Bystrite is redefined as a four-layer cancrinite-group mineral with the four-layer Losod-type framework and the end-member formula Na7Ca(Al6Si6O24)S52–Cl–. The mineral is known only at the Malo–Bystrinskoe gem lazurite deposit, Baikal Lake area, Siberia, Russia. The associated minerals are calcite, lazurite, sodalite, fluorapatite, phlogopite, diopside, dolomite and plagioclase. Bystrite is brittle, with the Mohs hardness of 5 and distinct cleavage on {10$\bar{1}$0}. The yellow colour of bystrite is due to the presence of S52– anions occurring in Losod (LOS) cages of the aluminosilicate framework with the ABAC stacking sequence. Measured and calculated density is, respectively, 2.43(1) and 2.412 g cm–3 for the holotype and 2.42(1) and 2.428 g cm–3 for the cotype sample. Bystrite is uniaxial (+), ɛ = 1.660(2) and ω = 1.584(2). The mineral was characterised by infrared and Raman spectra. The empirical formulae of the holotype and cotype samples are Na6.97K0.04Ca0.98(Si6.03Al5.97O24)(S52–)0.93[(SO42–)0.15Cl0.83] and Na6.75K0.04Ca1.11(Si6.09Al5.91O24)(S52–)1.04[(HS–)0.17Cl0.85], respectively. Bystrite is trigonal, space group P31c. The unit-cell parameters are: a = 12.8527(6) Å, c = 10.6907(5) Å, V = 1529.4(1) Å3 and Z = 2. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 4.821 (32) (102), 3.915 (38) (211), 3.712 (100) (300), 3.307 (50) (212), 2.782 (18) (400), 2.692 (22) (401), 2.673 (30) (004) and 2.468 (23) (402). Isomorphism and genesis of bystrite-type minerals is discussed. Bystrite and its K,HS-analogue sulfhydrylbystrite, Na5K2Ca(Al6Si6O24)S52–(HS)–, are indicators of highly reducing conditions.

Bystrite被重新定义为四层钙霞石族矿物，具有四层Losod型骨架，端元式为Na 7 Ca(Al 6 Si 6 O 24 )S 5 2– Cl –。这种矿物仅产于俄罗斯西伯利亚贝加尔湖地区的 Malo-Bystrinskoe 宝石青金矿矿床。伴生矿物有方解石、天青石、方钠石、氟磷灰石、金云母、透辉石、白云石和斜长石。Bystrite 很脆，莫氏硬度为 5，在 {10 $\bar{1}$ 0} 上有明显的解理。Bystrite 的黄色是由于铝硅酸盐框架 Losod (LOS) 笼中存在S 5 2–阴离子，ABAC堆叠顺序。测量和计算的正模样品密度分别为2.43(1)和2.412 g cm –3，共模样品密度为2.42(1)和2.428 g cm –3 。Bystrite 是单轴 (+) 的，ɛ = 1.660(2) 且 ω = 1.584(2)。通过红外和拉曼光谱对该矿物进行了表征。正型和共型样品的经验式为Na 6.97 K 0.04 Ca 0.98 (Si 6.03 Al 5.97 O 24 )(S 5 2– ) 0.93 [(SO 4 2– ) 0.15 Cl 0.83 ]和Na 6.75 K 0.04分别为Ca 1.11 (Si 6.09 Al 5.91 O 24 )(S 5 2– ) 1.04 [(HS – ) 0.17 Cl 0.85 ]。Bystrite是三角晶系，空间群P 31 c。晶胞参数为：a = 12.8527(6) Å、c = 10.6907(5) Å、V = 1529.4(1) Å 3和Z = 2。粉末 X 射线衍射图案的最强线 [ d , Å ( I , %) ( hkl)] 为：4.821 (32) (102)、3.915 (38) (211)、3.712 (100) (300)、3.307 (50) (212)、2.782 (18) (400)、2.692 (22) (401) )、2.673 (30) (004) 和 2.468 (23) (402)。讨论了菱镁矿类矿物的同象性和成因。Bystrite 及其 K,HS-类似物 sulfHydrylbystrite Na 5 K 2 Ca(Al 6 Si 6 O 24 )S 5 2– (HS) –是高度还原条件的指标。