Oxy-dravite, ideally Na(Al2Mg)(Al5Mg)(Si6O18)(BO3)3(OH)3(O), was found in a composition near its ideal end-member at the Beluga occurrence, Nunavut territory, Canada. It occurs in retrograde albite–muscovite–corundum–calcite domains in a calc-silicate rock. This uncommon oxy-dravite occurs as dark brown, equant to short-prismatic, idiomorphic crystals with vitreous lustre and up to ca. 4 × 3 cm in size. The oxy-dravite is optically uniaxial (–), with ω = 1.6453(5) and ɛ = 1.6074(18); its calculated density is 3.069 g.cm–3 with a compatibility index of 0.016. The Beluga oxy-dravite has trigonal symmetry, space group R3m with a = 15.9121(2) Å, c = 7.1788(10) Å, V = 1574.12(5) Å3 and Z = 3. The crystal structure was refined to R1 = 1.45 using 1613 unique reflections. The empirical crystal-chemical formula is X(Na0.88Ca0.08□0.03K0.01)Y(Al1.49Mg1.31Fe0.15Ti0.04Zn0.01)Z(Al5.42Mg0.58)T(Si5.84Al0.16O18)B(BO3)3V(OH2.95O0.05)W(O0.84OH0.01F0.15).

Oxy-dravite in nature commonly occurs in a solid solution with foitite, schorl and oxy-schorl. At the Beluga occurrence, its minor contents of Al, vacancy [□], and Ca are most likely compensated by (□Al)(NaR2+)–1 and (CaMg)(NaAl)–1 exchanges of the oxy-magnesio-foitite and magnesio-lucchesiite components. The Beluga occurrence of oxy-dravite is characterised by an Mg-rich environment related to a metamorphic overprint of the original sedimentary sequence. This sequence of marine dolomitic argillaceous marl was influenced by (B,Cl)-rich fluids, probably proximally-derived from mineral breakdown reactions in the calc-silicate during the retrograde stage of metamorphism. The locality is a rare example of a tourmaline + corundum assemblage.

氧镁镁石，理想情况下为 Na(Al 2 Mg)(Al 5 Mg)(Si 6 O 18 )(BO 3 ) 3 (OH) 3 (O)，在 Beluga 矿点发现其成分接近其理想端元，努纳武特地区，加拿大。它发生在钙硅酸盐岩石的逆行钠长石-白云母-刚玉-方解石域中。这种不常见的氧镁铁矿呈深棕色，相当于具有玻璃光泽的短棱柱状异质晶体，尺寸可达约 100 微米。尺寸为 4 × 3 厘米。氧镁镁石具有光学单轴性 (–)，ω = 1.6453(5) 和 ɛ = 1.6074(18)；其计算密度为3.069 g.cm –3，相容性指数为0.016。Beluga 氧化钠镁石具有三角对称性，空间群R 3 m ，a = 15.9121(2) Å，c = 7.1788(10) Å，V = 1574.12(5) Å 3，Z = 3。晶体结构精修为R 1 = 1.45，使用 1613 个独特的反射。经验晶体化学式为X (Na 0.88 Ca 0.08 □ 0.03 K 0.01 ) Y (Al 1.49 Mg 1.31 Fe 0.15 Ti 0.04 Zn 0.01 ) Z (Al 5.42 Mg 0.58 ) T (Si 5.84 Al 0.16 O 18 ) B (BO 3 ) 3V (OH 2.95 O 0.05 ) W ( O 0.84 OH 0.01 F 0.15 )。

自然界中的氧化镁镁石通常以与镁铁矿、氧化镁镁石和氧化氧化镁镁石的固溶体形式存在。在 Beluga 矿点，其少量的 Al、空位 [□] 和 Ca 最有可能通过 (□Al)(NaR 2+ ) –1和 (CaMg)(NaAl) –1氧镁交换来补偿。镁铁矿和镁镁铁矿成分。白鲸的氧化镁镁矿产状的特点是富镁环境，与原始沉积序列的变质叠印有关。这一序列的海洋白云质泥质泥灰岩受到富含 (B,Cl) 流体的影响，这些流体可能近端源自变质作用逆行阶段硅酸钙中的矿物分解反应。该地区是电气石+刚玉组合的罕见例子。