The present study provides an example of the accurate identification of polytypes of trioctahedral 1:1 layered silicates from single-crystal X-ray diffraction data collected with the aid of a four-circle diffractometer equipped with an area detector. Single crystals of the mineral cronstedtite from the Nagybörzsöny gold ore deposit, northern Hungary, were studied. The chemical composition of some crystals was determined by electron probe microanalysis (EPMA). The precession-like images of the reciprocal space (RS) sections created by the diffractometer software and presented in the study were used to determine the OD (ordered-disordered) subfamilies (Bailey’s groups A, B, C, D) and particular polytypes. With one exception, all crystals studied belong to subfamily A. The rare polytype 1M, a = 5.51, b = 9.54, c = 7.33 Å, β = 104.5°, space group Cm is relatively abundant in this occurrence. Another polytype 3T, a = 5.51, c = 21.32 Å, space group P31 was also found. Both polytypes occur separately or in mixed, mostly 1M dominant crystals. Some 1M polytype crystals are twinned by order 3 reticular merohedry with a 120° rotation along the chex axis as the twin operation. A rare 1M+3T mixed crystal with 1M part twinned also contains a small amount of subfamily C. A possible presence of the most common 1T polytype of this subfamily cannot be confirmed because of overlap of the characteristic reflections with those of 3T. Several completely disordered crystals produced diffuse streaks instead of discrete characteristic reflections on the RS sections. The EPMA revealed Fe, Si, traces of Mg, Al, S, and Cl. One black crystal originally considered to be cronstedtite was identified as (111) twinned sphalerite. Some crystals of cronstedtite are covered partially by a honey-brown crust or small crystals of siderite.

中文翻译：

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来自匈牙利 NAGYBÖRZSÖNY 的 CRONSTEDTITE 多型

本研究提供了一个例子，说明从配备区域检测器的四圆衍射仪收集的单晶 X 射线衍射数据中准确识别三八面体 1:1 层状硅酸盐的多型。研究了来自匈牙利北部 Nagybörzsöny 金矿床的矿物 cronstedtite 的单晶。一些晶体的化学成分是通过电子探针微量分析（EPMA）确定的。由衍射仪软件创建并在研究中呈现的倒易空间 (RS) 截面的进动状图像用于确定 OD（有序-无序）亚族（Bailey 组 A、B、C、D）和特定的多型。除了一个例外，所有研究的晶体都属于亚家族 A。罕见的多型 1M，a = 5.51，b = 9.54，c = 7.33 Å，β = 104.5°，空间群 Cm 在这个事件中相对丰富。还发现了另一种多型体 3T，a = 5.51，c = 21.32 Å，空间群 P31。两种多型单独或混合出现，主要是 1M 主导晶体。一些 1M 多型晶体通过沿 chex 轴旋转 120° 的 3 阶网状多面体作为孪晶操作孪晶。具有 1M 部分孪晶的罕见 1M+3T 混晶也包含少量亚族 C。由于特征反射与 3T 的特征反射重叠，因此无法确认该亚族最常见的 1T 多型体的可能存在。几个完全无序的晶体在 RS 部分产生了漫射条纹，而不是离散的特征反射。EPMA 显示出 Fe、Si、痕量 Mg、Al、S 和 Cl。一种最初被认为是 cronstedtite 的黑色晶体被确定为 (111) 孪晶闪锌矿。一些 cronstedtite 晶体被蜜棕色外壳或菱铁矿小晶体部分覆盖。