Brattforsite is an approved mineral (IMA2019-127), with ideal formula Mn₁₉(AsO₃)₁₂Cl₂. Associated minerals in the type specimen from the Brattfors mine, Nordmark (Värmland, Sweden) include jacobsite, alleghanyite, phlogopite, calcite and dolomite. Brattforsite, forming subhedral, mostly equant crystals up to 0.5 mm across, is orange to reddish-brown with a white streak, and translucent with a resinous to vitreous lustre. The fracture is uneven to subconchoidal, and no cleavage is observed. It is very weakly pleochroic in yellow, optically biaxial (–) with 2V = 44(5)° and has calculated mean refractive index of 1.981. Measured and calculated density values are 4.49(1) and 4.54(1) g·cm^− 3, respectively. Chemical analyses yields (in wt%): MgO 0.62, CaO 1.26, MnO 48.66, FeO 0.13, As₂O₃ 46.72, Cl 2.61, H₂O_calc 0.07, O ≡ Cl –0.59, sum 99.49, corresponding to the empirical formula (Mn_17.67Ca_0.58Mg_0.40Fe_0.05)_∑18.70As_12.17O_35.90Cl_1.90(OH)_0.20, based on 38 (O + Cl + OH) atoms per formula unit. The five strongest Bragg peaks in the powder X-ray diffraction pattern are [d (Å), I (%), (hkl)]: 2.843,100, (\( \overline{4} \)44); 2.828, 99, (444); 1.731, 32, (880); 2.448, 28, (800); 1.739, 25, (088). Brattforsite is monoclinic and pseudotetragonal, space group I2/a, with unit-cell parameters a = 19.5806(7), b = 19.5763(7), c = 19.7595(7) Å, β = 90.393(3)°, V = 7573.9(5) ų and Z = 8. The crystal structure was solved and refined to an R₁ index of 3.4 % for 7445 reflections [F_o > 4σ(F_o)]. Brattforsite has the same overall structural topology as magnussonite (i.e., the species can be considered as homeotypic), but with 12 independent tetrahedrally coordinated As sites and 21 Mn sites with varying (4–8) coordination. The Mn-centered polyhedra, bonded through edge- and face-sharing, give rise to a three-dimensional framework. The (AsO₃)³⁻ groups are bonded to this framework through corner- and edge-sharing. Spectroscopic measurements (optical absorption, Raman, FTIR) carried out support the interpretation of the compositional and structural data.

Brattforsite是一种经批准的矿物（IMA2019-127），具有理想的分子式Mn ₁₉（AsO ₃）₁₂ Cl ₂。诺德马克（瑞典韦姆兰）Brattfors矿的类型标本中的伴生矿物包括雅克贝石，Alleghanyite，金云母，方解石和白云石。Brattforsite形成近半面的晶体，最宽为0.5mm宽，为橙色至红棕色，带有白色条纹，半透明，具有树脂至玻璃光泽。骨折不均匀至亚贝壳状，也未观察到卵裂。它是黄色的弱双色性，光学双轴（–），2 V  = 44（5）°，计算出的平均折射率为1.981。测量和计算的密度值为4.49（1）和4.54（1）g·cm ^-3， 分别。化学分析产率（以重量％计）：MgO 0.62，CaO 1.26，MnO 48.66，FeO 0.13，As ₂ O ₃ 46.72，Cl 2.61，H ₂ O _calc 0.07，O≡Cl –0.59，总和99.49，对应于经验公式（Mn _17.67 Ca _0.58 Mg _0.40 Fe _0.05）_∑18.70 As _12.17 O _35.90 Cl _1.90（OH）_0.20（基于每个公式单位的38（O + Cl + OH）原子）。粉末X射线衍射图中五个最强的布拉格峰为[ d（Å），I（％），（hkl）]：2.843,100，（\（\ overline {4} \） 44）; 2.828，99，（444）; 1.731，32，（880）; 2.448，28，（800）; 1.739，25，（088）。Brattforsite是单斜晶和准四边形的，空间群I 2 / a，其晶胞参数a  = 19.5806（7），b  = 19.5763（7），c  = 19.7595（7）Å，β= 90.393（3）°，V  = 7573.9（5）³和ž  = 8的晶体结构解析和精到- [R ₁的3.4％指数为7445个反射[ ˚F _ø >4σ（˚F _Ò）]。Brattforsite具有与菱镁矿相同的整体结构拓扑（即，该物种可被视为同型），但具有12个独立的四面体配位的As位点和21个Mn位点（具有4-8的不同配位）。通过边缘和面共享将以锰为中心的多面体结合起来，形成了三维框架。（AsO ₃）³⁻基团通过边角共享和边共享而绑定到此框架。进行的光谱测量（光学吸收，拉曼光谱，FTIR）支持对成分和结构数据的解释。