of sulfur isotopes of galena, made by several authors, on some ore veins in the southern part of the Black Forest.

     

Le Spèctre des Terres Rares de la Fluorine en Tant Que Marqueur des Propriétés du Milieu de Dépôt et des Interactions Entre Solutions Minéralisantes et Roches Sources. Exemple Pris dans le District de la Marche Occidentale (France)

Partitioning of lanthanides between solution and fluorspar is characterised by high partition coefficients in favor of fluorite, the coefficients growing slightly from La to Lu. On the example of the fluorite's district of the Western Marche France, we show how this property may be used as a geochemical criterion, to study the genesis of fluorspar. We find that two geochemical systems with different compositions and physicochemical properties have coexisted in the district. The first system deposited Chatenet and Charbonnière fluorite, the other one Rossignol fluorite. The chondrite normalised R. E. E. distribution of Rossignol fluorite shows a positive anomaly in europium, the origin of which is discussed. We propose that this anomaly (as well as the pattern of the various R. E. E. distributions analysed) are inherited from surrounding rocks by alteration processes rather than being the result of oxydoreduction phenomena. We suggest that, in general, coexistence of barite and of over-abundant europium fluorite is due to alteration of feldspars (or feldspar-rich rocks) which provides a possible source of barium.     

The application of Tb/Ca-Tb/La abundance ratios to problems of fluorspar genesis

A comprehensive review of the authors' and their co-workers' results on the fractionation of Rare Earth Elements (REE) during the crystallization and/or recrystallization of Fluorspar is given. The fractionation can be explained as the result of REE complexation in the ore forming solution and systematic changes in distribution coefficients of REE. It is shown that the Tb/Ca and Tb/La ratios are sufficient to characterize pegmatitic (pneumatolytic), hydrothermal and sedimentary fluorspar. This has been confirmed by numerous investigations on various types of deposits.     

Mineralogy of beneficiation problems involving fluorspar concentrates from carbonatite-related fluorspar deposits

Summary The World's three largest producers of fluorite from carbonatite-related fluorspar ore deposits are located at Okorusu (Namibia), Amba Dongar (India), and Mato Preto (Brazil). Beneficiation problems involving fluorite concentrates from those three deposits share similar characteristics that are directly related to the mineralogy and textures of the ores. The most important of these beneficiation problems involves their phosphorus, silica, and lime contents.Because the fluorite-depositing hydrothermal fluids were partly or largely derived from carbonatite sources, and carbonatites typically are rich in phosphorus, carbonatite-related fluorite deposits would be expected to be characterized by significant amounts of phosphorus mineral in the form of apatite. In the beneficiation products from those ore deposits, apatite occurs as free particles and especially as particles locked with fluorite. The presence of apatite in fluorite concentrates may contribute significant amounts of phosphorus, a deleterious constituent in fluorspar concentrates used in the steelmaking industry.Fluorite concentrates from some carbonatite-related fluorspar deposits are characterized by significant amounts of silica. The silica occurs especially in the form of quartz, potash feldspar, and sericite. Quartz occurs in both free particles and in particles where it is locked with fluorite. Quartz was deposited late in the paragenetic sequence and typically fills small vugs between the fluorite crystals. Potash feldspar formed during early potassic fenitization associated with the magmatic carbonatite emplacement. Potassic feldspar forms intricate intergrowths with fluorite that result in locked feldspar-fluorite particles in the fluorspar concentrates. The potash feldspar is intensely altered to sericite.Fluorite deposits that occur within a carbonatite host, such as those deposits at Amba Dongar and some deposits at Mato Preto, may have the grades of their fluorite concentrate diluted by the presence of calcite. The calcite commonly is present as binary locked calcite-fluorite particles in those fluorspar concentrates.Although the beneficiation problems concerning fluorite concentrates from carbonatite-related fluorspar deposits may be effectively studied by petrographic and ore microscopic techniques, cathodoluminescence microscopy has been found to be uniquely suited to rapid mineral recognition and the study of those minerals involved in fluorspar beneficiation problems.

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Mineralogische und aufbereitungstechnische Probleme von karbonatitischen Fluoritlagerstätten

