A new mineral species, hydroxymcglassonite-(K), ideally KSr4Si8O20(OH)·8H2O, has been found in the Wessels mine, Kalahari Manganese Field, Northern Cape Province, South Africa. It is granular (<0.05 mm), associated with meieranite, sugilite, aegirine, pectolite, and yuzuxiangite. The mineral is colorless, transparent with a white streak and a vitreous luster. It is brittle and has a Mohs hardness of 4.5–5.0; cleavage is perfect on {001} and no parting or twinning was observed. The measured and calculated densities are 2.60(3) and 2.614 g/cm3, respectively. Optically, hydroxymcglassonite-(K) is uniaxial (+), with ω = 1.555(5), ε = 1.567(5) (white light), and absorption O > E. Hydroxymcglassonite-(K) is insoluble in water or hydrochloric acid. An electron microprobe analysis yielded an empirical formula (based on 13 non-H cations pfu) K1.01(Sr2.99Ca1.03)Σ4.02Si7.99O20(OH)·8H2O, which can be simplified to K(Sr,Ca)4Si8O20(OH)·8H2O.Hydroxymcglassonite-(K) is tetragonal with space group P4/mnc and unit-cell parameters a = 9.0792(2), c = 16.1551(9) Å, V = 1331.70(9) Å3, and Z = 2. It is isostructural with hydroxyapophyllite-(K), KCa4Si8O20(OH)·8H2O, with Sr substituting for Ca. The crystal structure of hydroxy-mcglassonite-(K) is characterized by SiO4 tetrahedra sharing corners to form (Si8O20)8– sheets parallel to (001), which are connected by the K and B (= Sr + Ca) cations, as well as hydrogen bonding. The K cation is coordinated by eight H2O groups, and the average K–O distance of 2.941(3) Å is shorter than that of 2.950(3)–2.975(3) Å in hydroxyapophyllite-(K) or fluorapophyllite-(K). The B cation is sevenfold-coordinated (4O + 2H2O + OH), and the average B-O distance of 2.522(3) Å is noticeably longer than that of 2.422–2.435 Å in hydroxyapophyllite-(K) or fluorapophyllite-(K). The Raman spectra of hydroxymcglassonite-(K) and hydroxyapophyllite-(K) are very comparable, especially in the O-H stretching region. The discovery of hydroxymcglassonite-(K), the first Sr-bearing mineral of the apophyllite group, implies that more Sr-bearing members of the group may be found in nature or synthesized in laboratories, but the possibility for an incomplete solid solution between hydroxyapophyllite-(K) and hydroxymcglassonite-(K), due to the size difference between Sr2+ and Ca2+, cannot be ruled out.

中文翻译：

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羟基玻璃石-(K), KSr4Si8O20(OH)·8H2O, 鱼眼石组的第一个含 Sr 成员, 来自南非卡拉哈里锰田 Wessels 矿

在南非北开普省卡拉哈里锰矿区的 Wessels 矿中发现了一种新的矿物种类，羟基微晶石-(K)，理想情况下为 KSr4Si8O20(OH)·8H2O。呈颗粒状（<0.05 mm），伴生于梅兰石、苏吉石、云石、硅藻土和玉足香石。矿物无色透明，有白色条纹，有玻璃光泽。它很脆，莫氏硬度为 4.5-5.0；{001} 上的分裂是完美的，没有观察到分离或孪晶。测量和计算的密度分别为 2.60(3) 和 2.614 g/cm3。光学上，羟基玻璃石-(K) 是单轴的 (+)，ω = 1.555(5)，ε = 1.567(5)（白光），吸收 O > E。羟基玻璃石-(K) 不溶于水或盐酸. 电子探针分析得出经验公式（基于 13 个非 H 阳离子 pfu）K1。01(Sr2.99Ca1.03)Σ4.02Si7.99O20(OH)·8H2O，可简化为K(Sr,Ca)4Si8O20(OH)·8H2O。Hydroxymcglassonite-(K)为四方，空间群为P4/mnc和晶胞参数 a = 9.0792(2), c = 16.1551(9) Å, V = 1331.70(9) Å3, 和 Z = 2。它与羟基鱼眼石-(K)、KCa4Si8O20(OH)·8H2O 同构，用 Sr 代替 Ca。羟基-mcglassonite-(K) 的晶体结构的特征是 SiO4 四面体共用角形成平行于 (001) 的 (Si8O20)8– 片层，它们也由 K 和 B (= Sr + Ca) 阳离子连接作为氢键。K 阳离子由 8 个 H2O 基团配位，2.941(3) Å 的平均 K-O 距离短于羟基鱼眼石-(K) 或 fluorapophyllite-(K) 中的 2.950(3)–2.975(3) Å . B 阳离子是七倍配位的 (4O + 2H2O + OH)，平均 BO 距离为 2。522(3) Å 明显长于 2.422–2.435 Å 在羟基鱼腥藻石-(K) 或氟鱼腥藻石-(K) 中的长度。羟基微晶玻璃石-(K) 和羟基鱼眼石-(K) 的拉曼光谱非常具有可比性，尤其是在 OH 拉伸区域。羟基麦玻璃石-(K)是鱼雀石族中第一个含Sr矿物的发现，意味着该族中更多的含Sr成员可能在自然界中发现或在实验室中合成，但羟基鱼雀石之间可能存在不完全固溶体-(K) 和羟基微晶玻璃石-(K)，由于 Sr2+ 和 Ca2+ 的尺寸差异，不能排除。