Hydroxylpyromorphite, Pb5(PO4)3(OH), has been documented in the literature as a synthetic and naturally occurring phase for some time but has not previously been formally described as a mineral. It is fully described here for the first time using crystals collected underground in the Copps mine, Gogebic County, Michigan. Hydroxylpyromorphite occurs as aggregates of randomly oriented hexagonal prisms, primarily between about 20–35 μm in length and 6–10 μm in diameter. The mineral is colorless and translucent with vitreous luster and white streak. The Mohs hardness is ~3½–4; the tenacity is brittle, the fracture is irregular, and indistinct cleavage was observed on {001}. Electron microprobe analyses provided the empirical formula Pb4.97(PO4)3(OH0.69F0.33Cl0.06)Σ1.08. The calculated density using the measured composition is 7.32 g/cm3. Powder X-ray diffraction data for the type material is compared to data previously reported for hydroxylpyromorphite from the talc mine at Rabenwald, Austria, and from Whytes Cleuch, Wanlockhead, Scotland. Hydroxylpyromorphite is hexagonal, P63/m, at 100 K, a = 9.7872(14), c = 7.3070(10) Å, V = 606.16(19) Å3, and Z = 2. The structure [R1 = 0.0181 for 494 F>4σ(F) reflections] reveals that hydroxylpyromorphite adopts a column anion arrangement distinct from other members of the apatite supergroup due to the presence of fluorine and steric constraints imposed by stereoactive lone-pair electrons of Pb2+ cations. The F– anion sites are displaced slightly from hydroxyl oxygen anions, which allows for stronger hydrogen-bonding interactions that may in turn stabilize the observed column-anion arrangement and overall structure. Our modern characterization of hydroxylpyromorphite provides deeper understanding to a mineral useful for remediation of lead-contaminated water.

中文翻译：

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羟基焦吗啉，一种对铅修复很重要的矿物：现代描述和表征

羟基焦吗啉，Pb5(PO4)3(OH)，一段时间以来一直在文献中被记录为合成和天然存在的相，但以前没有被正式描述为矿物。此处首次使用在密歇根州 Gogebic 县 Copps 矿井地下收集的晶体对其进行了全面描述。羟基焦吗啉以随机取向的六边形棱柱的聚集体形式出现，主要长约 20-35 微米，直径约 6-10 微米。矿物无色半透明，有玻璃光泽和白色条纹。莫氏硬度为 ~3½–4；韧脆，断口不规则，在{001}上观察到不明显的解理。电子探针分析提供了经验式 Pb4.97(PO4)3(OH0.69F0.33Cl0.06)Σ1.08。使用测得的组合物计算出的密度为 7.32 g/cm3。将该类型材料的粉末 X 射线衍射数据与先前报道的来自奥地利 Rabenwald 滑石矿和来自苏格兰 Wanlockhead 的 Whytes Cleuch 的羟基焦吗啉的数据进行比较。羟基焦吗啉为六方晶系，P63/m，在 100 K，a = 9.7872(14)，c = 7.3070(10) Å，V = 606.16(19) Å3，Z = 2。结构 [R1 = 0.0181 for 494 F> 4σ(F) 反射]表明，由于 Pb2+ 阳离子的立体活性孤对电子施加的氟和空间约束的存在，羟基焦吗啉采用与磷灰石超群其他成员不同的柱状阴离子排列。F-阴离子位点从羟基氧阴离子中略微移位，这允许更强的氢键相互作用，从而可以稳定观察到的柱-阴离子排列和整体结构。