Zusammenfassung Die weltgrößten Produzenten von Fluorit aus karbonatitischen Fluoritlagerstätten sind Okoruso (Namibia), Amba Dongar (Indien) und Mato Preto (Brasilien). Die Aufbereitungsprobleme der Fluoritkonzentrate aller drei Lagerstätten sind sehr ähnlich und stehen in direktem Zusammenhang mit der Mineralogie und Textur der Erze. Die wichtigsten Aufbereitungsprobleme sind durch die Phosphor-, Silizium- und Kalkge halte bedingt. Weil die hydrothermalen Fluide teilweise bzw. größtenteils aus phosphorreichen karbonatitischen Quellen stammen, ist zu erwarten, daß karbonatitische Fluoritlagerstätten beträchtliche Mengen an Phosphor in Form von Apatit führen. In den Aufbereitungsprodukten dieser Erze tritt Apatit sowohl in Form freier Partikel als auch verwachsen mit Fluorit auf. Die durch die Präsenz von Apatit verursachten erhöhten Phosphorgehalte sind bei Fluoritkonzentraten, die in der Stahlindustrie eingesetzt werden, störend.Fluoritkonzentrate einiger karbonatitischer Fluoritlagerstätten sind durch beträchtliche Siliziumgehalte charakterisiert, die durch Quarz, Alkalifeldspat und Serizit bedingt sind. Quarz tritt auf in Form freier Partikel, aber auch in engster Verwachsung mit Fluorit. Quarz wurde spät in der paragenetischen Abfolge ausgeschieden und füllttypischerweise kleine Hohlräume zwischen Fluoritkristallen. Alkalifeldspat bildete sich während der frühen potassischen Fenitisierung, die die Platznahme der Karbonatite begleitete. Alkalifeldspat ist engstens mit Fluorit verwachsen, was zu nicht trennbaren Feldspat — Fluoritpartikelen in den Konzentraten führt. Alkalifeldspat ist intensiv zu Serizit alteriert.Einigen Fluoritlagerstätten in karbonatitischen Wirtsgesteinen, wie etwa Amba Dongar und einige Lagerstätten bei Mato Preto, lassen eine Verdünnung des Fluoritkonzentrates durch die Anwesenheit von Calcit erkennen. Calcit kommt in den Konzentraten üblicherweise in Form binär verwachsener Calcit — Fluoritpartikel vor.Obwohl die Aufbereitungsprobleme von Fluoritkonzentraten aus karbonatitischen Fluoritlagerstätten sehr effektiv durch petrographische und erzmikroskopische Methoden studiert werden können, hat sich der Einsatz von Kathodenlumineszenz zur raschen Identifikation und für das Detailstudium der bei der Aufbereitung von Fluorit beteiligten Minerale bestens bewährt.

     

安徽铜陵狮子山铜矿田地球化学特征综述

安徽铜陵狮子山矿田是铜陵矿集区内储量最大的铜（金）矿田。矿田内矿床类型多样,成矿作用复杂,分布有东狮子山、西狮子山、大团山、老鸦岭、冬瓜山和花树坡等铜（金）矿床。这些矿床均围绕岩体产出,多数为隐伏矿,赋存于上石炭统一中三叠统的不同层位,在空间上具有明显的分带特征,由下向上依次为层控夕卡岩型、夕卡岩型和热液脉型矿床。其中...     

Mineralization of the South Pennines

The lead and fluorspar mining area of the Peak District, otherwise known as the South Pennine Orefield, includes much of Derbyshire and a small part of Staffordshire. There are some 2000 named mineral veins and related strata-bound deposits, containing galena, sphalerite, fluorite, baryte and calcite, hosted in Lower Carboniferous (Dinantian) limestones and dolomites. Small amounts of pyrite and chalcopyrite, and traces of many other minerals and hydrocarbons, are also present. Here we offer an explanation of how the minerals of the South Pennine Orefield were emplaced within the host rock.     

配加萤石、石膏复合矿化剂的立窑水泥熟料工艺岩石学的研究

配加萤石、石膏复合矿化剂的立窑水泥熟料可以分为4种类型:即葡萄状熟料、熔融烧结料、死烧块状料和还原料。这种水泥熟料都是由硅酸三钙、铁铝酸四钙、硅酸二钙、铝酸三钙以及少量的自由氧化钙组成的。在质量上熔融烧结熟料和死烧块状料优于葡萄状熟料,而还原料是所有热料中质量最差的。我们要改进水泥熟料的质量,必需降低还原料的数量。从工艺岩石学的观点来看,提高水泥熟料的质量,必需增加硅酸三钙、铁铝酸四钙的数量,减少自由氧化钙的数量,如果我们生产后述的水泥熟料,其质量一定是好的。     

Shigar valley gemstones,their chemical composition and origin,Skardu, Gilgit-Baltistan,Pakistan

A variety of gemstones is being mined in the Shigar valley, Skardu, Pakistan. These include beryl (goshenite and aquamarine), tourmaline (schorl), garnet (almandine–spessartine), apatite, topaz, fluorite, zoisite, clinozoisite, and axinite, mostly occurring in complex or zoned pegmatites and metamorphic rocks. These have been analyzed using electron probe micro-analyzer and X-ray diffractometer. The mineral chemistry of each gemstone is similar to its respective typical gemstone variety with homogenous chemical composition. Field and chemical characteristics suggest that beryl, tourmaline, garnet, apatite, topaz, and fluorite are occurring in zoned pegmatites which are largely formed by magmatic hydrothermal fluids in the cavities and vugs within the intermediate zone. However, zoisite, clinozoisite, and axinite may have a metamorphic and/or metasomatic origin.     

