A review of mineral associations and paragenetic groups of secondary minerals of the Jachymov (Joachimsthal) ore district
A review of mineral associations and paragenetic groups of secondary minerals of the Jachymov (Joachimsthal) ore district
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Jachymov (Joachimsthal) 矿区次生矿物的矿物组合和共生群综述
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
J. Hloušek
中科院分区：
文献类型：
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作者：
P. Ondruš;F. Veselovský;J. Hloušek
引言B）真辉铋矿钾霞石贝叶石紫镁矾钠镁矾在捷克共和国赠款机构支持的项目研究Jachymov矿区的次生矿物[299]的工作过程中，我们描述了207种次生矿物，并在许多情况下对其进行了更详细的表征，发现了30种新的自然相。这两个共生体的完整序列是罕见的。第一类共生矿物可分为两部分，包括以下几组矿物：辉铋矿、变辉钠长石、褐铁矿和辉铋矿、辉铋矿、钾霞石、真辉铋矿、铁辉铋矿。在这种情况下，原生矿物是自然铋，很少以3 mm以下的孤立颗粒出现，作为Geister脉石英中的骨架铋晶体的残留物。自然铋是由铋矿、偏铋矿和铋矿以微晶混合物的形式假晶化的。这些骨料为深灰色，并具有油脂至金刚光泽。铋矿也单独出现在天然铋晶体之后的洞穴的白色土状填充物中或作为灰尘涂层。这种共生的其他较年轻的矿物产于石英细脉的溶洞或沿着裂隙。鉴于这种复杂性，不仅要根据化学成分，而且要在共生组的框架内对矿物进行分类。八个不同的共生组的定义和讨论的次生矿物的形成条件。矿物学观察或报告的采样点周围环境的描述提供了关于矿物共生的信息。由于这方面的资料有时不完整，不可能确定所有矿物的共生位置。选择个别共生体的名称的目的是获得一个特定共生体的名称，这将充分不同于其他共生体。紫石英与变水砷铜矿共生。稀少的纤晶岩形成微黄色、半透明、光滑、光亮的球状体，沉积在溶洞壁上。灰黄色的土状到粉状铁铋矿和褐铁矿是共生体中最年轻的矿物。在本研究中，共生被理解为在单一成矿过程中同时或按顺序形成的矿物的常见产状。共生一词是用来表示没有成因关系的矿物的共同出现。由于所描述的所有矿物都是在风化过程中形成的，因此可以将共生一词理解为与共生相比，共同出现的矿物之间的关系通常较松散。自然铋作为原生矿物也有二次共生。其残留物长达0.5毫米，呈块状的流纹岩状，流纹岩可能也是原生矿物，呈深灰色，有蜡状光泽。它局部填充细脉达2厘米宽，并形成球形聚集体达1厘米宽，表面粗糙。一部分钠长石蚀变为辉铋矿和钾芒硝的块状灰褐色混合物。这些集合体以及细晶岩都被一层薄薄的黄色粉状铋矿所覆盖。尺寸约为100 μm的四方晶片中的贝叶石沉积在铋矿上，或与铋矿共生。铋的次生矿物共生
Introduction b) eulytite bismutite kettnerite beyerite pucherite namibite In the course of work on the project supported by the Grant Agency of the Czech Republic Study of secondary minerals in the Jachymov ore district [299] we have described and in many cases closer characterised 207 secondary mineral species and discovered 30 new natural phases. A complete sequence of these two paragenesis is rare. The first paragenesis can be considered in two parts, including the following groups of minerals: walpurgite metatorbernite limonite and bismite bismutite kettnerite eulytite bismutoferrite beyerite. The primary mineral in this case is native bismuth, occurring rarely as isolated grains to 3 mm, as remains of skeletal bismuth crystals in quartz of the Geister vein. The native bismuth was pseudomorphed by bismite, preisingerite, and bismutite in a microcrystalline mixture. These aggregates are dark grey in colour and have a greasy to adamantine lustre. Bismutite also occurs isolated in whitish earthy fill of vugs after crystals of native Bi or as a dusty coating. Other younger minerals of this paragenesis occur in vugs or along fractures of quartz veinlets. In view of this complexity, it proved necessary to characterise minerals not only on the basis of chemical compositions but also in the framework of paragenetic groups. Eight distinct paragenetic groups were defined and discussed in connection with conditions of formation of the secondary minerals. Mineralogical observations or reported descriptions of sampling sites surroundings provided information on mineral paragenesis. As this information was sometimes incomplete, it was not possible to characterise the paragenetic position of all minerals. The names of the individual paragenesis were chosen with the aim to obtain a designation for a particular paragenesis, which would be sufficiently distinct from other parageneses. Walpurgite occurs with metatorbernite. The scarce eulytite forms minute yellowish and translucent smooth and lustrous spheres, deposited on walls of the vugs. Earthy to powdery bismutoferrite of grey-yellow colour, and limonite are the youngest minerals of this paragenesis. In this study, paragenesis is understood as a common occurrence of minerals which formed at the same time, or in a sequence, during a single mineralization process. The term association is used to denote a common occurrence of minerals without genetic relations. Since all the minerals described formed during weathering processes, it is possible to understand the term association as indicating generally looser relations of jointly occurring minerals, in comparison to a paragenesis. Native bismuth served as the primary mineral also for a second paragenesis. Its remains up to 0.5 mm long are disseminated in massive eulytite, which was possibly in part also a primary mineral. This eulytite is dark grey, with a waxy lustre. It locally fills veinlets up to 2 cm wide and forms spherical aggregates up to 1 cm across, with a rough surface. A part of eulytite is altered to a massive grey-brown mixture of bismutite and kettnerite. These aggregates, as well as eulytite, are coated by a thin layer of yellow, powdery bismutite. Beyerite in tetragonal tablets of the order of 100 μm in size is deposited on, or intergrown with, bismutite. The paragenesis of secondary minerals of bismuth