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1.
桂林"鸡血红碧玉"是一种石英质玉石,颜色以鲜艳的红色与黑色为主,质地坚硬且耐磨。目前对该矿石的野外产状、地质背景、岩石结构和颜色成因等相关研究报道较少。野外勘察表明,桂林"鸡血红碧玉"矿床位于扬子板块与华夏板块交界处,产于广西北部龙胜地区新元古界丹洲群三门街组经含铁氧化物浸染的汽水热液浅变质砂岩中,其形成过程受到了新元古代-三叠纪数次大地构造与岩浆活动的影响,成因复杂。本文利用偏光显微镜和X射线衍射分析等手段,对桂林"鸡血红碧玉"的成分进行了深入研究,结果表明桂林"鸡血红碧玉"主要矿物组合为石英和赤铁矿,部分样品中含有白云石。石英呈现他形等粒结构和自形变斑晶结构;自形石英颗粒中可见加大边,指示后期经历过变质交代作用。赤铁矿在样品中呈现3种形式产出:1呈单晶形式产于石英颗粒的粒间与晶内;2呈点尘状包裹于石英颗粒中;3呈浸染状分布于石英颗粒间隙。赤铁矿中铁离子为红色致色原因。电子探针分析显示,浸染状和单晶赤铁矿中铁含量高达78.9%~85.6%;点尘状赤铁矿由于颗粒细小,难以精确分析其铁含量。结合石英和赤铁矿发育期次,认为"鸡血红碧玉"中不同形态的石英和赤铁矿的产出与区域地质演化背景相一致。 相似文献
2.
福建碧田铜金银矿床中的含银黄铜矿研究 总被引：2，自引：0，他引：2
福建碧田矿床是成因上与燕山晚期次火山岩有关的铜金银矿床。含银黄铜矿产于该矿床的金银矿石和银矿石中。含银黄铜矿呈粒度约０．００４－０．０７ｍｍ的他形粒状与银金矿，金银矿，自然银，辉银矿，黄铜矿，闪锌矿等共生，在空气中极易氧化。含银黄铜矿的银含量变化在１．０４５％－１４．２７３％之间，平均值为４．３７％。与黄铜矿比较，含银黄铜帮中硫含量变化不大，但铁与银有反消长关系。 相似文献
3.
河流泥沙粒径计法分析成果改正方法的实验研究 总被引：2，自引：0，他引：2
根据国家行业标准《河流泥沙颗粒分析规程》规定”粒径计分析成果，受群体沉降和扩散影响，应根据标样实验分析确定的方法进行校正“的要求，采集全国性河流１６个测站的悬沙样品，对粒径为０．０６２－０．５ｍｍ分析范围的粒径计法，以单颗沉降分析法为标准进行对比实验，据以确定粒径计法分析成果的改正方法，能充分满足颗分规程的质量检验要求。 相似文献
4.
5.
三趾马红粘土的粒度组成特征及其地质意义 总被引：10，自引：0，他引：10
黄河中游三趾马红粘土的粒度组成特征是以粉土（０．０５－０．００５ｍｍ）粒级为主，且粗粉土（０．０５—０．０１ｍｍ）粒级含量为所有粒级含量之冠，缺乏大于０．２５ｍｍ颗粒．主要粒级百分含量、粒度分布概率曲线显示出与黄土及现代风尘极为相似的面貌，表明三趾马红粘土为风力搬运的粉尘堆积． 相似文献
6.
本文对山西２５５个土壤样品（Ａ层）中的１２种微量元素含量与土壤颗粒（１．０～０．０１ｍｍ和０．０１～０．００１ｍｍ）含量分别进行相关分析，结果表明，上述绝大多数元素的含量与土壤颗粒含量之间呈显著相关性。同时将１２种元素的含量分别与上述两组土壤颗粒含量进行回归分析，得出各元素的推算模型。以此模型，即根据１．０～０．０１ｍｍ或０．０１～０．００１ｍｍ土壤颗粒含量，推算出土壤元素的含量。经验证，其推算结果与元素的实测值基本一致。 相似文献
7.