Sr and Nd isotope data from the fluorspar district of Asturias, northern Spain

The origin and age of the hydrothermal fluids related to the precipitation of fluorite, barite and calcite in the Villabona, La Collada and Berbes localities (Asturias fluorspar district, N Spain) have been evaluated from Sr and Nd radiogenic isotopes. Sr isotope data (⁸⁷Sr / ⁸⁶Sr = 0.7081 to 0.7096) are compatible with mixing between seawater and a more evolved groundwater that interacted with the basement. From Nd isotopes in fluorite, an isochron age of 185 ± 29 Ma (Lower Jurassic) was obtained, consistent with other hydrothermal events in the Iberian Peninsula and Europe. These constraints are essential to proceed with a quantitative model for the genesis of the mineralization that includes fluid and heat flow together with reactive transport of solutes.     

The plutonic igneous complex at Sorel Point,Jersey, Channel Islands: a high level multi-magma assemblage

Sorel Point lies on the north coast of Jersey, Channel Islands, and comprises a variety of lithologies within the compositional spectrum gabbro–diorite–granodiorite–granite. The rocks of the complex can be separated into four groups, each representing a separate intrusive episode. Each group consists of at least two lithologies which were present as coexisting magmas. The groups are separated by the time required for the preceding intrusive episode to crystallize completely. The rocks thus display a variety of contact relationships. Certain of the rocks present were produced by physical and chemical interactions between coexisting magmas. The rocks have calc-alkaline chemistry and were formed at high crustal levels during the latter stages of the Cadomian orogeny. The Sorel Point complex demonstrates the availability of a wide variety of magmas in a relatively condensed space and time and allows an insight into the formation of a constantly evolving subvolcanic magma chamber. © 1998 John Wiley & Sons, Ltd.     

(U–Th)/He dating of fluorite: application to the La Azul fluorspar deposit in the Taxco mining district, Mexico

The (U–Th)/He dating method was applied to fluorite of the La Azul fluorspar deposit, Taxco mining district, Mexico. Ages of ten U-rich (4–94 g/g) samples range from 30 to 33 Ma (mean 32±2 Ma, 1). This age range is interpreted as the time of primary fluorite precipitation and is close to the K/Ar age of sericite from a small fluorspar deposit (Los Tréboles) in the same area, and the K/Ar age of the nearby volcanic succession, which is thought to be the main source of fluorine in both deposits. This age is also in concordance with the very few published ages of epithermal deposits in southern Mexico. The dating of fluorite by other methods, particularly for young samples, is a difficult task. We believe that the (U–Th)/He method, which has been applied before to thermochronological studies of apatite, zircon, titanite and hematite, can be used as a tool for direct dating of fluorite with microgram per gram levels of uranium and thorium.Editorial handling: B. Lehmann     

湖南宜章界牌岭锡多金属矿床地质特征及成因浅析

界牌岭矿区出露的地层主要为石炭系,白垩系零星分布。石磴子组不纯灰岩化学性质活泼,同时地层中W,Sn,Be,Pb,Zn成矿元素含量高。界牌岭背斜控制了区内的总体构造格架,断裂构造很发育,其中近南北向断层是区内的控岩导矿构造,它所派生的次一级断裂控制着区内的锡铅锌矿体。区内仅出露燕山晚期的花岗斑岩。围岩蚀变主要有云母化、黄玉化、云英岩化、萤石化。锡铅锌矿体隐伏在80m标高以下,浅部及地表有厚大的萤石矿体。该矿床形成于燕山晚期,经历了从高温-中温-低温的成矿阶段。     

与侵入岩有关的脉型金矿:类型、构造岩浆背景及与造山带金矿的区别

一些金矿化类型表明它们与侵入岩有关。这些矿床产于侵入岩内部、附近或环绕单个侵入体 ,包括斑岩型、角砾岩型、矽卡岩型、交代型和脉型。其中由于脉型金矿多为中温热液金矿而使其在生成模式上最有争议 ,这就是由 Groves等 (1998)提出的造山带金矿。由于缺少任何与侵入岩有直接联系的流体证据 ,普遍认为造山带金矿是在挤压变形和区域变质作用期间或之后生成的。据矿脉矿物学及金属元素组合特征 ,可将与侵入岩有关的脉型金矿分为 5种类型及相应的金属元素组合 :Au Fe氧化物 Cu,Au CuMo Zn,Au As Pb Zn Cu,Au Te Pb Zn Cu和 Cu As BiSb类型。     

Remediation of floating,open water oil spills: Comparative efficacy of commercially available polypropylene sorbent booms

Several complex methods of remediation are applied to open water oil spills. Sorbing the liquid hydrocarbons with polypropylene booms is an effective and less complex means of treating such events. There are, however, a variety of commercially available booms which display different performances in sorbing different viscosity hydrocarbons. There is no acceptable A.S.T.M. protocol to evaluate these booms for performance efficiency in various weather and hydrocarbon viscosity scenarios. The current paper proposes such a protocol and evaluates the most commonly used sorbent products with the new test procedures. Nine specific performance criteria, based on actual field applications, are demonstrated.