Abstract

Dalnegorskite, a new pyroxenoid with the crystal chemical formula Ca₂Ca₂MnCa(Si₃O₉)₂ and simplified formula Ca₅Mn(Si₃O₉)₂, is a rock-forming mineral in the B-bearing calcic skarns in the Dalnegorsk borosilicate deposit (Dalnegorsk, Primorsky Krai, Russia). It belongs to the bustamite structural type and forms a continuous solid-solution series with isostructural ferrobustamite Ca₂Ca₂FeCa[Si₃O₉]₂. These pyroxenoids form beige, pinkish white and milky white radiated aggregates typically consisting of split thin acicular to fiber-like individuals and are associated with hedenbergite, datolite, andradite, galena, sphalerite, and pyrrhotite. D_meas. = 3.02(2), D_calc. = 3.035 g cm^–3. Dalnegorskite is biaxial negative, α = 1.640 (3), β = 1.647 (3), γ = 1.650 (3)°, 2V_meas. = 75(10)°. The average chemical composition of the holotype (electron microprobe data) is: 0.23 MgO, 40.02 CaO, 5.02 MnO, 3.64 FeO, 50.65 SiO₂, total 99.56 wt %. The empirical formula calculated for 18 O atoms is Ca_5.03Mn_0.51Fe_0.36Mg_0.04Si_6.01O₁₈. The crystal structure of the new mineral was obtained from X-ray diffraction data using the Rietveld method, R_p= 0.0345, R_wp = 0.0444, R₁ = 0.0790, and wR₂ = 0.0802. Dalnegorskite is triclinic, P-1, a = 7.2588(11), b = 7.8574(15), c = 7.8765(6) Å, α = 88.550(15), β = 62.582(15), γ = 76.621(6)°, V = 386.23(11) ų, and Z = 1. Dalnegorskite is distinct from the related mineral wollastonite in the infrared spectrum. The wave numbers of the maxima of strong bands in the Si–O stretching vibration region in the IR spectrum of dalnegorskite are (cm^–1): 905, 937, 1025, and 1070. The holotypic specimen of dalnegorskite is kept in the collection of the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, Russia (no. 96201).

中文翻译：

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Dalnegorskite Ca 5 Mn（Si 3 O 9）2，一种新的类辉石结构的约旦石，一种在俄罗斯滨海边疆区Dalnegorsk硼硅酸盐矿床中钙矽卡岩的成岩矿物

摘要

Dalnegorskite是一种新型的吡咯烷酮，具有化学式Ca ₂ Ca ₂ MnCa（Si ₃ O ₉）₂和简化式Ca ₅ Mn（Si ₃ O ₉）₂，是B型含钙矽卡岩中的一种成岩矿物。 Dalnegorsk硼硅酸盐矿床（Dalnegorsk，俄罗斯滨海边疆区）。它属于白云母结构类型，与同构的铁矾石Ca ₂ Ca ₂ FeCa [Si ₃ O ₉ ] ₂形成连续的固溶体系列。。这些吡喃类化合物形成米色，粉红色白色和乳白色辐射状的聚集体，通常由针状至纤维状个体的分裂的稀薄组成，并与变长石，闪锌矿和堇青石，方铅矿，闪锌矿和黄铁矿相关。D_测量。= 3.02（2），D_计算。= 3.035克厘米^–3。斜方锰矿是双轴负性的，α= 1.640（3），β= 1.647（3），γ= 1.650（3）°，2 V_测量值。= 75（10）°。整型的平均化学组成（电子探针数据）为：0.23 MgO，40.02 CaO，5.02 MnO，3.64 FeO，50.65 SiO ₂，总计为99.56 wt％。计算出的18个O原子的经验公式为Ca _5.03 Mn _0.51 Fe _0.36镁_0.04 Si _6.01 O ₁₈。使用Rietveld方法从X射线衍射数据获得新矿物的晶体结构，R _p = 0.0345，R _wp  = 0.0444，R ₁ = 0.0790和wR ₂ = 0.0802。钠云母为三斜晶系，P -1，a = 7.2588（11），b = 7.8574（15），c = 7.8765（6）Å，α= 88.550（15），β= 62.582（15），γ= 76.621（6） °，V = 386.23（11）一种³，和ž= 1。钠云母与红外光谱中的相关矿物硅灰石截然不同。钠云母红外光谱中Si–O拉伸振动区域中强带的最大值的波数为（cm – ¹）：905、937、1025和1070。俄罗斯科学院Fersman矿物学博物馆，俄罗斯莫斯科（编号96201）。