Hezuolinite, (Sr,REE)4Zr(Ti,Fe3+,Fe2+)2Ti2O8(Si2O7)2, a new mineral species of the chevkinite group from Saima alkaline complex, Liaoning Province, NE China
Hezuolinite, (Sr,REE)4Zr(Ti,Fe3+,Fe2+)2Ti2O8(Si2O7)2, a new mineral species of the chevkinite group from Saima alkaline complex, Liaoning Province, NE China
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DOI：
10.1127/0935-1221/2011/0023-2158
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发表时间：
2012-02-01
影响因子：
2.1
通讯作者：
Tillmanns, Ekkehart
中科院分区：
文献类型：
--
作者：
Yang, Zhuming;Giester, Gerald;Tillmanns, Ekkehart
禾座岭石是辽宁赛马碱性杂岩中的一种副矿物。该矿物以非变质颗粒形式出现在绿色霓霞正长岩中，与微斜长石、霞石、霓石、黑云母、真透辉石、菱闪石和钛铁矿共生。这些非对称晶体的大小为几百微米。矿物呈黑色，带深褐色条纹。它是半透明的，有光泽。未观察到解理或分离。它很脆，有贝壳状断裂。硬度为VHN 100 683-964 kg mm（-2）（莫氏硬度为5.5-6）。测得的密度为4.28 g cm（-3），根据经验化学式计算的值为4.30 g cm（-3）。在光学性质上，蛇绿岩为负双轴性，n > 1.8，2 V = 75 °。分散性强，r > v。矿物表现出强烈的多色性，从浅棕色到深棕色。25次分析的平均值得到经验式（Sr2.15Ce0.55 La-0.49 Ca0.49Na0.12Nd0.09 Pr0.03Th0.03Sm0.01 Eu-0.01）（Sigma 3.98）（Zr-0.82 Fe 2 + 0.14Hf0.02Mn0.01）（Sigma 1.00）（Ti-1.38 Fe 3+（0.36）Fe 2+（0.14）Al-0.04 Nb-0.02）（Sigma 1.94）Ti 2 O 8（Si2.01O7）（2），基于O = 22。简化公式为（Sr，REE）（4）Zr（Ti，Fe 3+，Fe 2+）（2）Ti 2 O 8（Si 2 O 7）（2），理想的是Sr 2 REE 2 Zr（Fe 2+）Ti 3 O 8（Si 2 O 7）（2）。2.98（100）（-204）、3.02（90）（-313）、1.96（90）（024）、2.18（40）（-422）和2.84（70）（020）。该结构在空间群C2/m中解析和精化，其中a = 13.973（3），B = 5.6984（11），c = 11.988（2）埃，β = 114.10（1）度，V = 871.3（3）埃（3）3，Z = 2，至R1 = 0.037，wR ~ 2 = 0.097。Sr-O、Zr-O和Ti（1）-O距离的变化证实了稀土元素对Sr、Fe对Ti的部分替代。在硅镁矾结构（P2（1）/a）中，O（1）、O（2）和O（3）位分别分裂为O（1）和O（1 '）、O（2）和O（2'）、O（3）和O（3 '）位。硅（1）-O（7）-Si（2）角在hezuolinite是175.8度，是明显小于弯曲比rengeite（169.7度）。观测到的系统轨道符合C2/m空间群。蛇左岭石是红柱石亚族的一员，可以被认为是介于红柱石和红柱石之间的化学中间体。
Hezuolinite is a new mineral species occurring as an accessory mineral in the Saima alkaline complex in Liaoning Province, NE China. The mineral occurs in a green-aegirine nepheline syenite as non-metamict grains and is associated with microcline, nepheline, aegirine, biotite, eudialyte, rinkite and titanite. The anhedral crystals are several hundred micrometres in size. The mineral is black with dark-brown streak. It is translucent with a resinous luster. Cleavage or parting was not observed. It is brittle with a conchoidal fracture. The hardness is VHN100 683-964 kg mm(-2) (5.5-6 on Mohs' scale). The measured density is 4.28 g cm(-3), and the calculated value is 4.30 g cm(-3) from the empirical chemical formula. Optically, hezuolinite is biaxial negative, with n > 1.8 and 2V = 75 degrees. The dispersion is strong with r > v. The mineral shows a strong pleochroism, from pale brown to dark brown. The average of twenty-five analyses leads to the empirical formula (Sr2.15Ce0.55 La-0.49 Ca0.49Na0.12Nd0.09 Pr0.03Th0.03Sm0.01 Eu-0.01)(Sigma 3.98) (Zr-0.82 Fe2+ 0.14Hf0.02Mn0.01)(Sigma 1.00) (Ti-1.38 Fe3+ (0.36) Fe2+ (0.14) Al-0.04 Nb-0.02)(Sigma 1.94)Ti2O8 (Si2.01O7)(2), on the basis of O = 22. The simplified formula is (Sr,REE)(4)Zr(Ti,Fe3+, Fe2+)(2)Ti2O8(Si2O7)(2), ideally Sr2REE2Zr(Fe2+)Ti3O8(Si2O7)(2).The five strongest reflections in the X-ray powder-diffraction pattern [d in angstrom (I)(hkl)] are: 2.98(100)(-204), 3.02(90)(-313), 1.96(90)(024), 2.18(40)(-422), and 2.84(70)(020). The structure was solved and refined in space group C2/m, with a = 13.973(3), b = 5.6984(11), c = 11.988(2) angstrom, beta = 114.10(1)degrees, V = 871.3(3) angstrom(3) 3, Z = 2, to R1 = 0.037, wR2 = 0.097.The structure of hezuolinite is similar to rengeite. The changes of Sr-O, Zr-O and Ti(1)-O distances confirm partial substitutions of REE for Sr, and Fe for Ti. The sites of O(1), O(2) and O(3) of the hezuolinite structure (C2/m) are split into O(1) and O(1'), O(2) and O(2'), O(3) and O(3') sites in the rengeite structure (P2(1)/a), respectively. The Si(1)-O(7)-Si(2) angle in hezuolinite is 175.8 degrees, and is significantly less bent than in rengeite (169.7 degrees). The observed systematic extinctions are in agreement with space group C2/m. Hezuolinite is a member of the perrierite-subgroup and can be considered as a chemical intermediate between rengeite and perrierite.