Charmarite, Mn4Al2(OH)12CO3⋅3H2O, is a hydrotalcite supergroup member (or layered double hydroxide, LDH) with a previously unknown crystal structure and a Mn2+-analogue of quintinite (commonly erroneously reported as ‘2:1 hydrotalcite’). The single-crystal X-ray diffraction (XRD) data were obtained from the specimen from Mont Saint-Hilaire, Québec, Canada and are best processed in the space group P$\bar{3}$, a = 10.9630(4), c = 15.0732(5) Å and V = 1568.89(12) Å3. The crystal structure has been solved by direct methods and refined to R1 = 0.0750 for 3801 unique reflections with Fo > 2σ(Fo). The charmarite structure has long-range periodicity in the xy plane due to $2\sqrt 3$a’ × $2\sqrt 3$a’ scheme (or 11 × 11 Å) determined for LDHs for the first time (where a’ is a subcell parameter ≈ 3.2 Å). This periodicity is produced by the combination of two superstructures formed by: (1) Mn2+ and Al3+ ordering in the metal-hydroxide layers [Mn4Al2(OH)12]2+ according to the $\sqrt 3$a’ × $\sqrt 3$a’ pattern and (2) the (CO3)2– ordering according to the 2a’ × 2a’ pattern in the [CO3(H2O)3]2– interlayer sheet in order to avoid close contacts between adjacent carbonate groups. The $2\sqrt 3$a’ × $2\sqrt 3$a’ superstructure is an example of the adaptability of the components of the interlayer space to the charge distribution of the metal-hydroxyl layers. The Mn2+ and Al3+ cations have a large difference in size, which apparently leads to the considerable degree of their order as di- and trivalent cations resulting in a higher degree of statistical order of the interlayer components. Both powder and single-crystal XRD data show that the samples studied belong to the hexagonal branch of two-layer polytypes (2T or 2H) with d00n ≈ 7.57 Å. The chemical composition of the samples studied is close to the ideal formula. The Raman spectrum of charmarite is reported and the band assignment is provided.

Charmarite，Mn 4 Al 2 (OH) 12 CO 3 ⋅3H 2 O，是一种水滑石超族成员（或层状双氢氧化物，LDH），具有先前未知的晶体结构和五亚铁矿的 Mn 2+类似物（通常错误地报告为'2:1 水滑石'）。单晶 X 射线衍射 (XRD) 数据取自加拿大魁北克省 Mont Saint-Hilaire 的样品，并在空间群P $\bar{3}$中进行最佳处理，a = 10.9630(4)，c = 15.0732(5) Å 和V = 1568.89(12) Å 3。晶体结构已通过直接方法求解，并针对 3801 个独特反射细化至R 1 = 0.0750，且F o > 2σ( F o )。由于首次为 LDH 确定了 $2\sqrt 3$ a ' × $2\sqrt 3$ a ' 方案（或 11 × 11 Å）（其中a '是子单元参数 ≈ 3.2 Å)。这种周期性是由以下两种超结构组合产生的： (1)金属氢氧化物层中的Mn 2+和 Al 3+排序 [Mn 4 Al 2 (OH) 12 ] 2+根据$\sqrt 3$ a ' × $\sqrt 3$ a ' 模式和 (2) (CO 3 ) 2–根据[CO 3 (H 2 O) 3 ] 2–夹层片中的 2 a ' × 2 a ' 模式排序以避免相邻碳酸酯基团之间的紧密接触。 $ 2\sqrt 3$ a ' × $2\sqrt 3$ a ' 超结构是层间空间的组成部分对金属-羟基层的电荷分布适应性的一个例子。 Mn 2+和Al 3+阳离子的尺寸差异很大，这显然导致它们作为二价和三价阳离子的有序程度相当大，从而导致层间组分的统计有序程度较高。粉末和单晶 XRD 数据均表明所研究的样品属于d 00 n的双层多型体（2 T或 2 H）的六方晶系。约 7.57 埃。研究样品的化学成分接近理想配方。报告了红铜榴石的拉曼光谱并提供了谱带分配。