Data for: Mineralogy and genesis of rare Al-phosphate minerals in weathered itabirite and iron ore from the Quadrilátero Ferrífero, Minas Gerais, Brazil

The files contain powder and micro XRD, and microprobe analyses for rare, secondary phosphates (augelite, senegalite, turquoise) formed by chemical weathering of carbonate veins in itabirite and iron ore on the Quadrilatero Ferrífero, Minas Gerais, Brazil.
To obtain samples as pure as possible of the different phosphate minerals for XRD analyses, small fragments (~1.0 cm long) were crushed below 1mm and ultrasonic washed with distilled water. Two different materials were examined: (i) a thin (~2 mm) film of phosphate minerals that line and cement P-bearing concretions (Fig. 2i and g), (ii) a brownish, very porous material, containing phosphate minerals that occur underneath the thin film (Fig. 2f and h). Fragments below 1 mm of both materials were handpicked using a binocular microscope, trying to avoid contamination with hematite.
In addition to powder XRD, 35 in situ micro-XRD analyses were performed to identify secondary phosphate phases in polished thin sections. XRD data were collected using a Rigaku SmartLab XRD equipped with a 9 kW Cu rotating anode source, operated at 45 kV and 200 mA. A parabolic multilayer X-Ray mirror parallel-optics system with a polycapillary optics attachment produced a high-intensity point focus on the sample. A 0.2 collimator was used to reduce the beam diameter to 200 µm. Diffraction patterns were recorded by continuous scans from 5 to 70° 2Ɵ, with a step size of 0.02° at a scan rate of 2° per minute. The resulting patterns for both powder and microdiffraction were imported into Diffrac EVA version 4.2, where phases were identified using the PDF-4 2019 ICDD database.
Quantitative chemical analyses of the major and minor elements of secondary phosphates were carried out on selected samples using electron microprobe in wavelength dispersive mode (EMPA-WDS) using a JEOL JXA-8200, at the CMM-UQ. Operating conditions were 15 kV, 15 nA and beam diameter of 10 μm. Natural and synthetic standards used were: apatite for P (TAP; Kα), wollastonite for Ca (PETJ; Kα) and Si (TAP; Kα), spinel for Mg (TAP; Kα) and Al (TAP; Kα), Fe2O3 for Fe (LIF; Kα), Cu metal for Cu (LIF; Kα), ZnO for Zn (LIF; Kα), spessartite for Mn (LIF; Kα), Bananb02 for Ba (PET; lα), Bi metal for Bi (PETJ; mα), SrTiO3 for Sr (TAP, lα) and InAs for As (TAP, lα). H2O was calculated by imposing the closure to 100 wt. %.

该数据集包含由巴西米纳斯热里斯州Quadrilatero Ferrífero地区的碳酸脉化学风化形成的稀有次生磷酸盐（如方铅矿、塞内加尔石、青金石）的粉末和微X射线衍射，以及微探针分析。为获取尽可能纯净的不同磷酸盐矿物的样品以进行X射线衍射分析，取长约1.0厘米的小碎片，将其粉碎至1毫米以下，并使用蒸馏水进行超声波清洗。考察了两种不同的材料：（i）磷灰石矿物薄层（约2毫米厚），该层沿P含量胶结体边缘和胶结，（图2i和g），（ii）一种棕色、多孔的材料，其中含有位于薄层之下的磷酸盐矿物（图2f和h）。使用双目显微镜手工挑选两种材料中1毫米以下的碎片，力求避免赤铁矿的污染。

此外，还进行了35次原位微X射线衍射分析，以识别抛光薄片中的次生磷酸盐相。使用配备9千瓦Cu旋转阳极源的Rigaku SmartLab X射线衍射仪收集X射线数据，工作电压为45千伏，电流为200毫安。使用抛物面多层X射线镜平行光学系统，配备多毛细管光学附件，在样品上产生高强度点聚焦。使用0.2毫米的准直器将光束直径减小至200微米。衍射模式通过从5°至70°2θ的连续扫描记录，扫描速率为每分钟2°，步长为0.02°。粉末和微衍射的衍射模式被导入Diffrac EVA版本4.2，其中使用PDF-4 2019 ICDD数据库进行相识别。

使用波长色散模式下的电子探针（EMPA-WDS）对选定的次生磷酸盐的主要和微量元素进行定量化学分析，使用JEOL JXA-8200在CMM-UQ进行。操作条件为15千伏、15纳安和10微米的光束直径。使用的天然和合成标准分别为：磷酸钙（TAP；Kα）用于P，透辉石（PETJ；Kα）用于Ca和Si，尖晶石（TAP；Kα）用于Mg和Al，三氧化二铁（LIF；Kα）用于Fe，铜金属（LIF；Kα）用于Cu，氧化锌（LIF；Kα）用于Zn，尖晶石（LIF；Kα）用于Mn，Bananb02（PET；lα）用于Ba，铋金属（PETJ；mα）用于Bi，锶钛氧化物（TAP，lα）用于Sr，InAs（TAP，lα）用于As。水含量通过将质量百分比封闭至100 wt. %进行计算。