新矿物高台矿—铱的碲化物 总被引：2，自引：0，他引：2
高台矿产在纯橄榄岩体内的铬矿体中，在铬矿石及矿体邻近的砂矿中均可找到。常呈细脉状，等粒状聚集体，与硫铱矿、双峰矿紧密共生。矿物粒径０．０５－０．２ｍｍ，不透明，钢灰色，条痕为黑色，金属光泽。ＨＭ＝３。ＶＨＮ２０＝１１７ｋｇ／ｍｍ。无解理和断口。由于颗粒太小比重不能直接测定，计算得出矿物密度为１０．００ｇ／ｃｍ＾３。显微镜下矿物反射色为亮白微带蓝色调。无内反射。均质性。偶见淡黄、淡蓝偏光色。双反射与 相似文献
8.
9.
五台山康家沟金矿成矿地质特征 总被引：2，自引：0，他引：2
五台绿岩带柏枝岩组火山喷气岩由基－中酸性火山岩及其凝灰岩和含电气石，金云母的石英大理岩组成，其中赋存有金矿床。康家沟金矿区已发现金矿体８个，呈透镜状，长５０－２００ｍ，厚０．２８－４．４ｍ，延深１０－２００ｍ。矿石类型可分为赤铁矿－石英型和碳酸盐两种。／ 相似文献
10.
罗金玲 《华北地质矿产杂志》1998,13(2):202-203
太钢峨口铁矿矿石中的硫对钢铁质量有直接的影响研究其粒度与嵌布特征对合理的选择工艺流程有重要意义,硫化物的粒度分布在－１．１６４ｍｍ,主要粒级在－０．１４７６ｍｍ,矿物颗粒较小。从浅部到深部,从东往西其粒度逐渐变小。硫化物矿物的嵌布特征有四种：不等粒均均嵌布;不等粒事状嵌布;不等粒脉状嵌布;不等粒集结状嵌布。 相似文献
11.
The iron ores of the Gushan mine occur in the contact zone of a Mesozoic diorite intrusion and are composed primarily of hematite microcrystallites and chalcedony,The hematite microcrystallites have undergone post-mineralization recrystallization and coarsening with resultant formation of lath-shaped hematite porphyroblasts.Microscopic investigation reveals that recrystallization and coarsening of the hematite ores of the Gushan mine took place without the formation of new nuclei,due to the coalescence of the microcrystallites.The whole process could have begun with the mutual approach of the microcrystallites,followed by grain rotation to realize paralleism and ending by the welding of these grains to form optically homogeneous porphyroblastic hematite. 相似文献
12.
Banded iron formations of the Iron Ore Group (Archean greenstone belts) of Jharkhand-Orissa region, India host a good number
of large iron ore deposits (Fe wt %> 62). Iron ore mineralization of Gandhamardan hill is one of them where iron ores occur
in two stratigraphic horizons. One is strictly confined within banded iron formation (stratabound mineralization) with irregular
geometry, and show fracture filling and replacement vein-type mineralization along the fringes of hard massive ores of the
core. This type of mineralization is exposed along the western slope of the hill. Hard massive and laminated ores dominate
this mineralization. The other type occurs as low dipping sheet like body above banded iron formation and covered by laterites
forming the top of the hill. Flaky ores dominate this mineralization with formation of hard goethitic crust near the top.
Both the mineralizations contain mineralized banded iron formation corestones surrounded by hard massive or flaky iron ores.
Hard massive ores are entirely represented by martite-microplaty hematite mineralogy. Hard laminated ores contain microplaty
hematite and few martite grains representing early magnetites of the banded iron formation. Flaky ores are high porosity ores
produced by leaching of silica, martite and microplaty hematite. Hard goethitic ores are developed due to replacement of martite
and microplaty hematite or precipitation of goethite in the pore spaces. 相似文献
13.
