Abstract—This paper describes the first Na-dominant member of the beryl group, named avdeevite. The sample, which became its holotype, was found in a granitic pegmatite at the Kat Chay (Palelni) mine near the town of Momeik, Kyaukme district, Shan State, Myanmar. Both avdeevite and beryl form sheaflike aggregates up to 4 cm, consisting of hexagonal prismatic crystals up to 1 сm long and up to 1 mm thick. These crystals consist of epitactically intergrown avdeevite (core) and beryl (rim). The new mineral is pink and transparent with vitreous luster. The Mohs hardness is 8, D_meas = 2.89(2) and D_calc = 2.875 g/cm³. Avdeevite is optically uniaxial (–), ω = 1.601(2), ε = 1.594(2); in transmitted light, the mineral is colorless and nonpleochroic. The chemical composition of holotype (electron microprobe, Be, Li and H by ion microprobe) is, wt %: 61.06 SiO₂, 17.40 Al₂O₃, 8.58 BeO, 1.77 Na₂O, 0.09 K₂O, 6.44 Cs₂O, 1.38 Rb₂O, 2.51 Li₂O, 0.42 H₂O; the total is 99.63. The empirical formula is (Na_0.34Cs_0.27H₂O_0.14Rb_0.09K_0.01)_Σ0.85(Be_2.04Li_1.00)_Σ3.04Al_2.03Si_6.03O₁₈. Taking into account the previously published data for samples with compositions corresponding to avdeevite, the simplified formula of this mineral may be most correctly written as: [(Na,R')_0.5–1(H₂O)_y]{(Be,Li)₃(Al,M²⁺)₂Si₆O₁₈}, y ≤ 1, R' = Cs, Rb, K, Ca, M²⁺ = Fe, Mg, Mn. The crystal structure has been studied by single-crystal X-ray diffraction, R = 0.0322. The mineral is hexagonal, space group P6/mcc. The unit-cell parameters are: a = 9.2287(4) Å, c = 9.2610(3) Å, V = 683.07(5) ų, and Z = 2. The strongest reflections of the XRD pattern are [d_meas, Å (I, %) (hkl)]: 7.96 (82) (100), 4.60 (31) (002), 3.99 (102) (200), 3.26 (100) (112), 3.02 (37) (202) (210), 2.866 (84) (211), 1.742 (19) (304) (410). Avdeevite belongs to the beryl structural type. This mineral differs from beryl sensu stricto in that the total large cations in channels exceeds 0.5 apfu and Na dominates among these cations. Avdeevite is named after Ivan Vasil’evich Avdeev (1818–1865), the renowned Russian chemist and mining engineer, who led the major studies of natural and synthetic beryllium compounds. The paper also contains data on the history of Na-bearing beryls including previously described samples, which correspond to avdeevite.

摘要——本文描述了绿柱石族中第一个以 Na 为主的成员，名为 avdeevite。在缅甸掸邦 Kyaukme 区 Momeik 镇附近的 Kat Chay (Palelni) 矿的花岗伟晶岩中发现了成为其正模标本的样品。avdeevite 和绿柱石均形成长达 4 厘米的束状聚集体，由长达 1 厘米、厚达 1 毫米的六角棱柱晶体组成。这些晶体由外延共生的 avdeevite（核心）和绿柱石（边缘）组成。新矿物呈粉红色透明，有玻璃光泽。莫氏硬度为 8，D _meas = 2.89(2) 和D _calc = 2.875 g/cm ³. Avdeevite 是光学单轴 (–)，ω = 1.601(2)，ε = 1.594(2)；在透射光下，该矿物是无色且非多色性的。全息图（电子探针、Be、Li、H离子探针）的化学成分，wt%：61.06 SiO ₂、17.40 Al ₂ O ₃、8.58 BeO、1.77 Na ₂ O、0.09 K ₂ O、6.44 Cs ₂ O , 1.38 Rb ₂ O, 2.51 Li ₂ O, 0.42 H ₂ O; 总数为 99.63。经验公式为 (Na _0.34 Cs _0.27 H ₂ O _0.14 Rb _0.09 K _0.01 ) _Σ0.85 (Be_2.04 Li _1.00 ) _Σ3.04 Al _2.03 Si _6.03 O ₁₈ . 考虑到先前公布的成分对应于 avdeevite 的样品的数据，这种矿物的简化公式可能最正确地写为： [(Na, R ') _0.5–1 (H ₂ O) _y ]{(Be,Li ) ₃ (Al, M ²⁺ ) ₂ Si ₆ O ₁₈ }, y ≤ 1, R ' = Cs, Rb, K, Ca, M ²⁺=铁、镁、锰。通过单晶X射线衍射研究了晶体结构，R = 0.0322。矿物是六方的，空间群P 6 /mcc。晶胞参数为：a = 9.2287(4) Å, c = 9.2610(3) Å, V = 683.07(5) Å ³和Z = 2。XRD 图案的最强反射是 [ d _meas , Å (我, %) (港元)]: 7.96 (82) (100), 4.60 (31) (002), 3.99 (102) (200), 3.26 (100) (112), 3.02 (37) (202) (210), 2.866 (84) (211)、1.742 (19) (304) (410)。Avdeevite 属于绿柱石结构类型。这种矿物与狭义绿柱石的不同之处在于通道中的总大阳离子超过 0.5 apfu，而 Na 在这些阳离子中占主导地位。Avdeevite 以俄罗斯著名化学家和采矿工程师 Ivan Vasil'evich Avdeev (1818–1865) 的名字命名，他领导了对天然和合成铍化合物的主要研究。该论文还包含有关含钠绿柱石的历史数据，包括先前描述的样品，这些样品对应于 avdeevite。