智利Copiapó附近海岸东部边缘有一宽5km、长20km的铁氧化物铜金矿床带,包括Candelaria矿床和位于其北东方向3km处的Punta del Cobre矿集区的中小型矿床。初步估计,该成矿带的铜矿石资源量可达7×108~8×10~8t(含铜量1%)。矿石矿物主要为黄铜矿、黄铁矿、磁铁矿、赤铁矿。矿石产状为脉状、角砾状、细脉状等。含矿围岩主要为Punta del Cobre组的火山岩及火山碎屑岩。该矿带中大部分大型矿脉位于北西—北北西向高角度脆性断层与块状火山岩和火山碎屑岩接触带交汇处。Candelairia矿区主要发育黑云母-钾长石±钙角闪石±绿帘石蚀变矿物组合。在Punta del Cobr矿集区,矿床深部的矿石围岩蚀变情况与Candelairia地区一致,但是浅部的矿石赋存于黑云母-钾长石或钠长石-绿泥石±方解石蚀变带中。 相似文献
14.
Origin of Phenocrysts and Compositional Diversity in Pre-Mazama Rhyodacite Lavas, Crater Lake, Oregon 总被引：3，自引：3，他引：0
Phenocrysts in porphyritic volcanic rocks may originate in avariety of ways in addition to nucleation and growth in thematrix in which they are found. Porphyritic rhyodacite lavasthat underlie the eastern half of Mount Mazama, the High Cascadeandesite/dacite volcano that contains Crater Lake caldera, containevidence that bears on the general problem of phenocryst origin.Phenocrysts in these lavas apparently formed by crystallizationnear the margins of a magma chamber and were admixed into convectingmagma before eruption. About 20 km3 of pre-Mazama rhyodacite magma erupted during arelatively short period between400 and 500 ka; exposed pre-Mazamadacites are older and less voluminous. The rhyodacites formedas many as 40 lava domes and flows that can be assigned to threeeruptive groups on the basis of composition and phenocryst content.Phenocryst abundance decreases (from 32 to 8 vol.%) and SiO2content increases (from 68 to 73 wt.%) in the apparent orderof eruption. Phenocrysts (plagioclase, orthopyroxene, augite,and Fe-Ti oxides) are commonly fragmental or form polycrystallineaggregates with interstitial glass. Discrete phenocrysts withcomplete euhedral outlines are rare except for small elongatedcrystals. The abundance of discrete phenocrysts increases withthat of aggregates. The grain-size of minerals in the aggregatescovers the range of discrete phenocrysts (0.2–4.2 mm).Rim compositions of phenocrysts and the range of chemical zoningare almost uniform among the three rhyodacite groups, regardlessof whether crystals are discrete or in aggregates. However,a small fraction of phenocrysts, especially small elongatedcrystals, have different compositions: plagioclase with Fe-richcores and augite with Wo-poor cores, both of which are characteristicof crystals in undercooled andesite enclaves in the rhyodacites.The majority of phenocrysts were derived by disintegration ofpolycrystalline aggregates; rare, small phenocrysts crystallizedin andesitic magma similar to that represented by the andesiteenclaves. The modal and chemical compositions of the rhyodacites can beexplained by different degrees of admixing of crystals, representedby the aggregates, into magma having 4 vol.% ‘true’phenocrysts, mainly plagioclase. The aggregates may be partsof the rind formed by in situ crystallization near the walland roof of the magma chamber. The rind was disrupted duringor just before eruption, and pieces were variably disaggregatedand incorporated into erupting magma. The amount of rind incorporateddeclined during the sequence of eruptions. Owing to vesiculationof interstitial liquid and shearing during flow, crystals inthe aggregates were separated and became phenocrysts. Pre-Mazamarhyodacite was erupted dominantly as lava, as opposed to thecompositionally similar rhyodacite pumice of the Holocene caldera-formingeruption of Mount Mazama, apparently because its source chamberwas crystallizing inward rather than actively growing. 相似文献
15.
Precambrian iron ores of the Singhbhum-North Orissa region occur in eastern India as part of the Iron Ore Group (IOG) within the broad horse-shoe shaped synclinorium. More than 50% of Indian iron ore reserves occur in this region. Massive-hard, flaky-friable, blue dust and lateritic varieties of iron ores are the major ore types, associated with banded hematite, jasper and shales. These ores could have formed as a result of supergene enrichment through gradual but extensive removal of silica, alumina and phosphorus from banded iron formations and ferruginous shale. Attempts for optimal utilization of these resources led to various ore characterization studies using chemical analysis, ore and mineral petrography, XRD analysis, SEM and electron probe micro analysis (EPMA). The ore chemistry indicates that the massive hard ores and blue dust have high iron, low alumina and phosphorus contents. Because of high quality, these ores do not require any specialized beneficiation technique for up-gradation. However, flaky-friable, lateritised and goethitic ores are low in iron, high in alumina and phosphorus contents, requiring specific beneficiation techniques for up-gradation in quality. XRD, SEM and ore microscopic studies of massive hard ores indicate the presence of hematite and goethite, while flaky and lateritic ores show a higher concentration of goethite, kaolinite, gibbsite and hematite. EPMA studies show the presence of adsorbed phosphorous as fine dust in the hard ores. Sink and float studies reveal that most of the gangue minerals are not completely liberated in the case of goethitic and lateritic ores, even at finer fractions. 相似文献
16.
鞍钢弓长岭三矿区三种矿石类型的工艺矿物学研究 总被引：1，自引：0，他引：1
１ 矿石的物质组成１－１ 矿石的化学成分及矿物组成三矿区矿石的化学成分较简单,碱性系数很低,在０－０３％以下;矿石为高硅、贫铁,低ＣａＯ、ＭｇＯ、Ａｌ２Ｏ３,且有害杂质ＳＯ２、Ｐ２Ｏ５含量低于工业允许值（０－５％）的酸性矿石。随着矿石中ＦｅＯ含量的降低,ＣａＯ、ＭｇＯ、Ｋ２Ｏ含量有依次降低的趋势,Ｐ２Ｏ５及ＣＯ２也随ＦｅＯ降低而逐渐降低。矿石的矿物成分以赤铁矿、磁铁矿和石英为主,其它矿物成分很少,矿石类型不同,主要矿物含量也有差异。根据矿石的化学全分析及电子探针分析结果计算的矿石定量组成见表１。… 相似文献
17.
西北某矿石属低硫含磷的酸性低品位原生钒钛磁铁矿矿石,通过镜下鉴定、X射线衍射分析和扫描电镜分析等多种手段对原矿的化学成分、矿物组成及含量、矿物的产出形式、矿石的结构构造、主要目的矿物的嵌布粒度等进行了详细的工艺矿物学研究,查明矿石的工艺学特性.研究结果表明,该矿石具浸染状构造和交代构造,其中铁矿物主要是钛磁铁矿和赤铁矿,钛矿物包括钛铁矿、金红石和榍石等.钛磁铁矿和钛铁矿均属不均匀细粒—微细粒嵌布特征,在-400目占95%左右的磨矿细度条件下,通过选矿可获得铁精矿和钛精矿两种产品. 相似文献
18.
In felsitic parts of rhyolites from the Permian volcanism in Southwest Germany muscovite phenocrysts of magmatic origin were observed. They occur besides two other light-mica components of secondary formation. A Permian tuff from the SaarNahe area also contains this primary muscovite type.The muscovite, though mainly euhedral, is in some cases corroded by magmatic resorption. Combined with uncorroded, sharp-edged dihexahedric quartz, however, it proves that the acid host lavas during the Saalian tectonic phase rose and extruded in an unusually rapid manner. 相似文献
19.
Sedimentary beds of jasper (red hematitic chert) in the Ordovician Løkken ophiolite of Norway are closely associated with volcanogenic massive sulphide (VMS) deposits. The jaspers occur in the immediate hangingwall and laterally peripheral to the large Løkken (25–30 Mt) and small Høydal (0.1 Mt) VMS deposits, and are exposed discontinuously for several kilometres along strike. Massive or laminated types predominate; jasper-sulphide debris-flow deposits are also abundant near VMS deposits. The jaspers contain hematite-rich laminae showing soft-sediment deformation structures and microtextural evidence that record the presence of a colloidal precursor and an origin as gels. Early textures include: (1) straight or curved chains of hematitic filaments 3–10 µm in diameter and 20–100 µm long; (2) branching networks of 15–25 µm-thick, tubular structures surrounded by cryptocrystalline hematite and filled with quartz and euhedral hematite; (3) small (up to 10 µm) spherules composed of cryptocrystalline hematite and silica; and (4) up to 50 µm silica spherules with hematitic cores. The small filaments seem to have been deposited in varying proportions in the primary laminae, possibly together with hematitic and siliceous microspheroids. Diagenetic changes are represented by polygonal syneresis cracks, and the presence of cryptocrystalline (originally opaline) silica, chalcedony, quartz, carbonate and cryptocrystalline hematite and/or goethite forming botryoidal masses and spheroids <10 µm to 5 mm in diameter. Coarser euhedral grains of quartz, carbonate, and hematite are integral parts of these textures. Bleached, silica-rich jaspers preserve only small relics of fine-grained hematite-rich domains, and locally contain sparse pockets composed of coarse euhedral hematite±epidote. The jaspers are interpreted to record colloidal fallout from one or more hydrothermal plumes, followed by maturation (ageing) of an Si-Fe-oxyhydroxide gel, on and beneath the Ordovician sea floor. Small hematitic filaments in the jaspers reflect bacteria-catalysed oxidation of Fe 2+ within the plume. The larger tubular filaments resulted from either microbial activity or inorganic self-organized mineral growth of Fe-oxyhydroxide within the Si-Fe-oxyhydroxide gel after deposition on the sea floor, prior to more advanced maturation of the gel as represented by the spheroidal and botryoidal silica-hematite textures. Bleaching and hematite±epidote growth are interpreted to reflect heat and fluids generated during deposition of basaltic sheet flows on top of the gels. 相似文献
20.
Leonid V. Danyushevsky Michael R. Perfit Stephen M. Eggins Trevor J. Falloon 《Contributions to Mineralogy and Petrology》2003,144(5):619-637
Geochemical data from melt inclusions in olivine phenocrysts in a picritic basalt from the Siqueiros Transform Fault on the northern East Pacific Rise provide insights into the petrogenesis of mid-ocean ridge basalts (MORB). The fresh lava contains ~10% of olivine phenocrysts (Fo89.3-91.2) and rare, small (<1 mm) plagioclase phenocrysts with subhedral to irregular shapes with a range of compositions (An80-90, An57-63). Melt inclusions in olivine phenocrysts are glassy, generally rounded in shape and vary in size from a few to ~200 µm. Although most of the inclusions have compositions that are generally consistent with being representative of parental melts for the pillow-rim glasses, several inclusions are clearly different. One inclusion, which contains a euhedral grain of high-Al, low-Ti spinel, has a composition unlike any melt inclusions previously described from primitive phenocrysts in MORB. It has a very high Al2O3 (~20 wt%), very low TiO2 (~0.04 wt%) and Na2O (~1 wt%) contents, and a very high CaO/Na2O value (~14). The glass inclusion is strongly depleted in all incompatible elements (La =0.052 ppm; Yb =0.34; La/Sm(n) ~0.27), but it has large positive Sr and Eu anomalies (Sr/Sr* ~30; Eu/Eu* ~3) and a negative Zr anomaly. It also has low S (0.015 wt%) and relatively high Cl (180 ppm). We suggest that this unusual composition is a consequence of olivine trapping plagioclase in a hot, strongly plagioclase-undersaturated magma and subsequent reaction between plagioclase and the host olivine producing melt and residual spinel. Two other melt inclusions in a different olivine phenocryst have compositions that are generally intermediate between 'normal' inclusions and the aluminous inclusion, but have even higher CaO and Sr contents. They are also depleted in incompatible elements, but to a lesser degree than the aluminous inclusion, and have smaller Sr and Eu anomalies. Similar inclusions have also been described in high-Fo olivine phenocrysts from Iceland and northern Mid-Atlantic Ridge. We suggest that the compositions of these inclusions represent assimilation of gabbroic material into the hot primitive magma. The localised nature of this assimilation is consistent with it occurring within a crystal mush zone where the porosity is high as primitive magmas pass through earlier formed gabbroic 'cumulates'. In such an environment the contaminants are expected to have quite diverse compositions. Although the interaction of primitive melts with gabbroic material may not affect the compositions of erupted MORB melts on a large scale, this process may be important in some MORB suites and should be accounted for in petrogenetic models. Another important implication is that the observed variability in melt inclusion compositions in primitive MORB phenocrysts need not always to reflect processes occurring in the mantle. In particular, inferences on fractional melting processes based on geochemistry of ultra-depleted melt inclusions may not always be valid. 相似文献